new GaN fet...

[server]

On Thu, 03 Mar 2022 08:25:27 -0800, jlarkin@highlandsniptechnology.com
wrote:

On Thu, 3 Mar 2022 11:12:30 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 06:32:58 +0100, Gerhard Hoffmann <dk4xp@arcor.de
wrote:

Am 03.03.22 um 05:54 schrieb jlarkin@highlandsniptechnology.com:
On Wed, 2 Mar 2022 20:27:20 -0800 (PST), Rich S
richsulinengineer@gmail.com> wrote:

Those loadpull charts on page 5 are a mess,
unreadable, If this is what its like, then
No wonder a lot of RF guys retire unexpectedly.

RF lives in the dark ages. We need Spice models.

Don\'t mke me laugh so hard. Spice IS the dark ages.
What we need is AWR or ADS design kits.

Gerhard

What\'s wrong with knowing all the voltages and currents as a function
of time?

If you know that, you know all the RF stuff. That doesn\'t work in
reverse.

And what\'s wrong with knowing drain current as a function of gate
voltage? RF data sheets usually say \"turn the trimpot until the RF
comes out.\"

I wonder how people generate those \"design kits\" if they don\'t know
the basic electrical properties of the part. Maybe it\'s like \"load
pull\" engineering.


They probably make about eight of them over the lifetime of the part, so
statistics are hard to come by.

Cheers

Phil Hobbs

Rf is a strange world. I think its traditions pre-date computers, so
they emphasize analytical, necessarily linear, ideas like s-params and
Smith charts. Things that could be sort-of handled with pencils and
slide rules.

The nonlinear stuff became load-pull, basically documenting a few
bench tests.

The EPC GaN fets have Spice models and LT Spice examples, probably
because the intended market is switching power supplies.

The Cree SiC fets have Spice models, for the same reason.

So different semiconductor companies have different cultures, and
declare their parts to be time domain (switching) parts or frequency
domain (RF) parts, and cut their market roughly in half.

If they spec a part for narrowband RF, they want even fewer customers.

We\'re trying to use a Hittite RF switch to route time-domain signals,
arbitrary waveforms and pulses in a laser modulator. The data sheet is
terrible. I\'m waiting to see if their support people really understand
the part. Like, what\'s the capacitance of the switch control pin? Why
is the low frequency limit 100 MHz?

There might be uses for RF switches in electro-optical gadgets. We\'re
measuring stuff.

We discovered that, for the switch under consideration, \"reflective
switch\" means that it shorts the deselected input port! I suppose
that\'s technically correct. Some \"reflective\" switches open the
unselected port. In the RF world, I guess it\'s all the same.







--

I yam what I yam - Popeye

 

[Phil Hobbs]

jlarkin@highlandsniptechnology.com wrote:

On Thu, 03 Mar 2022 08:25:27 -0800, jlarkin@highlandsniptechnology.com
wrote:

On Thu, 3 Mar 2022 11:12:30 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 06:32:58 +0100, Gerhard Hoffmann <dk4xp@arcor.de
wrote:

Am 03.03.22 um 05:54 schrieb jlarkin@highlandsniptechnology.com:
On Wed, 2 Mar 2022 20:27:20 -0800 (PST), Rich S
richsulinengineer@gmail.com> wrote:

Those loadpull charts on page 5 are a mess,
unreadable, If this is what its like, then
No wonder a lot of RF guys retire unexpectedly.

RF lives in the dark ages. We need Spice models.

Don\'t mke me laugh so hard. Spice IS the dark ages.
What we need is AWR or ADS design kits.

Gerhard

What\'s wrong with knowing all the voltages and currents as a function
of time?

If you know that, you know all the RF stuff. That doesn\'t work in
reverse.

And what\'s wrong with knowing drain current as a function of gate
voltage? RF data sheets usually say \"turn the trimpot until the RF
comes out.\"

I wonder how people generate those \"design kits\" if they don\'t know
the basic electrical properties of the part. Maybe it\'s like \"load
pull\" engineering.


They probably make about eight of them over the lifetime of the part, so
statistics are hard to come by.

Cheers

Phil Hobbs

Rf is a strange world. I think its traditions pre-date computers, so
they emphasize analytical, necessarily linear, ideas like s-params and
Smith charts. Things that could be sort-of handled with pencils and
slide rules.

The nonlinear stuff became load-pull, basically documenting a few
bench tests.

The EPC GaN fets have Spice models and LT Spice examples, probably
because the intended market is switching power supplies.

The Cree SiC fets have Spice models, for the same reason.


So different semiconductor companies have different cultures, and
declare their parts to be time domain (switching) parts or frequency
domain (RF) parts, and cut their market roughly in half.

If they spec a part for narrowband RF, they want even fewer customers.

We\'re trying to use a Hittite RF switch to route time-domain signals,
arbitrary waveforms and pulses in a laser modulator. The data sheet is
terrible. I\'m waiting to see if their support people really understand
the part. Like, what\'s the capacitance of the switch control pin? Why
is the low frequency limit 100 MHz?

There might be uses for RF switches in electro-optical gadgets. We\'re
measuring stuff.

We discovered that, for the switch under consideration, \"reflective
switch\" means that it shorts the deselected input port! I suppose
that\'s technically correct. Some \"reflective\" switches open the
unselected port. In the RF world, I guess it\'s all the same.

At 4 GHz, a short becomes an open if you hang a two-inch cable on it.
RF folks are very fond of that sort of pure frequency domain trick.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Tom Gardner]

On 03/03/22 16:25, jlarkin@highlandsniptechnology.com wrote:

On Thu, 3 Mar 2022 11:12:30 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 06:32:58 +0100, Gerhard Hoffmann <dk4xp@arcor.de
wrote:

Am 03.03.22 um 05:54 schrieb jlarkin@highlandsniptechnology.com:
On Wed, 2 Mar 2022 20:27:20 -0800 (PST), Rich S
richsulinengineer@gmail.com> wrote:

Those loadpull charts on page 5 are a mess,
unreadable, If this is what its like, then
No wonder a lot of RF guys retire unexpectedly.

RF lives in the dark ages. We need Spice models.

