Split Ground/Power planes for sensitive analog, vs glitchy digital...

[Ricky]

On Monday, July 31, 2023 at 6:57:50 PM UTC-4, John Larkin wrote:

On Mon, 31 Jul 2023 15:10:02 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:
On Monday, July 31, 2023 at 3:14:46?PM UTC-4, Joerg wrote:
On 7/22/23 1:43 PM, Ricky wrote:
On Saturday, July 22, 2023 at 4:33:25?PM UTC-4, John Larkin wrote:
On Sat, 22 Jul 2023 13:17:35 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:

I took a class many years ago, where they talked about creating separate power and ground planes for the analog and digital circuitry on a board. ...


For the vast majority of situations that is a bad idea. Often tought by
acedemians who never really designed anything meaningful for industry,
inclusing some at our university.

\"Acedemians\" such as the chip designers? I guess their chips are not assembled onto boards for qualification.


Of course, the ground planes would be joined at one location, typically under the chip that had both analog and digital signals, like an ADC or DAC.
And like John said, of course that chip is the only one in the universe
that needs access to two or more of the grounds

The minute there is one more device like that the whole concept goes
kablouie.

That simply shows you don\'t understand the concept. Larkin says he uses the same idea. He simply rationalizes it as being different by saying he only cuts the area on \"three sides\" rather than talking about how they are connected.
Pot of maybe a thousand board designs, I think I have done that twice,
both times for boards with thermocouple inputs and high power drivers
nearby. Just diverting some ground-plane currents around a sheltered
niche.

You are ignoring that each chip which needs such a scheme can have its own analog ground area. Or, if the two chips can be placed side by side, they can share the connection between the common analog and digital ground planes. If neither is possible, then, no, this won\'t work. But then there are exactly zero techniques that work for every situation. In particular, the single, board wide ground area is not the best approach for some designs.


The high speed digital signals would be routed anywhere other than over the analog ground planes, of course. Some people are telling me this is a bad idea, as if I have totally separate ground planes.

Any comments?
Almost always best is one solid ground plane for everything, bolted to
the metal case through every available spacer and bracket and
connector shell. We standardize on layer 2 for the ground plane, and
occasioanlly also layer 5 (of 6) mostly to keep the copper balanced
when we don\'t need a bunch of power planes..

Handle any microvolt ground loops properly of course.

There\'s no reason for any two grounds to be at different potentials..

The IC people think *their* single chip is the center of the universe,
and that the two system grounds should only meet under their single
chip.

Hmmm... Why would two ground planes be at different potentials if they are connected? Perhaps you missed where I said, \"joined at one location\"..

Think of two grounds as a dipole. Yeah, they are connected somewhere in
the center but in RF terms that hardly means anything. Case in point:
All the yagi antennas I ever built have a driven element that is one
contiguous aluminum tube, no separation in the middle. Yet they radiate
and receive as calculated. When you look at the gamma match concept I
use to feed those it might become more clear where disaster can strike
in a split ground system:

https://www.electronics-notes.com/articles/antennas-propagation/antenna-theory/antenna-gamma-impedance-matching.php

Another (noisy) IC, transistor stage or whatever somewhere off center
connecting to one of the ground planes will make the whole contraption
radiate. That can cause you to fail radiated and sometimes even
conducted EMC. It also \"receives\", which may cause you to fail the
susceptibility test which is nowadays part of the EMC test protocol.

I don\'t know why you are trying to make antennas on the ground plane. There should be very, very little current flowing through the connection between the analog and digital ground areas, so very insignificant radiation.

As for susceptibility, how does the connection make the design more susceptible? Even an intact ground plane is susceptible to received radiation. It produces very little voltage because of the low resistance of the plane. Two connected planes can be connected with as low a resistance as desired, again, minimizing the induced voltage.


The idea is that some circuitry, such as a switching power converter or a power hungry IC, puts large currents in the ground plane, which do not limit themselves to the immediate area under that circuit.

Connecting the two ground planes at one spot, limits the impact of these currents to the digital plane.

In practice it usually doesn\'t. RF always tries to find another path
around it, and finds it.

You aren\'t making sense. What RF from what source? What other paths?


Of course, there is always more to a design than one such detail. This still requires the elimination of ground loops from other ground connections, such as off board.

Exactly, and in practice you often can\'t. Outside stuff has to connect
to your system. Mains power, protective earth, some sensors, maybe a
keyboard, a touch screen that by its very nature can be touched by a
conductive human finger, and so on.

I\'ve been on the beat for many decades. In all that time I never saw a
mixed-signal design with a split ground that worked reliably. Many times
I was called in as a consultant to \"make it work\", upon which I removed
all the ground splits. Often against vehement protests on the part of
client engineers. My own designs never had split grounds and they always
worked.

I can\'t speak to designs I know nothing of. When you talk about \"split planes\", you make it sound like they are not connected. My concept is exactly like the scheme that Larkin uses. We only differ by how much connection is made between them. Larkin is simply afraid to extend the scheme to its fullest, practical use.


There are very few exceptions. In sensitive audio setups an occasional
split can make sense but in my experience even there it\'s rare.

Ok, so then you agree with the concept. Thank you.


Then
there are safety rules. For example, in med-tech we must often maintain
full defibrillator-proof isolation when used in cardiac situations,
meaning it has to withstand 5kV. There the grounds aren\'t connected
anywhere.

And yet, you manage to not have excessive noise, yes?

You seem to actually be saying all methods work. Ok, I won\'t disagree. I simply find the use of borders around noisy, or sensitive circuits, is a good way to isolate noise. You seem to agree, but, like Larkin, get all wigged out by talking about this being a reasonable idea, even though you eventually admit that it works.

I think enough has been said about this. There\'s nothing new in your post. You are agreeing with Larkin, who also agrees with me. You both simply have trouble admitting that you agree.
Hilarious. I never join \"analog ground\" and \"digital ground\" under a
chip, much less many chips. In fact, I never have two grounds.

I don\'t have two grounds either. They are joined to form a single ground, just like you said you do.

--

Rick C.

-+- Get 1,000 miles of free Supercharging
-+- Tesla referral code - https://ts.la/richard11209

 

[Ricky]

On Monday, July 31, 2023 at 8:23:53 PM UTC-4, John Larkin wrote:

On Mon, 31 Jul 2023 17:09:43 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:



I think enough has been said about this. There\'s nothing new in your post. You are agreeing with Larkin, who also agrees with me. You both simply have trouble admitting that you agree.
Hilarious. I never join \"analog ground\" and \"digital ground\" under a
chip, much less many chips. In fact, I never have two grounds.

Neither do I. When they are joined, they are only one ground, exactly as you have said you have done.
The cut in the ground plane here

https://www.dropbox.com/scl/fi/0xbq2zh5rer3smookdak5/Chimera_Ground_Cut.jpg?rlkey=enbp8fd2l451jkxmv9jqz8blr&raw=1

keeps the thermocouple circuit from seeing microvolt potentials caused
by voltage drops in the ground plane. But the amp circuits are still
solidly grounded to the only ground.

Ok, this is exactly what I\'m talking about. You do isolate sensitive circuits by cuts in the ground plane. So, you are agreeing with me that this is a useful technique to isolate sensitive circuits, from noisy circuits.

So, if this corner of the board had a high speed analog signal coming in with a 500 MSPS ADC, and some noisy circuitry to the left, would the ground plane be continuous or cut into sections as you have done here? Where would the split be?


> Show us your board.

We\'ve had this discussion before. Many of my designs are for customers where I can\'t just exhibit their IP. I have one current design that is 0.85\" x 4.5\", with no high current pulses or edges anywhere near the analog, so doesn\'t need such isolation. I\'ve posted it before and you were not interested in discussing it. At less than 3.5 sq inches, it has more circuitry on it than probably 15 sq inches of your typical boards. I seldom have the luxury of being able to spread things out to facilitate layout. I have to shoehorn in a lot of circuitry and find ways to make the layout work. I also avoid BGAs as much as possible, but this time I can\'t avoid it.

--

Rick C.

-++ Get 1,000 miles of free Supercharging
-++ Tesla referral code - https://ts.la/richard11209

 

[John Larkin]

On Mon, 31 Jul 2023 19:26:17 -0700 (PDT), Ricky
<gnuarm.deletethisbit@gmail.com> wrote:

On Monday, July 31, 2023 at 8:23:53?PM UTC-4, John Larkin wrote:
On Mon, 31 Jul 2023 17:09:43 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:



I think enough has been said about this. There\'s nothing new in your post. You are agreeing with Larkin, who also agrees with me. You both simply have trouble admitting that you agree.
Hilarious. I never join \"analog ground\" and \"digital ground\" under a
chip, much less many chips. In fact, I never have two grounds.

Neither do I. When they are joined, they are only one ground, exactly as you have said you have done.
The cut in the ground plane here

https://www.dropbox.com/scl/fi/0xbq2zh5rer3smookdak5/Chimera_Ground_Cut.jpg?rlkey=enbp8fd2l451jkxmv9jqz8blr&raw=1

keeps the thermocouple circuit from seeing microvolt potentials caused
by voltage drops in the ground plane. But the amp circuits are still
solidly grounded to the only ground.

Ok, this is exactly what I\'m talking about. You do isolate sensitive circuits by cuts in the ground plane. So, you are agreeing with me that this is a useful technique to isolate sensitive circuits, from noisy circuits.

This isn\'t a noise issue; it\'s a matter of keeping a section of ground
equipotential at low frequencies.

But I thought the issue was having separate analog and digital grounds
that meet at one point under some delicate part. I can\'t agree on that
one.

So, if this corner of the board had a high speed analog signal coming in with a 500 MSPS ADC, and some noisy circuitry to the left, would the ground plane be continuous or cut into sections as you have done here? Where would the split be?

It\'s a thermocouple input. Nothing in that section is high speed.

Show us your board.

We\'ve had this discussion before. Many of my designs are for customers where I can\'t just exhibit their IP.

Oh.

 

[John Larkin]

On Mon, 31 Jul 2023 19:10:32 -0700 (PDT), Ricky
<gnuarm.deletethisbit@gmail.com> wrote:

On Monday, July 31, 2023 at 6:57:50?PM UTC-4, John Larkin wrote:
On Mon, 31 Jul 2023 15:10:02 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:
On Monday, July 31, 2023 at 3:14:46?PM UTC-4, Joerg wrote:
On 7/22/23 1:43 PM, Ricky wrote:
On Saturday, July 22, 2023 at 4:33:25?PM UTC-4, John Larkin wrote:
On Sat, 22 Jul 2023 13:17:35 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:

I took a class many years ago, where they talked about creating separate power and ground planes for the analog and digital circuitry on a board. ...


For the vast majority of situations that is a bad idea. Often tought by
acedemians who never really designed anything meaningful for industry,
inclusing some at our university.

\"Acedemians\" such as the chip designers? I guess their chips are not assembled onto boards for qualification.


Of course, the ground planes would be joined at one location, typically under the chip that had both analog and digital signals, like an ADC or DAC.
And like John said, of course that chip is the only one in the universe
that needs access to two or more of the grounds

The minute there is one more device like that the whole concept goes
kablouie.

That simply shows you don\'t understand the concept. Larkin says he uses the same idea. He simply rationalizes it as being different by saying he only cuts the area on \"three sides\" rather than talking about how they are connected.
Pot of maybe a thousand board designs, I think I have done that twice,
both times for boards with thermocouple inputs and high power drivers
nearby. Just diverting some ground-plane currents around a sheltered
niche.

You are ignoring that each chip which needs such a scheme can have its own analog ground area. Or, if the two chips can be placed side by side, they can share the connection between the common analog and digital ground planes. If neither is possible, then, no, this won\'t work. But then there are exactly zero techniques that work for every situation. In particular, the single, board wide ground area is not the best approach for some designs.


The high speed digital signals would be routed anywhere other than over the analog ground planes, of course. Some people are telling me this is a bad idea, as if I have totally separate ground planes.

Any comments?
Almost always best is one solid ground plane for everything, bolted to
the metal case through every available spacer and bracket and
connector shell. We standardize on layer 2 for the ground plane, and
occasioanlly also layer 5 (of 6) mostly to keep the copper balanced
when we don\'t need a bunch of power planes..

Handle any microvolt ground loops properly of course.

There\'s no reason for any two grounds to be at different potentials.

The IC people think *their* single chip is the center of the universe,
and that the two system grounds should only meet under their single
chip.

Hmmm... Why would two ground planes be at different potentials if they are connected? Perhaps you missed where I said, \"joined at one location\".

Think of two grounds as a dipole. Yeah, they are connected somewhere in
the center but in RF terms that hardly means anything. Case in point:
All the yagi antennas I ever built have a driven element that is one
contiguous aluminum tube, no separation in the middle. Yet they radiate
and receive as calculated. When you look at the gamma match concept I
use to feed those it might become more clear where disaster can strike
in a split ground system:

https://www.electronics-notes.com/articles/antennas-propagation/antenna-theory/antenna-gamma-impedance-matching.php

Another (noisy) IC, transistor stage or whatever somewhere off center
connecting to one of the ground planes will make the whole contraption
radiate. That can cause you to fail radiated and sometimes even
conducted EMC. It also \"receives\", which may cause you to fail the
susceptibility test which is nowadays part of the EMC test protocol.

I don\'t know why you are trying to make antennas on the ground plane. There should be very, very little current flowing through the connection between the analog and digital ground areas, so very insignificant radiation.

As for susceptibility, how does the connection make the design more susceptible? Even an intact ground plane is susceptible to received radiation. It produces very little voltage because of the low resistance of the plane. Two connected planes can be connected with as low a resistance as desired, again, minimizing the induced voltage.


The idea is that some circuitry, such as a switching power converter or a power hungry IC, puts large currents in the ground plane, which do not limit themselves to the immediate area under that circuit.

Connecting the two ground planes at one spot, limits the impact of these currents to the digital plane.

In practice it usually doesn\'t. RF always tries to find another path
around it, and finds it.

You aren\'t making sense. What RF from what source? What other paths?


Of course, there is always more to a design than one such detail. This still requires the elimination of ground loops from other ground connections, such as off board.

Exactly, and in practice you often can\'t. Outside stuff has to connect
to your system. Mains power, protective earth, some sensors, maybe a
keyboard, a touch screen that by its very nature can be touched by a
conductive human finger, and so on.

I\'ve been on the beat for many decades. In all that time I never saw a
mixed-signal design with a split ground that worked reliably. Many times
I was called in as a consultant to \"make it work\", upon which I removed
all the ground splits. Often against vehement protests on the part of
client engineers. My own designs never had split grounds and they always
worked.

I can\'t speak to designs I know nothing of. When you talk about \"split planes\", you make it sound like they are not connected. My concept is exactly like the scheme that Larkin uses. We only differ by how much connection is made between them. Larkin is simply afraid to extend the scheme to its fullest, practical use.


There are very few exceptions. In sensitive audio setups an occasional
split can make sense but in my experience even there it\'s rare.

Ok, so then you agree with the concept. Thank you.


Then
there are safety rules. For example, in med-tech we must often maintain
full defibrillator-proof isolation when used in cardiac situations,
meaning it has to withstand 5kV. There the grounds aren\'t connected
anywhere.

And yet, you manage to not have excessive noise, yes?

You seem to actually be saying all methods work. Ok, I won\'t disagree. I simply find the use of borders around noisy, or sensitive circuits, is a good way to isolate noise. You seem to agree, but, like Larkin, get all wigged out by talking about this being a reasonable idea, even though you eventually admit that it works.

I think enough has been said about this. There\'s nothing new in your post. You are agreeing with Larkin, who also agrees with me. You both simply have trouble admitting that you agree.
Hilarious. I never join \"analog ground\" and \"digital ground\" under a
chip, much less many chips. In fact, I never have two grounds.

I don\'t have two grounds either. They are joined to form a single ground, just like you said you do.

\"They are joined?\" What does that mean? Is a single ground \"joined\" to
itself?

Sounds like new-speak gendering, where one person is \"they.\"

 

[Ricky]

On Tuesday, August 1, 2023 at 12:26:09 AM UTC-4, John Larkin wrote:

On Mon, 31 Jul 2023 19:26:17 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:
On Monday, July 31, 2023 at 8:23:53?PM UTC-4, John Larkin wrote:
On Mon, 31 Jul 2023 17:09:43 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:



I think enough has been said about this. There\'s nothing new in your post. You are agreeing with Larkin, who also agrees with me. You both simply have trouble admitting that you agree.
Hilarious. I never join \"analog ground\" and \"digital ground\" under a
chip, much less many chips. In fact, I never have two grounds.

Neither do I. When they are joined, they are only one ground, exactly as you have said you have done.
The cut in the ground plane here

https://www.dropbox.com/scl/fi/0xbq2zh5rer3smookdak5/Chimera_Ground_Cut.jpg?rlkey=enbp8fd2l451jkxmv9jqz8blr&raw=1

keeps the thermocouple circuit from seeing microvolt potentials caused
by voltage drops in the ground plane. But the amp circuits are still
solidly grounded to the only ground.

Ok, this is exactly what I\'m talking about. You do isolate sensitive circuits by cuts in the ground plane. So, you are agreeing with me that this is a useful technique to isolate sensitive circuits, from noisy circuits.
This isn\'t a noise issue; it\'s a matter of keeping a section of ground
equipotential at low frequencies.

Hmmm... so if they are not \"equipotential\" at low frequencies, that\'s not a noise issue??? Sure sounds like a noise issue to me! If you preserve the \"equipotential\" aspect of the analog section of the ground plane by making cuts in the plane, how is that different from what I propose??? What exactly, are the cuts in your ground plane separating? How do you choose where to put them?

But I thought the issue was having separate analog and digital grounds
that meet at one point under some delicate part. I can\'t agree on that
one.

It\'s not that the part is \"delicate\". You will find nothing to show I said that. The parts would be devices like ADCs, which have both high speed digital (often arranged on one side of the chip package to allow this sort of ground plane design) as well as a sensitive analog section.

So, if this corner of the board had a high speed analog signal coming in with a 500 MSPS ADC, and some noisy circuitry to the left, would the ground plane be continuous or cut into sections as you have done here? Where would the split be?
It\'s a thermocouple input. Nothing in that section is high speed.

Of course. That\'s the circuitry that is completely within the analog section of the ground plane, separated from the rest by the cuts.


But that\'s not the question I asked. Again... \"if this corner of the board had a high speed analog signal coming in with a 500 MSPS ADC, and some noisy circuitry to the left, would the ground plane be continuous or cut into sections as you have done here? Where would the split be?\"

Please try to answer this question as simply and directly as possible, rather than dodging the question.

Show us your board.

We\'ve had this discussion before. Many of my designs are for customers where I can\'t just exhibit their IP.
Oh.

Your work is different. Mostly you design products that you sell. Many people here can\'t show their designs. I recall one guy who was designing toys and could not even tell us what he was designing.

This should be of no surprise to you.

--

Rick C.

+-- Get 1,000 miles of free Supercharging
+-- Tesla referral code - https://ts.la/richard11209

 

[Ricky]

On Tuesday, August 1, 2023 at 12:29:59 AM UTC-4, John Larkin wrote:

On Mon, 31 Jul 2023 19:10:32 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:
On Monday, July 31, 2023 at 6:57:50?PM UTC-4, John Larkin wrote:
On Mon, 31 Jul 2023 15:10:02 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:
On Monday, July 31, 2023 at 3:14:46?PM UTC-4, Joerg wrote:
On 7/22/23 1:43 PM, Ricky wrote:
On Saturday, July 22, 2023 at 4:33:25?PM UTC-4, John Larkin wrote:
On Sat, 22 Jul 2023 13:17:35 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:

I took a class many years ago, where they talked about creating separate power and ground planes for the analog and digital circuitry on a board. ...


For the vast majority of situations that is a bad idea. Often tought by
acedemians who never really designed anything meaningful for industry,
inclusing some at our university.

\"Acedemians\" such as the chip designers? I guess their chips are not assembled onto boards for qualification.


Of course, the ground planes would be joined at one location, typically under the chip that had both analog and digital signals, like an ADC or DAC.
And like John said, of course that chip is the only one in the universe
that needs access to two or more of the grounds

The minute there is one more device like that the whole concept goes
kablouie.

That simply shows you don\'t understand the concept. Larkin says he uses the same idea. He simply rationalizes it as being different by saying he only cuts the area on \"three sides\" rather than talking about how they are connected.
Pot of maybe a thousand board designs, I think I have done that twice,
both times for boards with thermocouple inputs and high power drivers
nearby. Just diverting some ground-plane currents around a sheltered
niche.

You are ignoring that each chip which needs such a scheme can have its own analog ground area. Or, if the two chips can be placed side by side, they can share the connection between the common analog and digital ground planes. If neither is possible, then, no, this won\'t work. But then there are exactly zero techniques that work for every situation. In particular, the single, board wide ground area is not the best approach for some designs.


The high speed digital signals would be routed anywhere other than over the analog ground planes, of course. Some people are telling me this is a bad idea, as if I have totally separate ground planes.

Any comments?
Almost always best is one solid ground plane for everything, bolted to
the metal case through every available spacer and bracket and
connector shell. We standardize on layer 2 for the ground plane, and
occasioanlly also layer 5 (of 6) mostly to keep the copper balanced
when we don\'t need a bunch of power planes..

Handle any microvolt ground loops properly of course.

There\'s no reason for any two grounds to be at different potentials.

The IC people think *their* single chip is the center of the universe,
and that the two system grounds should only meet under their single
chip.

Hmmm... Why would two ground planes be at different potentials if they are connected? Perhaps you missed where I said, \"joined at one location\".

Think of two grounds as a dipole. Yeah, they are connected somewhere in
the center but in RF terms that hardly means anything. Case in point:
All the yagi antennas I ever built have a driven element that is one
contiguous aluminum tube, no separation in the middle. Yet they radiate
and receive as calculated. When you look at the gamma match concept I
use to feed those it might become more clear where disaster can strike
in a split ground system:

https://www.electronics-notes.com/articles/antennas-propagation/antenna-theory/antenna-gamma-impedance-matching.php

Another (noisy) IC, transistor stage or whatever somewhere off center
connecting to one of the ground planes will make the whole contraption
radiate. That can cause you to fail radiated and sometimes even
conducted EMC. It also \"receives\", which may cause you to fail the
susceptibility test which is nowadays part of the EMC test protocol..

I don\'t know why you are trying to make antennas on the ground plane. There should be very, very little current flowing through the connection between the analog and digital ground areas, so very insignificant radiation..

As for susceptibility, how does the connection make the design more susceptible? Even an intact ground plane is susceptible to received radiation. It produces very little voltage because of the low resistance of the plane. Two connected planes can be connected with as low a resistance as desired, again, minimizing the induced voltage.


The idea is that some circuitry, such as a switching power converter or a power hungry IC, puts large currents in the ground plane, which do not limit themselves to the immediate area under that circuit.

Connecting the two ground planes at one spot, limits the impact of these currents to the digital plane.

In practice it usually doesn\'t. RF always tries to find another path
around it, and finds it.

You aren\'t making sense. What RF from what source? What other paths?


Of course, there is always more to a design than one such detail. This still requires the elimination of ground loops from other ground connections, such as off board.

Exactly, and in practice you often can\'t. Outside stuff has to connect
to your system. Mains power, protective earth, some sensors, maybe a
keyboard, a touch screen that by its very nature can be touched by a
conductive human finger, and so on.

I\'ve been on the beat for many decades. In all that time I never saw a
mixed-signal design with a split ground that worked reliably. Many times
I was called in as a consultant to \"make it work\", upon which I removed
all the ground splits. Often against vehement protests on the part of
client engineers. My own designs never had split grounds and they always
worked.

I can\'t speak to designs I know nothing of. When you talk about \"split planes\", you make it sound like they are not connected. My concept is exactly like the scheme that Larkin uses. We only differ by how much connection is made between them. Larkin is simply afraid to extend the scheme to its fullest, practical use.


There are very few exceptions. In sensitive audio setups an occasional
split can make sense but in my experience even there it\'s rare.

Ok, so then you agree with the concept. Thank you.


Then
there are safety rules. For example, in med-tech we must often maintain
full defibrillator-proof isolation when used in cardiac situations,
meaning it has to withstand 5kV. There the grounds aren\'t connected
anywhere.

And yet, you manage to not have excessive noise, yes?