Don\'t mke me laugh so hard. Spice IS the dark ages.
What we need is AWR or ADS design kits.

Gerhard

What\'s wrong with knowing all the voltages and currents as a function
of time?

If you know that, you know all the RF stuff. That doesn\'t work in
reverse.

And what\'s wrong with knowing drain current as a function of gate
voltage? RF data sheets usually say \"turn the trimpot until the RF
comes out.\"

I wonder how people generate those \"design kits\" if they don\'t know
the basic electrical properties of the part. Maybe it\'s like \"load
pull\" engineering.


They probably make about eight of them over the lifetime of the part, so
statistics are hard to come by.

Cheers

Phil Hobbs

Rf is a strange world. I think its traditions pre-date computers, so
they emphasize analytical, necessarily linear, ideas like s-params and
Smith charts. Things that could be sort-of handled with pencils and
slide rules.

That\'s because non-linearities are avoided like the plague.
They cause harmonics that screw you /and other/ users up.
There are lots of /enforceable/ regulations to prevent that,
with an associated squad of men in black suits.

 

[server]

On Thu, 3 Mar 2022 17:10:41 +0000, Tom Gardner
<spamjunk@blueyonder.co.uk> wrote:

On 03/03/22 16:25, jlarkin@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 11:12:30 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 06:32:58 +0100, Gerhard Hoffmann <dk4xp@arcor.de
wrote:

Am 03.03.22 um 05:54 schrieb jlarkin@highlandsniptechnology.com:
On Wed, 2 Mar 2022 20:27:20 -0800 (PST), Rich S
richsulinengineer@gmail.com> wrote:

Those loadpull charts on page 5 are a mess,
unreadable, If this is what its like, then
No wonder a lot of RF guys retire unexpectedly.

RF lives in the dark ages. We need Spice models.

Don\'t mke me laugh so hard. Spice IS the dark ages.
What we need is AWR or ADS design kits.

Gerhard

What\'s wrong with knowing all the voltages and currents as a function
of time?

If you know that, you know all the RF stuff. That doesn\'t work in
reverse.

And what\'s wrong with knowing drain current as a function of gate
voltage? RF data sheets usually say \"turn the trimpot until the RF
comes out.\"

I wonder how people generate those \"design kits\" if they don\'t know
the basic electrical properties of the part. Maybe it\'s like \"load
pull\" engineering.


They probably make about eight of them over the lifetime of the part, so
statistics are hard to come by.

Cheers

Phil Hobbs

Rf is a strange world. I think its traditions pre-date computers, so
they emphasize analytical, necessarily linear, ideas like s-params and
Smith charts. Things that could be sort-of handled with pencils and
slide rules.

That\'s because non-linearities are avoided like the plague.
They cause harmonics that screw you /and other/ users up.

So wouldn\'t you want a Spice model to evaluate that? Not all parts are
used small-signal.

There are lots of /enforceable/ regulations to prevent that,
with an associated squad of men in black suits.

--

I yam what I yam - Popeye

 

[Phil Hobbs]

jlarkin@highlandsniptechnology.com wrote:

On Thu, 3 Mar 2022 17:10:41 +0000, Tom Gardner
spamjunk@blueyonder.co.uk> wrote:

On 03/03/22 16:25, jlarkin@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 11:12:30 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 06:32:58 +0100, Gerhard Hoffmann <dk4xp@arcor.de
wrote:

Am 03.03.22 um 05:54 schrieb jlarkin@highlandsniptechnology.com:
On Wed, 2 Mar 2022 20:27:20 -0800 (PST), Rich S
richsulinengineer@gmail.com> wrote:

Those loadpull charts on page 5 are a mess,
unreadable, If this is what its like, then
No wonder a lot of RF guys retire unexpectedly.

RF lives in the dark ages. We need Spice models.

Don\'t mke me laugh so hard. Spice IS the dark ages.
What we need is AWR or ADS design kits.

Gerhard

What\'s wrong with knowing all the voltages and currents as a function
of time?

If you know that, you know all the RF stuff. That doesn\'t work in
reverse.

And what\'s wrong with knowing drain current as a function of gate
voltage? RF data sheets usually say \"turn the trimpot until the RF
comes out.\"

I wonder how people generate those \"design kits\" if they don\'t know
the basic electrical properties of the part. Maybe it\'s like \"load
pull\" engineering.


They probably make about eight of them over the lifetime of the part, so
statistics are hard to come by.

Cheers

Phil Hobbs

Rf is a strange world. I think its traditions pre-date computers, so
they emphasize analytical, necessarily linear, ideas like s-params and
Smith charts. Things that could be sort-of handled with pencils and
slide rules.

That\'s because non-linearities are avoided like the plague.
They cause harmonics that screw you /and other/ users up.

So wouldn\'t you want a Spice model to evaluate that? Not all parts are
used small-signal.

There are lots of /enforceable/ regulations to prevent that,
with an associated squad of men in black suits.

The part is specified at its *3 dB* compression point. Pretty hard to
avoid lotsa distortion there!

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[John Larkin]

On Thu, 3 Mar 2022 12:20:12 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 17:10:41 +0000, Tom Gardner
spamjunk@blueyonder.co.uk> wrote:

On 03/03/22 16:25, jlarkin@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 11:12:30 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 06:32:58 +0100, Gerhard Hoffmann <dk4xp@arcor.de
wrote:

Am 03.03.22 um 05:54 schrieb jlarkin@highlandsniptechnology.com:
On Wed, 2 Mar 2022 20:27:20 -0800 (PST), Rich S
richsulinengineer@gmail.com> wrote:

Those loadpull charts on page 5 are a mess,
unreadable, If this is what its like, then
No wonder a lot of RF guys retire unexpectedly.

RF lives in the dark ages. We need Spice models.

Don\'t mke me laugh so hard. Spice IS the dark ages.
What we need is AWR or ADS design kits.

Gerhard

What\'s wrong with knowing all the voltages and currents as a function
of time?

If you know that, you know all the RF stuff. That doesn\'t work in
reverse.

And what\'s wrong with knowing drain current as a function of gate
voltage? RF data sheets usually say \"turn the trimpot until the RF
comes out.\"

I wonder how people generate those \"design kits\" if they don\'t know
the basic electrical properties of the part. Maybe it\'s like \"load
pull\" engineering.