You seem to actually be saying all methods work. Ok, I won\'t disagree.. I simply find the use of borders around noisy, or sensitive circuits, is a good way to isolate noise. You seem to agree, but, like Larkin, get all wigged out by talking about this being a reasonable idea, even though you eventually admit that it works.

I think enough has been said about this. There\'s nothing new in your post. You are agreeing with Larkin, who also agrees with me. You both simply have trouble admitting that you agree.
Hilarious. I never join \"analog ground\" and \"digital ground\" under a
chip, much less many chips. In fact, I never have two grounds.

I don\'t have two grounds either. They are joined to form a single ground, just like you said you do.
\"They are joined?\" What does that mean? Is a single ground \"joined\" to
itself?

Sounds like new-speak gendering, where one person is \"they.\"

I suppose it should not surprise me that you resort to being snarky about this. You know exactly what I mean. All along, I have talked about two *areas* of the ground plane, joined at an optimal point, so that it is a single ground plane electrically.

Now, that it is very clear you acknowledge using the same technique, you are trying to hide by not discussing the facts, and playing your usual games.

This is about the point where you will become offended, saying I am being snarky, and refuse to discuss the actual topic further, or to answer my questions in a meaningful way. That\'s ok. I\'m not expecting anything different.

--

Rick C.

+-+ Get 1,000 miles of free Supercharging
+-+ Tesla referral code - https://ts.la/richard11209

 

[Jan Panteltje]

On a sunny day (Mon, 31 Jul 2023 12:21:52 -0700 (PDT)) it happened John
Walliker <jrwalliker@gmail.com> wrote in
<7c7c23fc-5e58-4a3e-9af1-af05bd3fbf4dn@googlegroups.com>:

On Monday, 31 July 2023 at 20:14:46 UTC+1, Joerg wrote:
On 7/22/23 1:43 PM, Ricky wrote:
On Saturday, July 22, 2023 at 4:33:25 PM UTC-4, John Larkin wro=
te:
On Sat, 22 Jul 2023 13:17:35 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:

I took a class many years ago, where they talked about creating separ=
ate power and ground planes for the analog and digital circuitry on a board=
. ...


For the vast majority of situations that is a bad idea. Often tought by=

acedemians who never really designed anything meaningful for industry,
inclusing some at our university.
Of course, the ground planes would be joined at one location, typical=
ly under the chip that had both analog and digital signals, like an ADC or =
DAC.
And like John said, of course that chip is the only one in the universe=

that needs access to two or more of the grounds

The minute there is one more device like that the whole concept goes
kablouie.

The high speed digital signals would be routed anywhere other than ov=
er the analog ground planes, of course. Some people are telling me this is =
a bad idea, as if I have totally separate ground planes.

Any comments?
Almost always best is one solid ground plane for everything, bolted to=

the metal case through every available spacer and bracket and
connector shell. We standardize on layer 2 for the ground plane, and
occasioanlly also layer 5 (of 6) mostly to keep the copper balanced
when we don\'t need a bunch of power planes..

Handle any microvolt ground loops properly of course.

There\'s no reason for any two grounds to be at different potentials.=


The IC people think *their* single chip is the center of the universe,=

and that the two system grounds should only meet under their single
chip.

Hmmm... Why would two ground planes be at different potentials if they =
are connected? Perhaps you missed where I said, \"joined at one location\".=


Think of two grounds as a dipole. Yeah, they are connected somewhere in=

the center but in RF terms that hardly means anything. Case in point:
All the yagi antennas I ever built have a driven element that is one
contiguous aluminum tube, no separation in the middle. Yet they radiate=

and receive as calculated. When you look at the gamma match concept I
use to feed those it might become more clear where disaster can strike
in a split ground system:

https://www.electronics-notes.com/articles/antennas-propagation/antenna-t=
heory/antenna-gamma-impedance-matching.php

Another (noisy) IC, transistor stage or whatever somewhere off center
connecting to one of the ground planes will make the whole contraption
radiate. That can cause you to fail radiated and sometimes even
conducted EMC. It also \"receives\", which may cause you to fail the
susceptibility test which is nowadays part of the EMC test protocol.
The idea is that some circuitry, such as a switching power converter or=
a power hungry IC, puts large currents in the ground plane, which do not l=
imit themselves to the immediate area under that circuit.

Connecting the two ground planes at one spot, limits the impact of thes=
e currents to the digital plane.

In practice it usually doesn\'t. RF always tries to find another path
around it, and finds it.
Of course, there is always more to a design than one such detail. This =
still requires the elimination of ground loops from other ground connection=
s, such as off board.

Exactly, and in practice you often can\'t. Outside stuff has to connect
to your system. Mains power, protective earth, some sensors, maybe a
keyboard, a touch screen that by its very nature can be touched by a
conductive human finger, and so on.

I\'ve been on the beat for many decades. In all that time I never saw a
mixed-signal design with a split ground that worked reliably. Many times=

I was called in as a consultant to \"make it work\", upon which I removed=

all the ground splits. Often against vehement protests on the part of
client engineers. My own designs never had split grounds and they always=

worked.

+1 John

Yea, same here.
But be carefull, if you have a power supply section and some low signal RF stuff on the same PCB
make sure you do not introduce the power riplle in the RF parts, ground traces follow
from high power to low signal area, all very logical.
But can be done wrong if you insist.

I do remember one day I had an exam for some licence and had to do a PCB layout of some RF stage circuit diagram.
Was it ELectronic Technician NERG? Did it aside from other exams I had to do for the school, passed.

 

[Jan Panteltje]

On a sunny day (Mon, 31 Jul 2023 17:23:36 -0700) it happened John Larkin
<jlarkin@highlandSNIPMEtechnology.com> wrote in
<pqjgcilkioqd0e5gi5ls09iaid6u06jbve@4ax.com>:

On Mon, 31 Jul 2023 17:09:43 -0700 (PDT), Ricky
gnuarm.deletethisbit@gmail.com> wrote:



I think enough has been said about this. There\'s nothing new in your post. You are agreeing with Larkin, who also agrees
with me. You both simply have trouble admitting that you agree.
Hilarious. I never join \"analog ground\" and \"digital ground\" under a
chip, much less many chips. In fact, I never have two grounds.

Neither do I. When they are joined, they are only one ground, exactly as you have said you have done.

The cut in the ground plane here

https://www.dropbox.com/scl/fi/0xbq2zh5rer3smookdak5/Chimera_Ground_Cut.jpg?rlkey=enbp8fd2l451jkxmv9jqz8blr&raw=1

A circular ground loop picks up microwave or magnetic radiation ;-)

keeps the thermocouple circuit from seeing microvolt potentials caused
by voltage drops in the ground plane. But the amp circuits are still
solidly grounded to the only ground.

>Show us your board.

This is giggle-Hertz out and fast I/O via flat cable from a Rapsberry Pi in
http://panteltje.nl/pub/test_board_wiring_side_IMG_3921.GIF
there is a 1.something GHz VCO, an RF attenuater, a RF mixer and a lot of SMDs bottom right.
http://panteltje.nl/pub/test_board_component_side_1_IMG_3911.GIF

what\'s slower just uses wires...
No need for peeseebees

This is the real thing:
http://panteltje.nl/pub/board.gif

pussies

 

[Joe Gwinn]

On Mon, 31 Jul 2023 17:23:36 -0700, John Larkin
<jlarkin@highlandSNIPMEtechnology.com> wrote:

On Mon, 31 Jul 2023 17:09:43 -0700 (PDT), Ricky
gnuarm.deletethisbit@gmail.com> wrote:



I think enough has been said about this. There\'s nothing new in your post. You are agreeing with Larkin, who also agrees with me. You both simply have trouble admitting that you agree.
Hilarious. I never join \"analog ground\" and \"digital ground\" under a
chip, much less many chips. In fact, I never have two grounds.

Neither do I. When they are joined, they are only one ground, exactly as you have said you have done.

The cut in the ground plane here

https://www.dropbox.com/scl/fi/0xbq2zh5rer3smookdak5/Chimera_Ground_Cut.jpg?rlkey=enbp8fd2l451jkxmv9jqz8blr&raw=1

keeps the thermocouple circuit from seeing microvolt potentials caused
by voltage drops in the ground plane. But the amp circuits are still
solidly grounded to the only ground.

In fact, this is an implementation of the classic star-ground
approach, where the connection between ground areas is a bit of copper
foil an inch or two wide.

Joe Gwinn

 

[Joerg]

On 7/31/23 3:10 PM, Ricky wrote:

On Monday, July 31, 2023 at 3:14:46 PM UTC-4, Joerg wrote:
On 7/22/23 1:43 PM, Ricky wrote:
On Saturday, July 22, 2023 at 4:33:25 PM UTC-4, John Larkin
wrote:
On Sat, 22 Jul 2023 13:17:35 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:

I took a class many years ago, where they talked about
creating separate power and ground planes for the analog and
digital circuitry on a board. ...


For the vast majority of situations that is a bad idea. Often
tought by acedemians who never really designed anything meaningful
for industry, inclusing some at our university.

\"Acedemians\" such as the chip designers? I guess their chips are not
assembled onto boards for qualification.

Yeah, to some eval board and that\'s often it. With academians I meant
people tasked with teaching, research and publications. As found at
universities or ivory tower labs of large corporations. They often have
no or very little exposure to real \"electrical life\".

Of course, the ground planes would be joined at one location,
typically under the chip that had both analog and digital
signals, like an ADC or DAC.
And like John said, of course that chip is the only one in the
universe that needs access to two or more of the grounds

The minute there is one more device like that the whole concept
goes kablouie.

That simply shows you don\'t understand the concept. Larkin says he
uses the same idea. He simply rationalizes it as being different by
saying he only cuts the area on \"three sides\" rather than talking
about how they are connected.

You are ignoring that each chip which needs such a scheme can have
its own analog ground area. Or, if the two chips can be placed side
by side, they can share the connection between the common analog and
digital ground planes. If neither is possible, then, no, this won\'t
work. But then there are exactly zero techniques that work for every
situation. In particular, the single, board wide ground area is not
the best approach for some designs.

It is almost generally not possible in real life. It somehow seems you
don\'t want to believe me. Then just go ahead and split the grounds, it\'s
not my board.

The high speed digital signals would be routed anywhere other
than over the analog ground planes, of course. Some people
are telling me this is a bad idea, as if I have totally
separate ground planes.

Any comments?
Almost always best is one solid ground plane for everything,
bolted to the metal case through every available spacer and
bracket and connector shell. We standardize on layer 2 for the
ground plane, and occasioanlly also layer 5 (of 6) mostly to
keep the copper balanced when we don\'t need a bunch of power
planes..

Handle any microvolt ground loops properly of course.

There\'s no reason for any two grounds to be at different
potentials.

The IC people think *their* single chip is the center of the
universe, and that the two system grounds should only meet
under their single chip.

Hmmm... Why would two ground planes be at different potentials if
they are connected? Perhaps you missed where I said, \"joined at
one location\".

Think of two grounds as a dipole. Yeah, they are connected
somewhere in the center but in RF terms that hardly means anything.
Case in point: All the yagi antennas I ever built have a driven
element that is one contiguous aluminum tube, no separation in the
middle. Yet they radiate and receive as calculated. When you look
at the gamma match concept I use to feed those it might become more
clear where disaster can strike in a split ground system:

https://www.electronics-notes.com/articles/antennas-propagation/antenna-theory/antenna-gamma-impedance-matching.php



Another (noisy) IC, transistor stage or whatever somewhere off center
connecting to one of the ground planes will make the whole
contraption radiate. That can cause you to fail radiated and
sometimes even conducted EMC. It also \"receives\", which may cause
you to fail the susceptibility test which is nowadays part of the
EMC test protocol.

I don\'t know why you are trying to make antennas on the ground plane.
There should be very, very little current flowing through the
connection between the analog and digital ground areas, so very
insignificant radiation.

As for susceptibility, how does the connection make the design more
susceptible?

It allows more current to flow, making it a more efficient (unwanted)
antenna that receives stuff.

Even an intact ground plane is susceptible to received radiation. It
produces very little voltage because of the low resistance of the plane.
Two connected planes can be connected with as low a resistance as
desired, again, minimizing the induced voltage.

Resistance has almost nothing to do with this. It\'s the impedance that
counts and, most of all, where stuff couples in.

The idea is that some circuitry, such as a switching power
converter or a power hungry IC, puts large currents in the ground
plane, which do not limit themselves to the immediate area under
that circuit.

Connecting the two ground planes at one spot, limits the impact
of these currents to the digital plane.

In practice it usually doesn\'t. RF always tries to find another
path around it, and finds it.

You aren\'t making sense. What RF from what source? What other
paths?

RF from, for example, large motors starting up, nearby lightning,
welding equipment, a big AC unit being hard-switched on, et cetera.

Other paths is via externally connected sensors, power sources,
monitors, user interfaces and so on. I had explained that.

If you had read the explanation of the gamma match I brought up you\'d
understand. But maybe you don\'t want any advice, then so be it. I\'ve
seen plenty of folks who didn\'t believe it. Their designs failed and
mostly during EMC testing.

Of course, there is always more to a design than one such detail.
This still requires the elimination of ground loops from other
ground connections, such as off board.

Exactly, and in practice you often can\'t. Outside stuff has to
connect to your system. Mains power, protective earth, some
sensors, maybe a keyboard, a touch screen that by its very nature
can be touched by a conductive human finger, and so on.

I\'ve been on the beat for many decades. In all that time I never
saw a mixed-signal design with a split ground that worked reliably.
Many times I was called in as a consultant to \"make it work\", upon
which I removed all the ground splits. Often against vehement
protests on the part of client engineers. My own designs never had
split grounds and they always worked.

I can\'t speak to designs I know nothing of. When you talk about
\"split planes\", you make it sound like they are not connected.

They are nearly always connected somewhere because they have to. And
that\'s when the problems arise.

... My
concept is exactly like the scheme that Larkin uses. We only differ
by how much connection is made between them. Larkin is simply afraid
to extend the scheme to its fullest, practical use.

He is not afraid, he uses full ground planes just like I do. Because
that makes sense.

There are very few exceptions. In sensitive audio setups an
occasional split can make sense but in my experience even there
it\'s rare.

Ok, so then you agree with the concept. Thank you.

We don\'t. If you don\'t have an audio application I\'d never even consider
a split. Because in audio when you do it that causes a lot of other
grief such as susceptibility.

Then there are safety rules. For example, in med-tech we must often
maintain full defibrillator-proof isolation when used in cardiac
situations, meaning it has to withstand 5kV. There the grounds
aren\'t connected anywhere.

And yet, you manage to not have excessive noise, yes?

I do but that\'s because the grounds are _not_ connected. Even the power
is supplied in an isolated fashion, no connection.

You seem to actually be saying all methods work. Ok, I won\'t
disagree. I simply find the use of borders around noisy, or
sensitive circuits, is a good way to isolate noise. You seem to
agree, ...

I do not agree. Cutting voids into ground planes generally reduces the
nosie immunity of circuits and, therefore, I do not do it.

but, like Larkin, get all wigged out by talking about this
being a reasonable idea, even though you eventually admit that it
works.

I think enough has been said about this. There\'s nothing new in your
post. You are agreeing with Larkin, who also agrees with me. You
both simply have trouble admitting that you agree.

Nonsense. But go ahead, split the grounds, it\'s your design.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Ricky]

On Wednesday, August 2, 2023 at 3:30:00 PM UTC-4, Joerg wrote:

On 7/31/23 3:10 PM, Ricky wrote:
On Monday, July 31, 2023 at 3:14:46 PM UTC-4, Joerg wrote:
On 7/22/23 1:43 PM, Ricky wrote:
On Saturday, July 22, 2023 at 4:33:25 PM UTC-4, John Larkin
wrote:
On Sat, 22 Jul 2023 13:17:35 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:

I took a class many years ago, where they talked about
creating separate power and ground planes for the analog and
digital circuitry on a board. ...


For the vast majority of situations that is a bad idea. Often
tought by acedemians who never really designed anything meaningful
for industry, inclusing some at our university.

\"Acedemians\" such as the chip designers? I guess their chips are not
assembled onto boards for qualification.

Yeah, to some eval board and that\'s often it. With academians I meant
people tasked with teaching, research and publications. As found at
universities or ivory tower labs of large corporations. They often have
no or very little exposure to real \"electrical life\".

If you read the thread carefully, you will see the class I took was taught by Lee Ritchey, about as far from an academician as you can get. I don\'t know why you are talking about them.

Of course, the ground planes would be joined at one location,
typically under the chip that had both analog and digital
signals, like an ADC or DAC.
And like John said, of course that chip is the only one in the
universe that needs access to two or more of the grounds

The minute there is one more device like that the whole concept
goes kablouie.

That simply shows you don\'t understand the concept. Larkin says he
uses the same idea. He simply rationalizes it as being different by
saying he only cuts the area on \"three sides\" rather than talking
about how they are connected.

You are ignoring that each chip which needs such a scheme can have
its own analog ground area. Or, if the two chips can be placed side
by side, they can share the connection between the common analog and
digital ground planes. If neither is possible, then, no, this won\'t
work. But then there are exactly zero techniques that work for every
situation. In particular, the single, board wide ground area is not
the best approach for some designs.
It is almost generally not possible in real life. It somehow seems you
don\'t want to believe me. Then just go ahead and split the grounds, it\'s
not my board.

Your use of \"It\" is misplaced and unclear. But thank you for the permission to continue to design my own boards. That\'s very generous of you.

The high speed digital signals would be routed anywhere other
than over the analog ground planes, of course. Some people
are telling me this is a bad idea, as if I have totally
separate ground planes.

Any comments?
Almost always best is one solid ground plane for everything,
bolted to the metal case through every available spacer and
bracket and connector shell. We standardize on layer 2 for the
ground plane, and occasioanlly also layer 5 (of 6) mostly to
keep the copper balanced when we don\'t need a bunch of power
planes..

Handle any microvolt ground loops properly of course.

There\'s no reason for any two grounds to be at different
potentials.

The IC people think *their* single chip is the center of the
universe, and that the two system grounds should only meet
under their single chip.

Hmmm... Why would two ground planes be at different potentials if
they are connected? Perhaps you missed where I said, \"joined at
one location\".

Think of two grounds as a dipole. Yeah, they are connected
somewhere in the center but in RF terms that hardly means anything.
Case in point: All the yagi antennas I ever built have a driven
element that is one contiguous aluminum tube, no separation in the
middle. Yet they radiate and receive as calculated. When you look
at the gamma match concept I use to feed those it might become more
clear where disaster can strike in a split ground system:

https://www.electronics-notes.com/articles/antennas-propagation/antenna-theory/antenna-gamma-impedance-matching.php



Another (noisy) IC, transistor stage or whatever somewhere off center
connecting to one of the ground planes will make the whole
contraption radiate. That can cause you to fail radiated and
sometimes even conducted EMC. It also \"receives\", which may cause
you to fail the susceptibility test which is nowadays part of the
EMC test protocol.

I don\'t know why you are trying to make antennas on the ground plane.
There should be very, very little current flowing through the
connection between the analog and digital ground areas, so very
insignificant radiation.

As for susceptibility, how does the connection make the design more
susceptible?
It allows more current to flow, making it a more efficient (unwanted)
antenna that receives stuff.
Even an intact ground plane is susceptible to received radiation. It
produces very little voltage because of the low resistance of the plane.
Two connected planes can be connected with as low a resistance as
desired, again, minimizing the induced voltage.

Resistance has almost nothing to do with this. It\'s the impedance that
counts and, most of all, where stuff couples in.

Ok

The idea is that some circuitry, such as a switching power
converter or a power hungry IC, puts large currents in the ground
plane, which do not limit themselves to the immediate area under
that circuit.

Connecting the two ground planes at one spot, limits the impact
of these currents to the digital plane.

In practice it usually doesn\'t. RF always tries to find another
path around it, and finds it.

You aren\'t making sense. What RF from what source? What other
paths?

RF from, for example, large motors starting up, nearby lightning,
welding equipment, a big AC unit being hard-switched on, et cetera.

Again, ok. So, you are claiming that Larkin\'s use of cuts in the ground plane will cause it to pickup voltages from lightning and motor starts?

Other paths is via externally connected sensors, power sources,
monitors, user interfaces and so on. I had explained that.

Connection of external grounds is a whole \'nother problem. It is easy to create ground loops that will mess up any design.

If you had read the explanation of the gamma match I brought up you\'d
understand. But maybe you don\'t want any advice, then so be it. I\'ve
seen plenty of folks who didn\'t believe it. Their designs failed and
mostly during EMC testing.

My designs have always passed EMI testing, first time!

Of course, there is always more to a design than one such detail.
This still requires the elimination of ground loops from other
ground connections, such as off board.

Exactly, and in practice you often can\'t. Outside stuff has to
connect to your system. Mains power, protective earth, some
sensors, maybe a keyboard, a touch screen that by its very nature
can be touched by a conductive human finger, and so on.

I\'ve been on the beat for many decades. In all that time I never
saw a mixed-signal design with a split ground that worked reliably.
Many times I was called in as a consultant to \"make it work\", upon
which I removed all the ground splits. Often against vehement
protests on the part of client engineers. My own designs never had
split grounds and they always worked.

I can\'t speak to designs I know nothing of. When you talk about
\"split planes\", you make it sound like they are not connected.
They are nearly always connected somewhere because they have to. And
that\'s when the problems arise.

Which is why it\'s better to talk not about \"split planes\", but planes with cuts. I\'m sorry I used the term \"split planes\". This obviously confuses you greatly.

... My
concept is exactly like the scheme that Larkin uses. We only differ
by how much connection is made between them. Larkin is simply afraid
to extend the scheme to its fullest, practical use.

He is not afraid, he uses full ground planes just like I do. Because
that makes sense.

If you believe that, you didn\'t read his posts. He posted a link to an example where he added cuts to his ground plane to create a low noise region, one to isolate the ground currents so the low noise region was not disturbed. Maybe this link will work. If not, you will need to dig for his post.

https://www.google.com/url?hl=en&q=https://www.dropbox.com/scl/fi/0xbq2zh5rer3smookdak5/Chimera_Ground_Cut.jpg?rlkey%3Denbp8fd2l451jkxmv9jqz8blr%26raw%3D1&source=gmail&ust=1690942233249000&usg=AOvVaw1ECzm002Td0u3S4Y_5zY4L

Does this design not have two ground areas?

There are very few exceptions. In sensitive audio setups an
occasional split can make sense but in my experience even there
it\'s rare.

Ok, so then you agree with the concept. Thank you.

We don\'t. If you don\'t have an audio application I\'d never even consider
a split. Because in audio when you do it that causes a lot of other
grief such as susceptibility.

And yet, it works. You have acknowledged that you cut ground planes and Larkin has provided an image of one of his designs with a very significant cut in the ground plane, creating two ground areas. Why are you now denying this?

Then there are safety rules. For example, in med-tech we must often
maintain full defibrillator-proof isolation when used in cardiac
situations, meaning it has to withstand 5kV. There the grounds
aren\'t connected anywhere.

And yet, you manage to not have excessive noise, yes?

I do but that\'s because the grounds are _not_ connected. Even the power
is supplied in an isolated fashion, no connection.

Ok, so with no ground connection, this is not relevant to this discussion.

You seem to actually be saying all methods work. Ok, I won\'t
disagree. I simply find the use of borders around noisy, or
sensitive circuits, is a good way to isolate noise. You seem to
agree, ...


I do not agree. Cutting voids into ground planes generally reduces the
nosie immunity of circuits and, therefore, I do not do it.

And yet, you said you did. I\'m not sure what you mean by \"voids\" though. What is this \"void\" you are talking about? Maybe that\'s the problem. We are talking about two different things.

but, like Larkin, get all wigged out by talking about this
being a reasonable idea, even though you eventually admit that it
works.

I think enough has been said about this. There\'s nothing new in your
post. You are agreeing with Larkin, who also agrees with me. You
both simply have trouble admitting that you agree.

Nonsense. But go ahead, split the grounds, it\'s your design.

You are very gracious. Thank you.

--

Rick C.