They probably make about eight of them over the lifetime of the part, so
statistics are hard to come by.

Cheers

Phil Hobbs

Rf is a strange world. I think its traditions pre-date computers, so
they emphasize analytical, necessarily linear, ideas like s-params and
Smith charts. Things that could be sort-of handled with pencils and
slide rules.

That\'s because non-linearities are avoided like the plague.
They cause harmonics that screw you /and other/ users up.

So wouldn\'t you want a Spice model to evaluate that? Not all parts are
used small-signal.

There are lots of /enforceable/ regulations to prevent that,
with an associated squad of men in black suits.

The part is specified at its *3 dB* compression point. Pretty hard to
avoid lotsa distortion there!

Cheers

Phil Hobbs

It must be hard to simulate frequency-hopping complex-constellation
multiple-antenna RF systems. That\'s probably the big use for
million-dollar oscilloscopes.

--

If a man will begin with certainties, he shall end with doubts,
but if he will be content to begin with doubts he shall end in certainties.
Francis Bacon

 

[Joe Gwinn]

On Thu, 3 Mar 2022 12:20:12 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 17:10:41 +0000, Tom Gardner
spamjunk@blueyonder.co.uk> wrote:

On 03/03/22 16:25, jlarkin@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 11:12:30 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 06:32:58 +0100, Gerhard Hoffmann <dk4xp@arcor.de
wrote:

Am 03.03.22 um 05:54 schrieb jlarkin@highlandsniptechnology.com:
On Wed, 2 Mar 2022 20:27:20 -0800 (PST), Rich S
richsulinengineer@gmail.com> wrote:

Those loadpull charts on page 5 are a mess,
unreadable, If this is what its like, then
No wonder a lot of RF guys retire unexpectedly.

RF lives in the dark ages. We need Spice models.

Don\'t mke me laugh so hard. Spice IS the dark ages.
What we need is AWR or ADS design kits.

Gerhard

What\'s wrong with knowing all the voltages and currents as a function
of time?

If you know that, you know all the RF stuff. That doesn\'t work in
reverse.

And what\'s wrong with knowing drain current as a function of gate
voltage? RF data sheets usually say \"turn the trimpot until the RF
comes out.\"

I wonder how people generate those \"design kits\" if they don\'t know
the basic electrical properties of the part. Maybe it\'s like \"load
pull\" engineering.


They probably make about eight of them over the lifetime of the part, so
statistics are hard to come by.

Cheers

Phil Hobbs

Rf is a strange world. I think its traditions pre-date computers, so
they emphasize analytical, necessarily linear, ideas like s-params and
Smith charts. Things that could be sort-of handled with pencils and
slide rules.

Yes. Well before computers. And the key was finding the right
mathematical and physical approximations, yielding an analytically
tractable theory that was also useful.

That\'s because non-linearities are avoided like the plague.
They cause harmonics that screw you /and other/ users up.

So wouldn\'t you want a Spice model to evaluate that? Not all parts are
used small-signal.

Well, the device manufacturers do have such models, but the
manufacturers do not release anything that revealing, to avoid
educating their competitors.

There are lots of /enforceable/ regulations to prevent that,
with an associated squad of men in black suits.

Yes. NTIA.

The part is specified at its *3 dB* compression point. Pretty hard to
avoid lotsa distortion there!

Yeah, but DC to RF efficiency is higher, which is OK is one can afford
a bigger output filtering system.

Often, intermediate driver amps (which drive the final amp) are 3db,
but the final amps (which drives the antenna) are 1 dB.


Joe Gwinn

 

[John Larkin]

On Thu, 03 Mar 2022 15:52:13 -0500, Joe Gwinn <joegwinn@comcast.net>
wrote:

On Thu, 3 Mar 2022 12:20:12 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 17:10:41 +0000, Tom Gardner
spamjunk@blueyonder.co.uk> wrote:

On 03/03/22 16:25, jlarkin@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 11:12:30 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 06:32:58 +0100, Gerhard Hoffmann <dk4xp@arcor.de
wrote:

Am 03.03.22 um 05:54 schrieb jlarkin@highlandsniptechnology.com:
On Wed, 2 Mar 2022 20:27:20 -0800 (PST), Rich S
richsulinengineer@gmail.com> wrote:

Those loadpull charts on page 5 are a mess,
unreadable, If this is what its like, then
No wonder a lot of RF guys retire unexpectedly.

RF lives in the dark ages. We need Spice models.

Don\'t mke me laugh so hard. Spice IS the dark ages.
What we need is AWR or ADS design kits.

Gerhard

What\'s wrong with knowing all the voltages and currents as a function
of time?

If you know that, you know all the RF stuff. That doesn\'t work in
reverse.

And what\'s wrong with knowing drain current as a function of gate
voltage? RF data sheets usually say \"turn the trimpot until the RF
comes out.\"

I wonder how people generate those \"design kits\" if they don\'t know
the basic electrical properties of the part. Maybe it\'s like \"load
pull\" engineering.


They probably make about eight of them over the lifetime of the part, so
statistics are hard to come by.

Cheers

Phil Hobbs

Rf is a strange world. I think its traditions pre-date computers, so
they emphasize analytical, necessarily linear, ideas like s-params and
Smith charts. Things that could be sort-of handled with pencils and
slide rules.

Yes. Well before computers. And the key was finding the right
mathematical and physical approximations, yielding an analytically
tractable theory that was also useful.


That\'s because non-linearities are avoided like the plague.
They cause harmonics that screw you /and other/ users up.

So wouldn\'t you want a Spice model to evaluate that? Not all parts are
used small-signal.

Well, the device manufacturers do have such models, but the
manufacturers do not release anything that revealing, to avoid
educating their competitors.

A few competitors will spend big bucks to measure the enemies parts,
and they have the facilities to do it. So why should a thousand
end-users have to do the measurements themselves, or spin product revs
until it works?

I asked MiniCircuits for Spice models of their phemts. They were
adamant, agressive even, that they will NEVER have Spice models.