++- Get 1,000 miles of free Supercharging
++- Tesla referral code - https://ts.la/richard11209

 

[John Larkin]

On Mon, 31 Jul 2023 22:22:45 -0700 (PDT), Ricky
<gnuarm.deletethisbit@gmail.com> wrote:

On Tuesday, August 1, 2023 at 12:29:59?AM UTC-4, John Larkin wrote:
On Mon, 31 Jul 2023 19:10:32 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:
On Monday, July 31, 2023 at 6:57:50?PM UTC-4, John Larkin wrote:
On Mon, 31 Jul 2023 15:10:02 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:
On Monday, July 31, 2023 at 3:14:46?PM UTC-4, Joerg wrote:
On 7/22/23 1:43 PM, Ricky wrote:
On Saturday, July 22, 2023 at 4:33:25?PM UTC-4, John Larkin wrote:
On Sat, 22 Jul 2023 13:17:35 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:

I took a class many years ago, where they talked about creating separate power and ground planes for the analog and digital circuitry on a board. ...


For the vast majority of situations that is a bad idea. Often tought by
acedemians who never really designed anything meaningful for industry,
inclusing some at our university.

\"Acedemians\" such as the chip designers? I guess their chips are not assembled onto boards for qualification.


Of course, the ground planes would be joined at one location, typically under the chip that had both analog and digital signals, like an ADC or DAC.
And like John said, of course that chip is the only one in the universe
that needs access to two or more of the grounds

The minute there is one more device like that the whole concept goes
kablouie.

That simply shows you don\'t understand the concept. Larkin says he uses the same idea. He simply rationalizes it as being different by saying he only cuts the area on \"three sides\" rather than talking about how they are connected.
Pot of maybe a thousand board designs, I think I have done that twice,
both times for boards with thermocouple inputs and high power drivers
nearby. Just diverting some ground-plane currents around a sheltered
niche.

You are ignoring that each chip which needs such a scheme can have its own analog ground area. Or, if the two chips can be placed side by side, they can share the connection between the common analog and digital ground planes. If neither is possible, then, no, this won\'t work. But then there are exactly zero techniques that work for every situation. In particular, the single, board wide ground area is not the best approach for some designs.


The high speed digital signals would be routed anywhere other than over the analog ground planes, of course. Some people are telling me this is a bad idea, as if I have totally separate ground planes.

Any comments?
Almost always best is one solid ground plane for everything, bolted to
the metal case through every available spacer and bracket and
connector shell. We standardize on layer 2 for the ground plane, and
occasioanlly also layer 5 (of 6) mostly to keep the copper balanced
when we don\'t need a bunch of power planes..

Handle any microvolt ground loops properly of course.

There\'s no reason for any two grounds to be at different potentials.

The IC people think *their* single chip is the center of the universe,
and that the two system grounds should only meet under their single
chip.

Hmmm... Why would two ground planes be at different potentials if they are connected? Perhaps you missed where I said, \"joined at one location\".

Think of two grounds as a dipole. Yeah, they are connected somewhere in
the center but in RF terms that hardly means anything. Case in point:
All the yagi antennas I ever built have a driven element that is one
contiguous aluminum tube, no separation in the middle. Yet they radiate
and receive as calculated. When you look at the gamma match concept I
use to feed those it might become more clear where disaster can strike
in a split ground system:

https://www.electronics-notes.com/articles/antennas-propagation/antenna-theory/antenna-gamma-impedance-matching.php

Another (noisy) IC, transistor stage or whatever somewhere off center
connecting to one of the ground planes will make the whole contraption
radiate. That can cause you to fail radiated and sometimes even
conducted EMC. It also \"receives\", which may cause you to fail the
susceptibility test which is nowadays part of the EMC test protocol.

I don\'t know why you are trying to make antennas on the ground plane. There should be very, very little current flowing through the connection between the analog and digital ground areas, so very insignificant radiation.

As for susceptibility, how does the connection make the design more susceptible? Even an intact ground plane is susceptible to received radiation. It produces very little voltage because of the low resistance of the plane. Two connected planes can be connected with as low a resistance as desired, again, minimizing the induced voltage.


The idea is that some circuitry, such as a switching power converter or a power hungry IC, puts large currents in the ground plane, which do not limit themselves to the immediate area under that circuit.

Connecting the two ground planes at one spot, limits the impact of these currents to the digital plane.

In practice it usually doesn\'t. RF always tries to find another path
around it, and finds it.

You aren\'t making sense. What RF from what source? What other paths?


Of course, there is always more to a design than one such detail. This still requires the elimination of ground loops from other ground connections, such as off board.

Exactly, and in practice you often can\'t. Outside stuff has to connect
to your system. Mains power, protective earth, some sensors, maybe a
keyboard, a touch screen that by its very nature can be touched by a
conductive human finger, and so on.

I\'ve been on the beat for many decades. In all that time I never saw a
mixed-signal design with a split ground that worked reliably. Many times
I was called in as a consultant to \"make it work\", upon which I removed
all the ground splits. Often against vehement protests on the part of
client engineers. My own designs never had split grounds and they always
worked.

I can\'t speak to designs I know nothing of. When you talk about \"split planes\", you make it sound like they are not connected. My concept is exactly like the scheme that Larkin uses. We only differ by how much connection is made between them. Larkin is simply afraid to extend the scheme to its fullest, practical use.


There are very few exceptions. In sensitive audio setups an occasional
split can make sense but in my experience even there it\'s rare.

Ok, so then you agree with the concept. Thank you.


Then
there are safety rules. For example, in med-tech we must often maintain
full defibrillator-proof isolation when used in cardiac situations,
meaning it has to withstand 5kV. There the grounds aren\'t connected
anywhere.

And yet, you manage to not have excessive noise, yes?

You seem to actually be saying all methods work. Ok, I won\'t disagree. I simply find the use of borders around noisy, or sensitive circuits, is a good way to isolate noise. You seem to agree, but, like Larkin, get all wigged out by talking about this being a reasonable idea, even though you eventually admit that it works.

I think enough has been said about this. There\'s nothing new in your post. You are agreeing with Larkin, who also agrees with me. You both simply have trouble admitting that you agree.
Hilarious. I never join \"analog ground\" and \"digital ground\" under a
chip, much less many chips. In fact, I never have two grounds.

I don\'t have two grounds either. They are joined to form a single ground, just like you said you do.
\"They are joined?\" What does that mean? Is a single ground \"joined\" to
itself?

Sounds like new-speak gendering, where one person is \"they.\"

I suppose it should not surprise me that you resort to being snarky about this. You know exactly what I mean. All along, I have talked about two *areas* of the ground plane, joined at an optimal point, so that it is a single ground plane electrically.

Snark? Me?

No, I don\'t know what you mean. Please post a pic of an actual board.

Now, that it is very clear you acknowledge using the same technique, you are trying to hide by not discussing the facts, and playing your usual games.

Picture, please.

This is about the point where you will become offended, saying I am being snarky, and refuse to discuss the actual topic further, or to answer my questions in a meaningful way. That\'s ok. I\'m not expecting anything different.

I posted one.

 

[Ricky]

On Wednesday, August 2, 2023 at 7:49:21 PM UTC-4, John Larkin wrote:

On Mon, 31 Jul 2023 22:22:45 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:
On Tuesday, August 1, 2023 at 12:29:59?AM UTC-4, John Larkin wrote:
On Mon, 31 Jul 2023 19:10:32 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:
On Monday, July 31, 2023 at 6:57:50?PM UTC-4, John Larkin wrote:
On Mon, 31 Jul 2023 15:10:02 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:
On Monday, July 31, 2023 at 3:14:46?PM UTC-4, Joerg wrote:
On 7/22/23 1:43 PM, Ricky wrote:
On Saturday, July 22, 2023 at 4:33:25?PM UTC-4, John Larkin wrote:
On Sat, 22 Jul 2023 13:17:35 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:

I took a class many years ago, where they talked about creating separate power and ground planes for the analog and digital circuitry on a board. ...


For the vast majority of situations that is a bad idea. Often tought by
acedemians who never really designed anything meaningful for industry,
inclusing some at our university.

\"Acedemians\" such as the chip designers? I guess their chips are not assembled onto boards for qualification.


Of course, the ground planes would be joined at one location, typically under the chip that had both analog and digital signals, like an ADC or DAC.
And like John said, of course that chip is the only one in the universe
that needs access to two or more of the grounds

The minute there is one more device like that the whole concept goes
kablouie.

That simply shows you don\'t understand the concept. Larkin says he uses the same idea. He simply rationalizes it as being different by saying he only cuts the area on \"three sides\" rather than talking about how they are connected.
Pot of maybe a thousand board designs, I think I have done that twice,
both times for boards with thermocouple inputs and high power drivers
nearby. Just diverting some ground-plane currents around a sheltered
niche.

You are ignoring that each chip which needs such a scheme can have its own analog ground area. Or, if the two chips can be placed side by side, they can share the connection between the common analog and digital ground planes. If neither is possible, then, no, this won\'t work. But then there are exactly zero techniques that work for every situation. In particular, the single, board wide ground area is not the best approach for some designs.


The high speed digital signals would be routed anywhere other than over the analog ground planes, of course. Some people are telling me this is a bad idea, as if I have totally separate ground planes.

Any comments?
Almost always best is one solid ground plane for everything, bolted to
the metal case through every available spacer and bracket and
connector shell. We standardize on layer 2 for the ground plane, and
occasioanlly also layer 5 (of 6) mostly to keep the copper balanced
when we don\'t need a bunch of power planes..

Handle any microvolt ground loops properly of course.

There\'s no reason for any two grounds to be at different potentials.

The IC people think *their* single chip is the center of the universe,
and that the two system grounds should only meet under their single
chip.

Hmmm... Why would two ground planes be at different potentials if they are connected? Perhaps you missed where I said, \"joined at one location\".

Think of two grounds as a dipole. Yeah, they are connected somewhere in
the center but in RF terms that hardly means anything. Case in point:
All the yagi antennas I ever built have a driven element that is one
contiguous aluminum tube, no separation in the middle. Yet they radiate
and receive as calculated. When you look at the gamma match concept I
use to feed those it might become more clear where disaster can strike
in a split ground system:

https://www.electronics-notes.com/articles/antennas-propagation/antenna-theory/antenna-gamma-impedance-matching.php

Another (noisy) IC, transistor stage or whatever somewhere off center
connecting to one of the ground planes will make the whole contraption
radiate. That can cause you to fail radiated and sometimes even
conducted EMC. It also \"receives\", which may cause you to fail the
susceptibility test which is nowadays part of the EMC test protocol.

I don\'t know why you are trying to make antennas on the ground plane. There should be very, very little current flowing through the connection between the analog and digital ground areas, so very insignificant radiation.

As for susceptibility, how does the connection make the design more susceptible? Even an intact ground plane is susceptible to received radiation. It produces very little voltage because of the low resistance of the plane. Two connected planes can be connected with as low a resistance as desired, again, minimizing the induced voltage.


The idea is that some circuitry, such as a switching power converter or a power hungry IC, puts large currents in the ground plane, which do not limit themselves to the immediate area under that circuit.

Connecting the two ground planes at one spot, limits the impact of these currents to the digital plane.

In practice it usually doesn\'t. RF always tries to find another path
around it, and finds it.

You aren\'t making sense. What RF from what source? What other paths?


Of course, there is always more to a design than one such detail. This still requires the elimination of ground loops from other ground connections, such as off board.

Exactly, and in practice you often can\'t. Outside stuff has to connect
to your system. Mains power, protective earth, some sensors, maybe a
keyboard, a touch screen that by its very nature can be touched by a
conductive human finger, and so on.

I\'ve been on the beat for many decades. In all that time I never saw a
mixed-signal design with a split ground that worked reliably. Many times
I was called in as a consultant to \"make it work\", upon which I removed
all the ground splits. Often against vehement protests on the part of
client engineers. My own designs never had split grounds and they always
worked.

I can\'t speak to designs I know nothing of. When you talk about \"split planes\", you make it sound like they are not connected. My concept is exactly like the scheme that Larkin uses. We only differ by how much connection is made between them. Larkin is simply afraid to extend the scheme to its fullest, practical use.


There are very few exceptions. In sensitive audio setups an occasional
split can make sense but in my experience even there it\'s rare.

Ok, so then you agree with the concept. Thank you.


Then
there are safety rules. For example, in med-tech we must often maintain
full defibrillator-proof isolation when used in cardiac situations,
meaning it has to withstand 5kV. There the grounds aren\'t connected
anywhere.

And yet, you manage to not have excessive noise, yes?

You seem to actually be saying all methods work. Ok, I won\'t disagree. I simply find the use of borders around noisy, or sensitive circuits, is a good way to isolate noise. You seem to agree, but, like Larkin, get all wigged out by talking about this being a reasonable idea, even though you eventually admit that it works.

I think enough has been said about this. There\'s nothing new in your post. You are agreeing with Larkin, who also agrees with me. You both simply have trouble admitting that you agree.
Hilarious. I never join \"analog ground\" and \"digital ground\" under a
chip, much less many chips. In fact, I never have two grounds.

I don\'t have two grounds either. They are joined to form a single ground, just like you said you do.
\"They are joined?\" What does that mean? Is a single ground \"joined\" to
itself?

Sounds like new-speak gendering, where one person is \"they.\"

I suppose it should not surprise me that you resort to being snarky about this. You know exactly what I mean. All along, I have talked about two *areas* of the ground plane, joined at an optimal point, so that it is a single ground plane electrically.
Snark? Me?

No, I don\'t know what you mean. Please post a pic of an actual board.

You have to admit, that sometimes, Larkin is very funny.

Now, that it is very clear you acknowledge using the same technique, you are trying to hide by not discussing the facts, and playing your usual games.
Picture, please.

This is about the point where you will become offended, saying I am being snarky, and refuse to discuss the actual topic further, or to answer my questions in a meaningful way. That\'s ok. I\'m not expecting anything different.
I posted one.

Please explain how it is different from the plane splits I talk about.

--

Rick C.

+++ Get 1,000 miles of free Supercharging
+++ Tesla referral code - https://ts.la/richard11209

 

[John Larkin]

On Wed, 2 Aug 2023 17:56:42 -0700 (PDT), Ricky
<gnuarm.deletethisbit@gmail.com> wrote:

On Wednesday, August 2, 2023 at 7:49:21?PM UTC-4, John Larkin wrote:
On Mon, 31 Jul 2023 22:22:45 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:
On Tuesday, August 1, 2023 at 12:29:59?AM UTC-4, John Larkin wrote:
On Mon, 31 Jul 2023 19:10:32 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:
On Monday, July 31, 2023 at 6:57:50?PM UTC-4, John Larkin wrote:
On Mon, 31 Jul 2023 15:10:02 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:
On Monday, July 31, 2023 at 3:14:46?PM UTC-4, Joerg wrote:
On 7/22/23 1:43 PM, Ricky wrote:
On Saturday, July 22, 2023 at 4:33:25?PM UTC-4, John Larkin wrote:
On Sat, 22 Jul 2023 13:17:35 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:

I took a class many years ago, where they talked about creating separate power and ground planes for the analog and digital circuitry on a board. ...


For the vast majority of situations that is a bad idea. Often tought by
acedemians who never really designed anything meaningful for industry,
inclusing some at our university.

\"Acedemians\" such as the chip designers? I guess their chips are not assembled onto boards for qualification.


Of course, the ground planes would be joined at one location, typically under the chip that had both analog and digital signals, like an ADC or DAC.
And like John said, of course that chip is the only one in the universe
that needs access to two or more of the grounds

The minute there is one more device like that the whole concept goes
kablouie.

That simply shows you don\'t understand the concept. Larkin says he uses the same idea. He simply rationalizes it as being different by saying he only cuts the area on \"three sides\" rather than talking about how they are connected.
Pot of maybe a thousand board designs, I think I have done that twice,
both times for boards with thermocouple inputs and high power drivers
nearby. Just diverting some ground-plane currents around a sheltered
niche.

You are ignoring that each chip which needs such a scheme can have its own analog ground area. Or, if the two chips can be placed side by side, they can share the connection between the common analog and digital ground planes. If neither is possible, then, no, this won\'t work. But then there are exactly zero techniques that work for every situation. In particular, the single, board wide ground area is not the best approach for some designs.


The high speed digital signals would be routed anywhere other than over the analog ground planes, of course. Some people are telling me this is a bad idea, as if I have totally separate ground planes.

Any comments?
Almost always best is one solid ground plane for everything, bolted to
the metal case through every available spacer and bracket and
connector shell. We standardize on layer 2 for the ground plane, and
occasioanlly also layer 5 (of 6) mostly to keep the copper balanced
when we don\'t need a bunch of power planes..

Handle any microvolt ground loops properly of course.

There\'s no reason for any two grounds to be at different potentials.

The IC people think *their* single chip is the center of the universe,
and that the two system grounds should only meet under their single
chip.

Hmmm... Why would two ground planes be at different potentials if they are connected? Perhaps you missed where I said, \"joined at one location\".

Think of two grounds as a dipole. Yeah, they are connected somewhere in
the center but in RF terms that hardly means anything. Case in point:
All the yagi antennas I ever built have a driven element that is one
contiguous aluminum tube, no separation in the middle. Yet they radiate
and receive as calculated. When you look at the gamma match concept I
use to feed those it might become more clear where disaster can strike
in a split ground system:

https://www.electronics-notes.com/articles/antennas-propagation/antenna-theory/antenna-gamma-impedance-matching.php

Another (noisy) IC, transistor stage or whatever somewhere off center
connecting to one of the ground planes will make the whole contraption
radiate. That can cause you to fail radiated and sometimes even
conducted EMC. It also \"receives\", which may cause you to fail the
susceptibility test which is nowadays part of the EMC test protocol.

I don\'t know why you are trying to make antennas on the ground plane. There should be very, very little current flowing through the connection between the analog and digital ground areas, so very insignificant radiation.

As for susceptibility, how does the connection make the design more susceptible? Even an intact ground plane is susceptible to received radiation. It produces very little voltage because of the low resistance of the plane. Two connected planes can be connected with as low a resistance as desired, again, minimizing the induced voltage.


The idea is that some circuitry, such as a switching power converter or a power hungry IC, puts large currents in the ground plane, which do not limit themselves to the immediate area under that circuit.

Connecting the two ground planes at one spot, limits the impact of these currents to the digital plane.

In practice it usually doesn\'t. RF always tries to find another path
around it, and finds it.

You aren\'t making sense. What RF from what source? What other paths?


Of course, there is always more to a design than one such detail. This still requires the elimination of ground loops from other ground connections, such as off board.

Exactly, and in practice you often can\'t. Outside stuff has to connect
to your system. Mains power, protective earth, some sensors, maybe a
keyboard, a touch screen that by its very nature can be touched by a
conductive human finger, and so on.

I\'ve been on the beat for many decades. In all that time I never saw a
mixed-signal design with a split ground that worked reliably. Many times
I was called in as a consultant to \"make it work\", upon which I removed
all the ground splits. Often against vehement protests on the part of
client engineers. My own designs never had split grounds and they always
worked.

I can\'t speak to designs I know nothing of. When you talk about \"split planes\", you make it sound like they are not connected. My concept is exactly like the scheme that Larkin uses. We only differ by how much connection is made between them. Larkin is simply afraid to extend the scheme to its fullest, practical use.


There are very few exceptions. In sensitive audio setups an occasional
split can make sense but in my experience even there it\'s rare.

Ok, so then you agree with the concept. Thank you.


Then
there are safety rules. For example, in med-tech we must often maintain
full defibrillator-proof isolation when used in cardiac situations,
meaning it has to withstand 5kV. There the grounds aren\'t connected
anywhere.

And yet, you manage to not have excessive noise, yes?

You seem to actually be saying all methods work. Ok, I won\'t disagree. I simply find the use of borders around noisy, or sensitive circuits, is a good way to isolate noise. You seem to agree, but, like Larkin, get all wigged out by talking about this being a reasonable idea, even though you eventually admit that it works.

I think enough has been said about this. There\'s nothing new in your post. You are agreeing with Larkin, who also agrees with me. You both simply have trouble admitting that you agree.
Hilarious. I never join \"analog ground\" and \"digital ground\" under a
chip, much less many chips. In fact, I never have two grounds.

I don\'t have two grounds either. They are joined to form a single ground, just like you said you do.
\"They are joined?\" What does that mean? Is a single ground \"joined\" to
itself?

Sounds like new-speak gendering, where one person is \"they.\"

I suppose it should not surprise me that you resort to being snarky about this. You know exactly what I mean. All along, I have talked about two *areas* of the ground plane, joined at an optimal point, so that it is a single ground plane electrically.
Snark? Me?

No, I don\'t know what you mean. Please post a pic of an actual board.

You have to admit, that sometimes, Larkin is very funny.


Now, that it is very clear you acknowledge using the same technique, you are trying to hide by not discussing the facts, and playing your usual games.
Picture, please.

This is about the point where you will become offended, saying I am being snarky, and refuse to discuss the actual topic further, or to answer my questions in a meaningful way. That\'s ok. I\'m not expecting anything different.
I posted one.

Please explain how it is different from the plane splits I talk about.

Show us.

 

[Ricky]

On Wednesday, August 2, 2023 at 9:28:55 PM UTC-4, John Larkin wrote:

On Wed, 2 Aug 2023 17:56:42 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:
On Wednesday, August 2, 2023 at 7:49:21?PM UTC-4, John Larkin wrote:
On Mon, 31 Jul 2023 22:22:45 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:
On Tuesday, August 1, 2023 at 12:29:59?AM UTC-4, John Larkin wrote:
On Mon, 31 Jul 2023 19:10:32 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:
On Monday, July 31, 2023 at 6:57:50?PM UTC-4, John Larkin wrote:
On Mon, 31 Jul 2023 15:10:02 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:
On Monday, July 31, 2023 at 3:14:46?PM UTC-4, Joerg wrote:
On 7/22/23 1:43 PM, Ricky wrote:
On Saturday, July 22, 2023 at 4:33:25?PM UTC-4, John Larkin wrote:
On Sat, 22 Jul 2023 13:17:35 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:

I took a class many years ago, where they talked about creating separate power and ground planes for the analog and digital circuitry on a board. ...


For the vast majority of situations that is a bad idea. Often tought by
acedemians who never really designed anything meaningful for industry,
inclusing some at our university.

\"Acedemians\" such as the chip designers? I guess their chips are not assembled onto boards for qualification.


Of course, the ground planes would be joined at one location, typically under the chip that had both analog and digital signals, like an ADC or DAC.
And like John said, of course that chip is the only one in the universe
that needs access to two or more of the grounds

The minute there is one more device like that the whole concept goes
kablouie.

That simply shows you don\'t understand the concept. Larkin says he uses the same idea. He simply rationalizes it as being different by saying he only cuts the area on \"three sides\" rather than talking about how they are connected.
Pot of maybe a thousand board designs, I think I have done that twice,
both times for boards with thermocouple inputs and high power drivers
nearby. Just diverting some ground-plane currents around a sheltered
niche.

You are ignoring that each chip which needs such a scheme can have its own analog ground area. Or, if the two chips can be placed side by side, they can share the connection between the common analog and digital ground planes. If neither is possible, then, no, this won\'t work. But then there are exactly zero techniques that work for every situation. In particular, the single, board wide ground area is not the best approach for some designs.


The high speed digital signals would be routed anywhere other than over the analog ground planes, of course. Some people are telling me this is a bad idea, as if I have totally separate ground planes.

Any comments?
Almost always best is one solid ground plane for everything, bolted to
the metal case through every available spacer and bracket and
connector shell. We standardize on layer 2 for the ground plane, and
occasioanlly also layer 5 (of 6) mostly to keep the copper balanced
when we don\'t need a bunch of power planes..

Handle any microvolt ground loops properly of course.

There\'s no reason for any two grounds to be at different potentials.

The IC people think *their* single chip is the center of the universe,
and that the two system grounds should only meet under their single
chip.

Hmmm... Why would two ground planes be at different potentials if they are connected? Perhaps you missed where I said, \"joined at one location\".

Think of two grounds as a dipole. Yeah, they are connected somewhere in
the center but in RF terms that hardly means anything. Case in point:
All the yagi antennas I ever built have a driven element that is one
contiguous aluminum tube, no separation in the middle. Yet they radiate
and receive as calculated. When you look at the gamma match concept I
use to feed those it might become more clear where disaster can strike
in a split ground system:

https://www.electronics-notes.com/articles/antennas-propagation/antenna-theory/antenna-gamma-impedance-matching.php

Another (noisy) IC, transistor stage or whatever somewhere off center
connecting to one of the ground planes will make the whole contraption
radiate. That can cause you to fail radiated and sometimes even
conducted EMC. It also \"receives\", which may cause you to fail the
susceptibility test which is nowadays part of the EMC test protocol.