Their data sheets should have a giant header that shouts

FOR RF USE ONLY



--

If a man will begin with certainties, he shall end with doubts,
but if he will be content to begin with doubts he shall end in certainties.
Francis Bacon

 

[Joe Gwinn]

On Thu, 03 Mar 2022 13:13:01 -0800, John Larkin
<jlarkin@highland_atwork_technology.com> wrote:

On Thu, 03 Mar 2022 15:52:13 -0500, Joe Gwinn <joegwinn@comcast.net
wrote:

On Thu, 3 Mar 2022 12:20:12 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 17:10:41 +0000, Tom Gardner
spamjunk@blueyonder.co.uk> wrote:

On 03/03/22 16:25, jlarkin@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 11:12:30 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 06:32:58 +0100, Gerhard Hoffmann <dk4xp@arcor.de
wrote:

Am 03.03.22 um 05:54 schrieb jlarkin@highlandsniptechnology.com:
On Wed, 2 Mar 2022 20:27:20 -0800 (PST), Rich S
richsulinengineer@gmail.com> wrote:

Those loadpull charts on page 5 are a mess,
unreadable, If this is what its like, then
No wonder a lot of RF guys retire unexpectedly.

RF lives in the dark ages. We need Spice models.

Don\'t mke me laugh so hard. Spice IS the dark ages.
What we need is AWR or ADS design kits.

Gerhard

What\'s wrong with knowing all the voltages and currents as a function
of time?

If you know that, you know all the RF stuff. That doesn\'t work in
reverse.

And what\'s wrong with knowing drain current as a function of gate
voltage? RF data sheets usually say \"turn the trimpot until the RF
comes out.\"

I wonder how people generate those \"design kits\" if they don\'t know
the basic electrical properties of the part. Maybe it\'s like \"load
pull\" engineering.


They probably make about eight of them over the lifetime of the part, so
statistics are hard to come by.

Cheers

Phil Hobbs

Rf is a strange world. I think its traditions pre-date computers, so
they emphasize analytical, necessarily linear, ideas like s-params and
Smith charts. Things that could be sort-of handled with pencils and
slide rules.

Yes. Well before computers. And the key was finding the right
mathematical and physical approximations, yielding an analytically
tractable theory that was also useful.


That\'s because non-linearities are avoided like the plague.
They cause harmonics that screw you /and other/ users up.

So wouldn\'t you want a Spice model to evaluate that? Not all parts are
used small-signal.

Well, the device manufacturers do have such models, but the
manufacturers do not release anything that revealing, to avoid
educating their competitors.


A few competitors will spend big bucks to measure the enemies parts,
and they have the facilities to do it. So why should a thousand
end-users have to do the measurements themselves, or spin product revs
until it works?

I asked MiniCircuits for Spice models of their phemts. They were
adamant, agressive even, that they will NEVER have Spice models.

Yes, but they *do* have them.

Actually, much of what they make is better simulated using a full EM
field solver, which spice cannot touch.

My guess is that if they published simplified spice models, they would
get endless questions about this or that inaccuracy, so they avoid the
expense by not issuing such models.

Their data sheets should have a giant header that shouts

FOR RF USE ONLY

They do, \"MiniCircuts\", right at the top of every page.

Joe Gwinn

 

[Lasse Langwadt Christensen]

torsdag den 3. marts 2022 kl. 22.13.17 UTC+1 skrev John Larkin:

On Thu, 03 Mar 2022 15:52:13 -0500, Joe Gwinn <joeg...@comcast.net
wrote:

On Thu, 3 Mar 2022 12:20:12 -0500, Phil Hobbs
pcdhSpamM...@electrooptical.net> wrote:

jla...@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 17:10:41 +0000, Tom Gardner
spam...@blueyonder.co.uk> wrote:

On 03/03/22 16:25, jla...@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 11:12:30 -0500, Phil Hobbs
pcdhSpamM...@electrooptical.net> wrote:

jla...@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 06:32:58 +0100, Gerhard Hoffmann <dk...@arcor.de
wrote:

Am 03.03.22 um 05:54 schrieb jla...@highlandsniptechnology.com:
On Wed, 2 Mar 2022 20:27:20 -0800 (PST), Rich S
richsuli...@gmail.com> wrote:

Those loadpull charts on page 5 are a mess,
unreadable, If this is what its like, then
No wonder a lot of RF guys retire unexpectedly.

RF lives in the dark ages. We need Spice models.

Don\'t mke me laugh so hard. Spice IS the dark ages.
What we need is AWR or ADS design kits.

Gerhard

What\'s wrong with knowing all the voltages and currents as a function
of time?

If you know that, you know all the RF stuff. That doesn\'t work in
reverse.

And what\'s wrong with knowing drain current as a function of gate
voltage? RF data sheets usually say \"turn the trimpot until the RF
comes out.\"

I wonder how people generate those \"design kits\" if they don\'t know
the basic electrical properties of the part. Maybe it\'s like \"load
pull\" engineering.


They probably make about eight of them over the lifetime of the part, so
statistics are hard to come by.

Cheers

Phil Hobbs

Rf is a strange world. I think its traditions pre-date computers, so
they emphasize analytical, necessarily linear, ideas like s-params and
Smith charts. Things that could be sort-of handled with pencils and
slide rules.

Yes. Well before computers. And the key was finding the right
mathematical and physical approximations, yielding an analytically
tractable theory that was also useful.


That\'s because non-linearities are avoided like the plague.
They cause harmonics that screw you /and other/ users up.

So wouldn\'t you want a Spice model to evaluate that? Not all parts are
used small-signal.

Well, the device manufacturers do have such models, but the
manufacturers do not release anything that revealing, to avoid
educating their competitors.
A few competitors will spend big bucks to measure the enemies parts,
and they have the facilities to do it. So why should a thousand
end-users have to do the measurements themselves, or spin product revs
until it works?

I asked MiniCircuits for Spice models of their phemts. They were
adamant, agressive even, that they will NEVER have Spice models.

Their data sheets should have a giant header that shouts

FOR RF USE ONLY

would that stop you?

and isn\'t the RF use only implied with specs only covering RF?

 

[Phil Hobbs]

Joe Gwinn wrote:

On Thu, 3 Mar 2022 12:20:12 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 17:10:41 +0000, Tom Gardner
spamjunk@blueyonder.co.uk> wrote:

On 03/03/22 16:25, jlarkin@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 11:12:30 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 06:32:58 +0100, Gerhard Hoffmann <dk4xp@arcor.de
wrote:

Am 03.03.22 um 05:54 schrieb jlarkin@highlandsniptechnology.com:
On Wed, 2 Mar 2022 20:27:20 -0800 (PST), Rich S
richsulinengineer@gmail.com> wrote:

Those loadpull charts on page 5 are a mess,
unreadable, If this is what its like, then
No wonder a lot of RF guys retire unexpectedly.

RF lives in the dark ages. We need Spice models.

Don\'t mke me laugh so hard. Spice IS the dark ages.
What we need is AWR or ADS design kits.

Gerhard

What\'s wrong with knowing all the voltages and currents as a function
of time?

If you know that, you know all the RF stuff. That doesn\'t work in
reverse.

And what\'s wrong with knowing drain current as a function of gate
voltage? RF data sheets usually say \"turn the trimpot until the RF
comes out.\"

I wonder how people generate those \"design kits\" if they don\'t know
the basic electrical properties of the part. Maybe it\'s like \"load
pull\" engineering.


They probably make about eight of them over the lifetime of the part, so
statistics are hard to come by.

Cheers

Phil Hobbs

Rf is a strange world. I think its traditions pre-date computers, so
they emphasize analytical, necessarily linear, ideas like s-params and
Smith charts. Things that could be sort-of handled with pencils and
slide rules.

Yes. Well before computers. And the key was finding the right
mathematical and physical approximations, yielding an analytically
tractable theory that was also useful.


That\'s because non-linearities are avoided like the plague.
They cause harmonics that screw you /and other/ users up.

So wouldn\'t you want a Spice model to evaluate that? Not all parts are
used small-signal.

Well, the device manufacturers do have such models, but the
manufacturers do not release anything that revealing, to avoid
educating their competitors.


There are lots of /enforceable/ regulations to prevent that,
with an associated squad of men in black suits.

Yes. NTIA.


The part is specified at its *3 dB* compression point. Pretty hard to
avoid lotsa distortion there!

Yeah, but DC to RF efficiency is higher, which is OK is one can afford
a bigger output filtering system.

Often, intermediate driver amps (which drive the final amp) are 3db,
but the final amps (which drives the antenna) are 1 dB.

The point being that TG was talking out of his, um, lower back.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Phil Hobbs]

Joe Gwinn wrote:

On Thu, 03 Mar 2022 13:13:01 -0800, John Larkin
jlarkin@highland_atwork_technology.com> wrote:

On Thu, 03 Mar 2022 15:52:13 -0500, Joe Gwinn <joegwinn@comcast.net
wrote:

On Thu, 3 Mar 2022 12:20:12 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 17:10:41 +0000, Tom Gardner
spamjunk@blueyonder.co.uk> wrote:

On 03/03/22 16:25, jlarkin@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 11:12:30 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 06:32:58 +0100, Gerhard Hoffmann <dk4xp@arcor.de
wrote:

Am 03.03.22 um 05:54 schrieb jlarkin@highlandsniptechnology.com:
On Wed, 2 Mar 2022 20:27:20 -0800 (PST), Rich S
richsulinengineer@gmail.com> wrote:

Those loadpull charts on page 5 are a mess,
unreadable, If this is what its like, then
No wonder a lot of RF guys retire unexpectedly.

RF lives in the dark ages. We need Spice models.

Don\'t mke me laugh so hard. Spice IS the dark ages.
What we need is AWR or ADS design kits.

Gerhard

What\'s wrong with knowing all the voltages and currents as a function
of time?

If you know that, you know all the RF stuff. That doesn\'t work in
reverse.

And what\'s wrong with knowing drain current as a function of gate
voltage? RF data sheets usually say \"turn the trimpot until the RF
comes out.\"

I wonder how people generate those \"design kits\" if they don\'t know
the basic electrical properties of the part. Maybe it\'s like \"load
pull\" engineering.


They probably make about eight of them over the lifetime of the part, so
statistics are hard to come by.

Cheers

Phil Hobbs

Rf is a strange world. I think its traditions pre-date computers, so
they emphasize analytical, necessarily linear, ideas like s-params and
Smith charts. Things that could be sort-of handled with pencils and
slide rules.

Yes. Well before computers. And the key was finding the right
mathematical and physical approximations, yielding an analytically
tractable theory that was also useful.


That\'s because non-linearities are avoided like the plague.
They cause harmonics that screw you /and other/ users up.

So wouldn\'t you want a Spice model to evaluate that? Not all parts are
used small-signal.

Well, the device manufacturers do have such models, but the
manufacturers do not release anything that revealing, to avoid
educating their competitors.


A few competitors will spend big bucks to measure the enemies parts,
and they have the facilities to do it. So why should a thousand
end-users have to do the measurements themselves, or spin product revs
until it works?

I asked MiniCircuits for Spice models of their phemts. They were
adamant, agressive even, that they will NEVER have Spice models.

Yes, but they *do* have them.

You know this how, exactly?

Actually, much of what they make is better simulated using a full EM
field solver, which spice cannot touch.

SPICE is a pretty capable package for solving sparse systems of
nonlinear ODEs, with a few features bolted on for other things such as
transmission lines. (A transmission line has invisible internal state,
and so can\'t be simulated by ODEs.)

It doesn\'t model carrier diffusion, which is probably its worst
deficiency in high speed circuitry. Second worst is that its noise
simulation capability is very limited--it\'s just a linearized
propagation-of-errors calculation based on a single operating point. In
reality, many noise sources don\'t behave that way--for instance, shot
noise depends on the instantaneous current, so noise correlations with
signal can be far from negligible in real life.

But most of those things aren\'t done any better by your average
full-wave EM code, which has zero information about the circuit
properties and probably couldn\'t do carrier dynamics to save its virtual
life, even if you gave it a physical description of the circuit with the
required spatial resolution everywhere. (This would not be your elegant
lightweight input file, you understand.)

I wrote a clusterized optimizing FDTD code for my antenna-coupled MIM
tunnel junction work about 15 years ago, so I have relevant experience.