I don\'t know why you are trying to make antennas on the ground plane. There should be very, very little current flowing through the connection between the analog and digital ground areas, so very insignificant radiation.

As for susceptibility, how does the connection make the design more susceptible? Even an intact ground plane is susceptible to received radiation. It produces very little voltage because of the low resistance of the plane. Two connected planes can be connected with as low a resistance as desired, again, minimizing the induced voltage.


The idea is that some circuitry, such as a switching power converter or a power hungry IC, puts large currents in the ground plane, which do not limit themselves to the immediate area under that circuit.

Connecting the two ground planes at one spot, limits the impact of these currents to the digital plane.

In practice it usually doesn\'t. RF always tries to find another path
around it, and finds it.

You aren\'t making sense. What RF from what source? What other paths?


Of course, there is always more to a design than one such detail. This still requires the elimination of ground loops from other ground connections, such as off board.

Exactly, and in practice you often can\'t. Outside stuff has to connect
to your system. Mains power, protective earth, some sensors, maybe a
keyboard, a touch screen that by its very nature can be touched by a
conductive human finger, and so on.

I\'ve been on the beat for many decades. In all that time I never saw a
mixed-signal design with a split ground that worked reliably. Many times
I was called in as a consultant to \"make it work\", upon which I removed
all the ground splits. Often against vehement protests on the part of
client engineers. My own designs never had split grounds and they always
worked.

I can\'t speak to designs I know nothing of. When you talk about \"split planes\", you make it sound like they are not connected. My concept is exactly like the scheme that Larkin uses. We only differ by how much connection is made between them. Larkin is simply afraid to extend the scheme to its fullest, practical use.


There are very few exceptions. In sensitive audio setups an occasional
split can make sense but in my experience even there it\'s rare.

Ok, so then you agree with the concept. Thank you.


Then
there are safety rules. For example, in med-tech we must often maintain
full defibrillator-proof isolation when used in cardiac situations,
meaning it has to withstand 5kV. There the grounds aren\'t connected
anywhere.

And yet, you manage to not have excessive noise, yes?

You seem to actually be saying all methods work. Ok, I won\'t disagree. I simply find the use of borders around noisy, or sensitive circuits, is a good way to isolate noise. You seem to agree, but, like Larkin, get all wigged out by talking about this being a reasonable idea, even though you eventually admit that it works.

I think enough has been said about this. There\'s nothing new in your post. You are agreeing with Larkin, who also agrees with me. You both simply have trouble admitting that you agree.
Hilarious. I never join \"analog ground\" and \"digital ground\" under a
chip, much less many chips. In fact, I never have two grounds.

I don\'t have two grounds either. They are joined to form a single ground, just like you said you do.
\"They are joined?\" What does that mean? Is a single ground \"joined\" to
itself?

Sounds like new-speak gendering, where one person is \"they.\"

I suppose it should not surprise me that you resort to being snarky about this. You know exactly what I mean. All along, I have talked about two *areas* of the ground plane, joined at an optimal point, so that it is a single ground plane electrically.
Snark? Me?

No, I don\'t know what you mean. Please post a pic of an actual board.

You have to admit, that sometimes, Larkin is very funny.


Now, that it is very clear you acknowledge using the same technique, you are trying to hide by not discussing the facts, and playing your usual games.
Picture, please.

This is about the point where you will become offended, saying I am being snarky, and refuse to discuss the actual topic further, or to answer my questions in a meaningful way. That\'s ok. I\'m not expecting anything different.
I posted one.

Please explain how it is different from the plane splits I talk about.
Show us.

If you can\'t understand what I\'ve written, why have you been arguing so long that I\'m wrong? My design is largely like yours, but the two areas are separated by a 0.05\" gap, connected by a 0.4 inches wide join.

Everyone can see easily that you don\'t really want to discuss this. You are trying to say that your isolated ground area is not the same as mine. But there is no significant difference. The isolated area is virtually all analog with a max frequency (of interest) of 20 kHz. The only digital signals are control lines to configure the circuit through analog switches. The digital lines are set, and not changed until the analog circuit needs to be reconfigured.

Breaking out the analog area with a connected ground, but surrounded by a moat, just as in your design, prevents any stray ground currents from flowing through the analog area, introducing voltage drop in the analog region. This is a daughter board with the off board, ground connection in the same area as the analog/digital join. It works very well.

Instead of playing games, why don\'t you explain why your isolated ground area is ok, when you seem to claim the concept is fundamentally flawed? I know that others have said the concept is fundamentally flawed. You seem to have said that too, before you said that you also use the idea.

--

Rick C.

---- Get 1,000 miles of free Supercharging
---- Tesla referral code - https://ts.la/richard11209

 

[John Larkin]

On Wed, 2 Aug 2023 21:10:52 -0700 (PDT), Ricky
<gnuarm.deletethisbit@gmail.com> wrote:

On Wednesday, August 2, 2023 at 9:28:55?PM UTC-4, John Larkin wrote:
On Wed, 2 Aug 2023 17:56:42 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:
On Wednesday, August 2, 2023 at 7:49:21?PM UTC-4, John Larkin wrote:
On Mon, 31 Jul 2023 22:22:45 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:
On Tuesday, August 1, 2023 at 12:29:59?AM UTC-4, John Larkin wrote:
On Mon, 31 Jul 2023 19:10:32 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:
On Monday, July 31, 2023 at 6:57:50?PM UTC-4, John Larkin wrote:
On Mon, 31 Jul 2023 15:10:02 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:
On Monday, July 31, 2023 at 3:14:46?PM UTC-4, Joerg wrote:
On 7/22/23 1:43 PM, Ricky wrote:
On Saturday, July 22, 2023 at 4:33:25?PM UTC-4, John Larkin wrote:
On Sat, 22 Jul 2023 13:17:35 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:

I took a class many years ago, where they talked about creating separate power and ground planes for the analog and digital circuitry on a board. ...


For the vast majority of situations that is a bad idea. Often tought by
acedemians who never really designed anything meaningful for industry,
inclusing some at our university.

\"Acedemians\" such as the chip designers? I guess their chips are not assembled onto boards for qualification.


Of course, the ground planes would be joined at one location, typically under the chip that had both analog and digital signals, like an ADC or DAC.
And like John said, of course that chip is the only one in the universe
that needs access to two or more of the grounds

The minute there is one more device like that the whole concept goes
kablouie.

That simply shows you don\'t understand the concept. Larkin says he uses the same idea. He simply rationalizes it as being different by saying he only cuts the area on \"three sides\" rather than talking about how they are connected.
Pot of maybe a thousand board designs, I think I have done that twice,
both times for boards with thermocouple inputs and high power drivers
nearby. Just diverting some ground-plane currents around a sheltered
niche.

You are ignoring that each chip which needs such a scheme can have its own analog ground area. Or, if the two chips can be placed side by side, they can share the connection between the common analog and digital ground planes. If neither is possible, then, no, this won\'t work. But then there are exactly zero techniques that work for every situation. In particular, the single, board wide ground area is not the best approach for some designs.


The high speed digital signals would be routed anywhere other than over the analog ground planes, of course. Some people are telling me this is a bad idea, as if I have totally separate ground planes.

Any comments?
Almost always best is one solid ground plane for everything, bolted to
the metal case through every available spacer and bracket and
connector shell. We standardize on layer 2 for the ground plane, and
occasioanlly also layer 5 (of 6) mostly to keep the copper balanced
when we don\'t need a bunch of power planes..

Handle any microvolt ground loops properly of course.

There\'s no reason for any two grounds to be at different potentials.

The IC people think *their* single chip is the center of the universe,
and that the two system grounds should only meet under their single
chip.

Hmmm... Why would two ground planes be at different potentials if they are connected? Perhaps you missed where I said, \"joined at one location\".

Think of two grounds as a dipole. Yeah, they are connected somewhere in
the center but in RF terms that hardly means anything. Case in point:
All the yagi antennas I ever built have a driven element that is one
contiguous aluminum tube, no separation in the middle. Yet they radiate
and receive as calculated. When you look at the gamma match concept I
use to feed those it might become more clear where disaster can strike
in a split ground system:

https://www.electronics-notes.com/articles/antennas-propagation/antenna-theory/antenna-gamma-impedance-matching.php

Another (noisy) IC, transistor stage or whatever somewhere off center
connecting to one of the ground planes will make the whole contraption
radiate. That can cause you to fail radiated and sometimes even
conducted EMC. It also \"receives\", which may cause you to fail the
susceptibility test which is nowadays part of the EMC test protocol.

I don\'t know why you are trying to make antennas on the ground plane. There should be very, very little current flowing through the connection between the analog and digital ground areas, so very insignificant radiation.

As for susceptibility, how does the connection make the design more susceptible? Even an intact ground plane is susceptible to received radiation. It produces very little voltage because of the low resistance of the plane. Two connected planes can be connected with as low a resistance as desired, again, minimizing the induced voltage.


The idea is that some circuitry, such as a switching power converter or a power hungry IC, puts large currents in the ground plane, which do not limit themselves to the immediate area under that circuit.

Connecting the two ground planes at one spot, limits the impact of these currents to the digital plane.

In practice it usually doesn\'t. RF always tries to find another path
around it, and finds it.

You aren\'t making sense. What RF from what source? What other paths?


Of course, there is always more to a design than one such detail. This still requires the elimination of ground loops from other ground connections, such as off board.

Exactly, and in practice you often can\'t. Outside stuff has to connect
to your system. Mains power, protective earth, some sensors, maybe a
keyboard, a touch screen that by its very nature can be touched by a
conductive human finger, and so on.

I\'ve been on the beat for many decades. In all that time I never saw a
mixed-signal design with a split ground that worked reliably. Many times
I was called in as a consultant to \"make it work\", upon which I removed
all the ground splits. Often against vehement protests on the part of
client engineers. My own designs never had split grounds and they always
worked.

I can\'t speak to designs I know nothing of. When you talk about \"split planes\", you make it sound like they are not connected. My concept is exactly like the scheme that Larkin uses. We only differ by how much connection is made between them. Larkin is simply afraid to extend the scheme to its fullest, practical use.


There are very few exceptions. In sensitive audio setups an occasional
split can make sense but in my experience even there it\'s rare.

Ok, so then you agree with the concept. Thank you.


Then
there are safety rules. For example, in med-tech we must often maintain
full defibrillator-proof isolation when used in cardiac situations,
meaning it has to withstand 5kV. There the grounds aren\'t connected
anywhere.

And yet, you manage to not have excessive noise, yes?

You seem to actually be saying all methods work. Ok, I won\'t disagree. I simply find the use of borders around noisy, or sensitive circuits, is a good way to isolate noise. You seem to agree, but, like Larkin, get all wigged out by talking about this being a reasonable idea, even though you eventually admit that it works.

I think enough has been said about this. There\'s nothing new in your post. You are agreeing with Larkin, who also agrees with me. You both simply have trouble admitting that you agree.
Hilarious. I never join \"analog ground\" and \"digital ground\" under a
chip, much less many chips. In fact, I never have two grounds.

I don\'t have two grounds either. They are joined to form a single ground, just like you said you do.
\"They are joined?\" What does that mean? Is a single ground \"joined\" to
itself?

Sounds like new-speak gendering, where one person is \"they.\"

I suppose it should not surprise me that you resort to being snarky about this. You know exactly what I mean. All along, I have talked about two *areas* of the ground plane, joined at an optimal point, so that it is a single ground plane electrically.
Snark? Me?

No, I don\'t know what you mean. Please post a pic of an actual board.

You have to admit, that sometimes, Larkin is very funny.


Now, that it is very clear you acknowledge using the same technique, you are trying to hide by not discussing the facts, and playing your usual games.
Picture, please.

This is about the point where you will become offended, saying I am being snarky, and refuse to discuss the actual topic further, or to answer my questions in a meaningful way. That\'s ok. I\'m not expecting anything different.
I posted one.

Please explain how it is different from the plane splits I talk about.
Show us.