My guess is that if they published simplified spice models, they would
get endless questions about this or that inaccuracy, so they avoid the
expense by not issuing such models.

Op amp makers have the inaccuracy problem in spades, which they handle
by lying through their teeth AFAICT--they say that better models would
reveal too much about their designs, or run too slowly, or put warts on
everybody\'s nose, or something.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[John Larkin]

On Thu, 03 Mar 2022 17:08:32 -0500, Joe Gwinn <joegwinn@comcast.net>
wrote:

On Thu, 03 Mar 2022 13:13:01 -0800, John Larkin
jlarkin@highland_atwork_technology.com> wrote:

On Thu, 03 Mar 2022 15:52:13 -0500, Joe Gwinn <joegwinn@comcast.net
wrote:

On Thu, 3 Mar 2022 12:20:12 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 17:10:41 +0000, Tom Gardner
spamjunk@blueyonder.co.uk> wrote:

On 03/03/22 16:25, jlarkin@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 11:12:30 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 06:32:58 +0100, Gerhard Hoffmann <dk4xp@arcor.de
wrote:

Am 03.03.22 um 05:54 schrieb jlarkin@highlandsniptechnology.com:
On Wed, 2 Mar 2022 20:27:20 -0800 (PST), Rich S
richsulinengineer@gmail.com> wrote:

Those loadpull charts on page 5 are a mess,
unreadable, If this is what its like, then
No wonder a lot of RF guys retire unexpectedly.

RF lives in the dark ages. We need Spice models.

Don\'t mke me laugh so hard. Spice IS the dark ages.
What we need is AWR or ADS design kits.

Gerhard

What\'s wrong with knowing all the voltages and currents as a function
of time?

If you know that, you know all the RF stuff. That doesn\'t work in
reverse.

And what\'s wrong with knowing drain current as a function of gate
voltage? RF data sheets usually say \"turn the trimpot until the RF
comes out.\"

I wonder how people generate those \"design kits\" if they don\'t know
the basic electrical properties of the part. Maybe it\'s like \"load
pull\" engineering.


They probably make about eight of them over the lifetime of the part, so
statistics are hard to come by.

Cheers

Phil Hobbs

Rf is a strange world. I think its traditions pre-date computers, so
they emphasize analytical, necessarily linear, ideas like s-params and
Smith charts. Things that could be sort-of handled with pencils and
slide rules.

Yes. Well before computers. And the key was finding the right
mathematical and physical approximations, yielding an analytically
tractable theory that was also useful.


That\'s because non-linearities are avoided like the plague.
They cause harmonics that screw you /and other/ users up.

So wouldn\'t you want a Spice model to evaluate that? Not all parts are
used small-signal.

Well, the device manufacturers do have such models, but the
manufacturers do not release anything that revealing, to avoid
educating their competitors.


A few competitors will spend big bucks to measure the enemies parts,
and they have the facilities to do it. So why should a thousand
end-users have to do the measurements themselves, or spin product revs
until it works?

I asked MiniCircuits for Spice models of their phemts. They were
adamant, agressive even, that they will NEVER have Spice models.

Yes, but they *do* have them.

Then they lied to me more than once.

Actually, much of what they make is better simulated using a full EM
field solver, which spice cannot touch.

Field solver for a phemt?

My guess is that if they published simplified spice models, they would
get endless questions about this or that inaccuracy, so they avoid the
expense by not issuing such models.

Best avoid s-params too.

Their data sheets should have a giant header that shouts

FOR RF USE ONLY

They do, \"MiniCircuts\", right at the top of every page.

Joe Gwinn

Is that what \"minicircuits\" means? RF only?

I made a nice wideband step attenuator with a SAV-541. It\'s not
obvious from the data sheet that this would work. I started with
Phil\'s spice model for the SAV-551.

--

If a man will begin with certainties, he shall end with doubts,
but if he will be content to begin with doubts he shall end in certainties.
Francis Bacon

 

[John Larkin]

On Thu, 3 Mar 2022 14:12:20 -0800 (PST), Lasse Langwadt Christensen
<langwadt@fonz.dk> wrote:

torsdag den 3. marts 2022 kl. 22.13.17 UTC+1 skrev John Larkin:
On Thu, 03 Mar 2022 15:52:13 -0500, Joe Gwinn <joeg...@comcast.net
wrote:

On Thu, 3 Mar 2022 12:20:12 -0500, Phil Hobbs
pcdhSpamM...@electrooptical.net> wrote:

jla...@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 17:10:41 +0000, Tom Gardner
spam...@blueyonder.co.uk> wrote:

On 03/03/22 16:25, jla...@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 11:12:30 -0500, Phil Hobbs
pcdhSpamM...@electrooptical.net> wrote:

jla...@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 06:32:58 +0100, Gerhard Hoffmann <dk...@arcor.de
wrote:

Am 03.03.22 um 05:54 schrieb jla...@highlandsniptechnology.com:
On Wed, 2 Mar 2022 20:27:20 -0800 (PST), Rich S
richsuli...@gmail.com> wrote:

Those loadpull charts on page 5 are a mess,
unreadable, If this is what its like, then
No wonder a lot of RF guys retire unexpectedly.

RF lives in the dark ages. We need Spice models.

Don\'t mke me laugh so hard. Spice IS the dark ages.
What we need is AWR or ADS design kits.

Gerhard

What\'s wrong with knowing all the voltages and currents as a function
of time?

If you know that, you know all the RF stuff. That doesn\'t work in
reverse.

And what\'s wrong with knowing drain current as a function of gate
voltage? RF data sheets usually say \"turn the trimpot until the RF
comes out.\"

I wonder how people generate those \"design kits\" if they don\'t know
the basic electrical properties of the part. Maybe it\'s like \"load
pull\" engineering.


They probably make about eight of them over the lifetime of the part, so
statistics are hard to come by.

Cheers

Phil Hobbs

Rf is a strange world. I think its traditions pre-date computers, so
they emphasize analytical, necessarily linear, ideas like s-params and
Smith charts. Things that could be sort-of handled with pencils and
slide rules.

Yes. Well before computers. And the key was finding the right
mathematical and physical approximations, yielding an analytically
tractable theory that was also useful.


That\'s because non-linearities are avoided like the plague.
They cause harmonics that screw you /and other/ users up.

So wouldn\'t you want a Spice model to evaluate that? Not all parts are
used small-signal.

Well, the device manufacturers do have such models, but the
manufacturers do not release anything that revealing, to avoid
educating their competitors.
A few competitors will spend big bucks to measure the enemies parts,
and they have the facilities to do it. So why should a thousand
end-users have to do the measurements themselves, or spin product revs
until it works?

I asked MiniCircuits for Spice models of their phemts. They were
adamant, agressive even, that they will NEVER have Spice models.

Their data sheets should have a giant header that shouts

FOR RF USE ONLY

would that stop you?

Of course not. We use RF parts in pulse applications all the time.

>and isn\'t the RF use only implied with specs only covering RF?

Yes. They can afford to blow off us time-domain buyers.

Actually, the SAV-5xx data sheets have DC drain curves! That\'s way
more than most RF parts reveal.

We measured a lot more.

--

If a man will begin with certainties, he shall end with doubts,
but if he will be content to begin with doubts he shall end in certainties.
Francis Bacon

 

[Gerhard Hoffmann]

Am 03.03.22 um 16:21 schrieb jlarkin@highlandsniptechnology.com:

On Thu, 3 Mar 2022 06:32:58 +0100, Gerhard Hoffmann <dk4xp@arcor.de
wrote:

Am 03.03.22 um 05:54 schrieb jlarkin@highlandsniptechnology.com:
On Wed, 2 Mar 2022 20:27:20 -0800 (PST), Rich S
richsulinengineer@gmail.com> wrote:

Those loadpull charts on page 5 are a mess,
unreadable, If this is what its like, then
No wonder a lot of RF guys retire unexpectedly.

RF lives in the dark ages. We need Spice models.

Don\'t mke me laugh so hard. Spice IS the dark ages.
What we need is AWR or ADS design kits.

Gerhard

What\'s wrong with knowing all the voltages and currents as a function
of time?

We talked about pin diode switches last week. Do you know
the carrier lifetime of the diodes? Does Spice have any
idea what that might be? And this is THE parameter that
makes PIN diodes happen.

And the voltage exactly when/where on a polysilicon gate.
End, feed point, somewhere in between?

If you know that, you know all the RF stuff. That doesn\'t work in
reverse.

What with noise calculations in a nonlinear environment?
Try that with Spice in a chopper amplifier.

Which operating point would you choose in the chopper
amplifier? Switch at A or B? You must make up your mind;
noise analysis has not the concept of time.

It takes harmonic balance methods to do it.

Spice is NOT a large-signal simulator. What you get is
small signal behavior around approximated operating points
that shift around as crazy as a function of time.

Transient analysis is wrapped around the small signal linear
analysis as just another layer.

And what\'s wrong with knowing drain current as a function of gate
voltage? RF data sheets usually say \"turn the trimpot until the RF
comes out.\"

I wonder how people generate those \"design kits\" if they don\'t know
the basic electrical properties of the part. Maybe it\'s like \"load
pull\" engineering.

Ask THEM for example:
< https://www.minicircuits.com/applications/Modelithics.html >

X-parameters are like s-parameters, only large signal.

<
https://www.modelithics.com/FreeDownloads/Brochures/Modelithics_GaN_Modeling_1705.pdf
>

You also get ADS design kits fom NXP, or Infineon etc.
<
https://www.nxp.com/products/radio-frequency/rf-high-power-models/models-for-ads-keysight-advanced-design-system:RF_HIGH_POWER_MODELS_KEYSIGHT
>

cheers, Gerhard

 

[Jan Panteltje]

On a sunny day (Thu, 03 Mar 2022 13:13:01 -0800) it happened John Larkin
<jlarkin@highland_atwork_technology.com> wrote in
<sgb22hp17vp6tad22b0e900asqnpjikmqt@4ax.com>:

Their data sheets should have a giant header that shouts

FOR RF USE ONLY

John, that is their market.
If you want to use your bike for mountain climbing you cannot demand all bike manufacturers to give specs for that.
It is NOT that hard to make a test circuit and measure things, I do that with most new to me devices
including Minicircuits (you actually gave me the idea to try some of their stuff (mixers)..)
If it works it works, I have done spice simulation that told me things did not work that I used for many years
without problems...
Spice may be nice for complex filters etc, but there are better programs for that
the rest really needs just hands on experience and UNDERSTANDING about how them electrons like to move.
And the time factor, test maybe be an afternoon and even bending a PCB trace makes lot of difference,
spice you can do for weeks, have then nothing you can be sure about that works
Imagine WW3 and you only have a hand full of BC547 or something that survived the EMP and now you need to build that radio
No spice bummer...
No problem for me.

 

[server]

On Fri, 04 Mar 2022 08:41:25 GMT, Jan Panteltje
<pNaonStpealmtje@yahoo.com> wrote:

On a sunny day (Thu, 03 Mar 2022 13:13:01 -0800) it happened John Larkin
jlarkin@highland_atwork_technology.com> wrote in
sgb22hp17vp6tad22b0e900asqnpjikmqt@4ax.com>:

Their data sheets should have a giant header that shouts

FOR RF USE ONLY

John, that is their market.

They have defined it as such, so deliberately discouraged a large
class of potential customers. That\'s weird.

If you want to use your bike for mountain climbing you cannot demand all bike manufacturers to give specs for that.
It is NOT that hard to make a test circuit and measure things, I do that with most new to me devices
including Minicircuits (you actually gave me the idea to try some of their stuff (mixers)..)

We do measure things. And have to generate our own Spice models. In
the case of this new fet, it\'s arguably a depletion fet and there is
no Idss specified. They basicaly say, bias it until it works.

That\'s crazy.

If it works it works, I have done spice simulation that told me things did not work that I used for many years
without problems...
Spice may be nice for complex filters etc, but there are better programs for that
the rest really needs just hands on experience and UNDERSTANDING about how them electrons like to move.
And the time factor, test maybe be an afternoon and even bending a PCB trace makes lot of difference,
spice you can do for weeks, have then nothing you can be sure about that works
Imagine WW3 and you only have a hand full of BC547 or something that survived the EMP and now you need to build that radio
No spice bummer...
No problem for me.