If you can\'t understand what I\'ve written, why have you been arguing so long that I\'m wrong? My design is largely like yours, but the two areas are separated by a 0.05\" gap, connected by a 0.4 inches wide join.

Everyone can see easily that you don\'t really want to discuss this. You are trying to say that your isolated ground area is not the same as mine. But there is no significant difference. The isolated area is virtually all analog with a max frequency (of interest) of 20 kHz. The only digital signals are control lines to configure the circuit through analog switches. The digital lines are set, and not changed until the analog circuit needs to be reconfigured.

Breaking out the analog area with a connected ground, but surrounded by a moat, just as in your design, prevents any stray ground currents from flowing through the analog area, introducing voltage drop in the analog region. This is a daughter board with the off board, ground connection in the same area as the analog/digital join. It works very well.

Instead of playing games, why don\'t you explain why your isolated ground area is ok, when you seem to claim the concept is fundamentally flawed? I know that others have said the concept is fundamentally flawed. You seem to have said that too, before you said that you also use the idea.

All hat, no horse. Show us a board.

 

[Anthony William Sloman]

On Friday, August 4, 2023 at 1:09:57 AM UTC+10, John Larkin wrote:

On Wed, 2 Aug 2023 21:10:52 -0700 (PDT), Ricky <gnuarm.del...@gmail.com> wrote:
On Wednesday, August 2, 2023 at 9:28:55?PM UTC-4, John Larkin wrote:
On Wed, 2 Aug 2023 17:56:42 -0700 (PDT), Ricky <gnuarm.del...@gmail.com> wrote:
On Wednesday, August 2, 2023 at 7:49:21?PM UTC-4, John Larkin wrote:
On Mon, 31 Jul 2023 22:22:45 -0700 (PDT), Ricky <gnuarm.del...@gmail.com> wrote:
On Tuesday, August 1, 2023 at 12:29:59?AM UTC-4, John Larkin wrote:
On Mon, 31 Jul 2023 19:10:32 -0700 (PDT), Ricky <gnuarm.del...@gmail.com> wrote:
On Monday, July 31, 2023 at 6:57:50?PM UTC-4, John Larkin wrote:
On Mon, 31 Jul 2023 15:10:02 -0700 (PDT), Ricky <gnuarm.del....@gmail.com> wrote:
On Monday, July 31, 2023 at 3:14:46?PM UTC-4, Joerg wrote:
On 7/22/23 1:43 PM, Ricky wrote:
On Saturday, July 22, 2023 at 4:33:25?PM UTC-4, John Larkin wrote:
On Sat, 22 Jul 2023 13:17:35 -0700 (PDT), Ricky <gnuarm.del...@gmail.com> wrote:

<snip>

Breaking out the analog area with a connected ground, but surrounded by a moat, just as in your design, prevents any stray ground currents from flowing through the analog area, introducing voltage drop in the analog region.. This is a daughter board with the off board, ground connection in the same area as the analog/digital join. It works very well.

Instead of playing games, why don\'t you explain why your isolated ground area is ok, when you seem to claim the concept is fundamentally flawed? I know that others have said the concept is fundamentally flawed. You seem to have said that too, before you said that you also use the idea.

All hat, no horse. Show us a board.

John Larkin can\'t talk about why he designed his boards to turn out that way that they did - probably because design is an intellectual process and he doesn\'t understand what he is doing - so he wants people to show him images.

--
Bill Sloman, Sydney

 

[Ricky]

On Thursday, August 3, 2023 at 11:09:57 AM UTC-4, John Larkin wrote:

On Wed, 2 Aug 2023 21:10:52 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:
On Wednesday, August 2, 2023 at 9:28:55?PM UTC-4, John Larkin wrote:
On Wed, 2 Aug 2023 17:56:42 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:
On Wednesday, August 2, 2023 at 7:49:21?PM UTC-4, John Larkin wrote:
On Mon, 31 Jul 2023 22:22:45 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:
On Tuesday, August 1, 2023 at 12:29:59?AM UTC-4, John Larkin wrote:
On Mon, 31 Jul 2023 19:10:32 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:
On Monday, July 31, 2023 at 6:57:50?PM UTC-4, John Larkin wrote:
On Mon, 31 Jul 2023 15:10:02 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:
On Monday, July 31, 2023 at 3:14:46?PM UTC-4, Joerg wrote:
On 7/22/23 1:43 PM, Ricky wrote:
On Saturday, July 22, 2023 at 4:33:25?PM UTC-4, John Larkin wrote:
On Sat, 22 Jul 2023 13:17:35 -0700 (PDT), Ricky
gnuarm.del...@gmail.com> wrote:

I took a class many years ago, where they talked about creating separate power and ground planes for the analog and digital circuitry on a board. ...


For the vast majority of situations that is a bad idea. Often tought by
acedemians who never really designed anything meaningful for industry,
inclusing some at our university.

\"Acedemians\" such as the chip designers? I guess their chips are not assembled onto boards for qualification.


Of course, the ground planes would be joined at one location, typically under the chip that had both analog and digital signals, like an ADC or DAC.
And like John said, of course that chip is the only one in the universe
that needs access to two or more of the grounds

The minute there is one more device like that the whole concept goes
kablouie.

That simply shows you don\'t understand the concept. Larkin says he uses the same idea. He simply rationalizes it as being different by saying he only cuts the area on \"three sides\" rather than talking about how they are connected.
Pot of maybe a thousand board designs, I think I have done that twice,
both times for boards with thermocouple inputs and high power drivers
nearby. Just diverting some ground-plane currents around a sheltered
niche.

You are ignoring that each chip which needs such a scheme can have its own analog ground area. Or, if the two chips can be placed side by side, they can share the connection between the common analog and digital ground planes. If neither is possible, then, no, this won\'t work. But then there are exactly zero techniques that work for every situation. In particular, the single, board wide ground area is not the best approach for some designs.


The high speed digital signals would be routed anywhere other than over the analog ground planes, of course. Some people are telling me this is a bad idea, as if I have totally separate ground planes.

Any comments?
Almost always best is one solid ground plane for everything, bolted to
the metal case through every available spacer and bracket and
connector shell. We standardize on layer 2 for the ground plane, and
occasioanlly also layer 5 (of 6) mostly to keep the copper balanced
when we don\'t need a bunch of power planes..

Handle any microvolt ground loops properly of course.

There\'s no reason for any two grounds to be at different potentials.

The IC people think *their* single chip is the center of the universe,
and that the two system grounds should only meet under their single
chip.

Hmmm... Why would two ground planes be at different potentials if they are connected? Perhaps you missed where I said, \"joined at one location\".

Think of two grounds as a dipole. Yeah, they are connected somewhere in
the center but in RF terms that hardly means anything. Case in point:
All the yagi antennas I ever built have a driven element that is one
contiguous aluminum tube, no separation in the middle. Yet they radiate
and receive as calculated. When you look at the gamma match concept I
use to feed those it might become more clear where disaster can strike
in a split ground system:

https://www.electronics-notes.com/articles/antennas-propagation/antenna-theory/antenna-gamma-impedance-matching.php

Another (noisy) IC, transistor stage or whatever somewhere off center
connecting to one of the ground planes will make the whole contraption
radiate. That can cause you to fail radiated and sometimes even
conducted EMC. It also \"receives\", which may cause you to fail the
susceptibility test which is nowadays part of the EMC test protocol.

I don\'t know why you are trying to make antennas on the ground plane. There should be very, very little current flowing through the connection between the analog and digital ground areas, so very insignificant radiation.

As for susceptibility, how does the connection make the design more susceptible? Even an intact ground plane is susceptible to received radiation. It produces very little voltage because of the low resistance of the plane. Two connected planes can be connected with as low a resistance as desired, again, minimizing the induced voltage.


The idea is that some circuitry, such as a switching power converter or a power hungry IC, puts large currents in the ground plane, which do not limit themselves to the immediate area under that circuit.

Connecting the two ground planes at one spot, limits the impact of these currents to the digital plane.

In practice it usually doesn\'t. RF always tries to find another path
around it, and finds it.

You aren\'t making sense. What RF from what source? What other paths?


Of course, there is always more to a design than one such detail. This still requires the elimination of ground loops from other ground connections, such as off board.

Exactly, and in practice you often can\'t. Outside stuff has to connect
to your system. Mains power, protective earth, some sensors, maybe a
keyboard, a touch screen that by its very nature can be touched by a
conductive human finger, and so on.

I\'ve been on the beat for many decades. In all that time I never saw a
mixed-signal design with a split ground that worked reliably. Many times
I was called in as a consultant to \"make it work\", upon which I removed
all the ground splits. Often against vehement protests on the part of
client engineers. My own designs never had split grounds and they always
worked.

I can\'t speak to designs I know nothing of. When you talk about \"split planes\", you make it sound like they are not connected. My concept is exactly like the scheme that Larkin uses. We only differ by how much connection is made between them. Larkin is simply afraid to extend the scheme to its fullest, practical use.


There are very few exceptions. In sensitive audio setups an occasional
split can make sense but in my experience even there it\'s rare.

Ok, so then you agree with the concept. Thank you.


Then
there are safety rules. For example, in med-tech we must often maintain
full defibrillator-proof isolation when used in cardiac situations,
meaning it has to withstand 5kV. There the grounds aren\'t connected
anywhere.

And yet, you manage to not have excessive noise, yes?

You seem to actually be saying all methods work. Ok, I won\'t disagree. I simply find the use of borders around noisy, or sensitive circuits, is a good way to isolate noise. You seem to agree, but, like Larkin, get all wigged out by talking about this being a reasonable idea, even though you eventually admit that it works.

I think enough has been said about this. There\'s nothing new in your post. You are agreeing with Larkin, who also agrees with me. You both simply have trouble admitting that you agree.
Hilarious. I never join \"analog ground\" and \"digital ground\" under a
chip, much less many chips. In fact, I never have two grounds..

I don\'t have two grounds either. They are joined to form a single ground, just like you said you do.
\"They are joined?\" What does that mean? Is a single ground \"joined\" to
itself?

Sounds like new-speak gendering, where one person is \"they.\"

I suppose it should not surprise me that you resort to being snarky about this. You know exactly what I mean. All along, I have talked about two *areas* of the ground plane, joined at an optimal point, so that it is a single ground plane electrically.
Snark? Me?

No, I don\'t know what you mean. Please post a pic of an actual board.

You have to admit, that sometimes, Larkin is very funny.


Now, that it is very clear you acknowledge using the same technique, you are trying to hide by not discussing the facts, and playing your usual games.
Picture, please.

This is about the point where you will become offended, saying I am being snarky, and refuse to discuss the actual topic further, or to answer my questions in a meaningful way. That\'s ok. I\'m not expecting anything different.
I posted one.

Please explain how it is different from the plane splits I talk about..
Show us.

If you can\'t understand what I\'ve written, why have you been arguing so long that I\'m wrong? My design is largely like yours, but the two areas are separated by a 0.05\" gap, connected by a 0.4 inches wide join.

Everyone can see easily that you don\'t really want to discuss this. You are trying to say that your isolated ground area is not the same as mine. But there is no significant difference. The isolated area is virtually all analog with a max frequency (of interest) of 20 kHz. The only digital signals are control lines to configure the circuit through analog switches. The digital lines are set, and not changed until the analog circuit needs to be reconfigured.

Breaking out the analog area with a connected ground, but surrounded by a moat, just as in your design, prevents any stray ground currents from flowing through the analog area, introducing voltage drop in the analog region.. This is a daughter board with the off board, ground connection in the same area as the analog/digital join. It works very well.

Instead of playing games, why don\'t you explain why your isolated ground area is ok, when you seem to claim the concept is fundamentally flawed? I know that others have said the concept is fundamentally flawed. You seem to have said that too, before you said that you also use the idea.
All hat, no horse. Show us a board.

Larkin is frozen in place. He doesn\'t understand words. He only knows pictures.

Whatever. He has very clearly been using the same technique that I\'ve described. So when he says it can\'t work, he is talking about his own designs. It\'s not surprising that he can\'t explain his designs. He has said all along that he seldom actually designs circuits, rather than experiment with them until he can make them work \"good enough\". That\'s likely why he doesn\'t understand he is using exactly the same technique I\'m talking about.

--

Rick C.

---+ Get 1,000 miles of free Supercharging
---+ Tesla referral code - https://ts.la/richard11209