Just more work for everyone.

They probably support people who will buy millions.



--

I yam what I yam - Popeye

 

[server]

On Thu, 3 Mar 2022 17:43:15 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

Joe Gwinn wrote:
On Thu, 03 Mar 2022 13:13:01 -0800, John Larkin
jlarkin@highland_atwork_technology.com> wrote:

On Thu, 03 Mar 2022 15:52:13 -0500, Joe Gwinn <joegwinn@comcast.net
wrote:

On Thu, 3 Mar 2022 12:20:12 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 17:10:41 +0000, Tom Gardner
spamjunk@blueyonder.co.uk> wrote:

On 03/03/22 16:25, jlarkin@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 11:12:30 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Thu, 3 Mar 2022 06:32:58 +0100, Gerhard Hoffmann <dk4xp@arcor.de
wrote:

Am 03.03.22 um 05:54 schrieb jlarkin@highlandsniptechnology.com:
On Wed, 2 Mar 2022 20:27:20 -0800 (PST), Rich S
richsulinengineer@gmail.com> wrote:

Those loadpull charts on page 5 are a mess,
unreadable, If this is what its like, then
No wonder a lot of RF guys retire unexpectedly.

RF lives in the dark ages. We need Spice models.

Don\'t mke me laugh so hard. Spice IS the dark ages.
What we need is AWR or ADS design kits.

Gerhard

What\'s wrong with knowing all the voltages and currents as a function
of time?

If you know that, you know all the RF stuff. That doesn\'t work in
reverse.

And what\'s wrong with knowing drain current as a function of gate
voltage? RF data sheets usually say \"turn the trimpot until the RF
comes out.\"

I wonder how people generate those \"design kits\" if they don\'t know
the basic electrical properties of the part. Maybe it\'s like \"load
pull\" engineering.


They probably make about eight of them over the lifetime of the part, so
statistics are hard to come by.

Cheers

Phil Hobbs

Rf is a strange world. I think its traditions pre-date computers, so
they emphasize analytical, necessarily linear, ideas like s-params and
Smith charts. Things that could be sort-of handled with pencils and
slide rules.

Yes. Well before computers. And the key was finding the right
mathematical and physical approximations, yielding an analytically
tractable theory that was also useful.


That\'s because non-linearities are avoided like the plague.
They cause harmonics that screw you /and other/ users up.

So wouldn\'t you want a Spice model to evaluate that? Not all parts are
used small-signal.

Well, the device manufacturers do have such models, but the
manufacturers do not release anything that revealing, to avoid
educating their competitors.


A few competitors will spend big bucks to measure the enemies parts,
and they have the facilities to do it. So why should a thousand
end-users have to do the measurements themselves, or spin product revs
until it works?

I asked MiniCircuits for Spice models of their phemts. They were
adamant, agressive even, that they will NEVER have Spice models.

Yes, but they *do* have them.

You know this how, exactly?

Actually, much of what they make is better simulated using a full EM
field solver, which spice cannot touch.

SPICE is a pretty capable package for solving sparse systems of
nonlinear ODEs, with a few features bolted on for other things such as
transmission lines. (A transmission line has invisible internal state,
and so can\'t be simulated by ODEs.)

It doesn\'t model carrier diffusion, which is probably its worst
deficiency in high speed circuitry. Second worst is that its noise
simulation capability is very limited--it\'s just a linearized
propagation-of-errors calculation based on a single operating point. In
reality, many noise sources don\'t behave that way--for instance, shot
noise depends on the instantaneous current, so noise correlations with
signal can be far from negligible in real life.

But most of those things aren\'t done any better by your average
full-wave EM code, which has zero information about the circuit
properties and probably couldn\'t do carrier dynamics to save its virtual
life, even if you gave it a physical description of the circuit with the
required spatial resolution everywhere. (This would not be your elegant
lightweight input file, you understand.)

I wrote a clusterized optimizing FDTD code for my antenna-coupled MIM
tunnel junction work about 15 years ago, so I have relevant experience.

My guess is that if they published simplified spice models, they would
get endless questions about this or that inaccuracy, so they avoid the
expense by not issuing such models.

Op amp makers have the inaccuracy problem in spades, which they handle
by lying through their teeth AFAICT--they say that better models would
reveal too much about their designs, or run too slowly, or put warts on
everybody\'s nose, or something.

Cheers

Phil Hobbs

We should distinguish between a \"Spice model\" and a Spice program.

This is a jfet model:

..model 2N3819 NJF(Beta=1.304m Betatce=-.5 Rd=1 Rs=1 Lambda=2.25m
Vto=-3 Vtotc=-2.5m Is=33.57f Isr=322.4f N=1 Nr=2 Xti=3 Alpha=311.7u
Vk=243.6 Cgd=1.6p M=.3622 Pb=1 Fc=.5 Cgs=2.414p Kf=9.882E-18 Af=1
mfg=Vishay)

It assigns values in SI units to elements of device physics. That,
plus some package parasitics and thermals, defines the device. That
could be the input to LT Spice or to an expensive RF suite or to 12
professors with slide rules.

But the values are there. Narrowband load pull measurements are
different.

Opamp models can be incomplete, but they are better than s-parameters.





--

I yam what I yam - Popeye

 

[Jan Panteltje]

On a sunny day (Fri, 04 Mar 2022 06:36:25 -0800) it happened
jlarkin@highlandsniptechnology.com wrote in
<nl842h59cjijh7s4op6fbvvgjlt7n54k03@4ax.com>:

On Fri, 04 Mar 2022 08:41:25 GMT, Jan Panteltje
pNaonStpealmtje@yahoo.com> wrote:

On a sunny day (Thu, 03 Mar 2022 13:13:01 -0800) it happened John Larkin
jlarkin@highland_atwork_technology.com> wrote in
sgb22hp17vp6tad22b0e900asqnpjikmqt@4ax.com>:

Their data sheets should have a giant header that shouts

FOR RF USE ONLY

John, that is their market.

They have defined it as such, so deliberately discouraged a large
class of potential customers. That\'s weird.


If you want to use your bike for mountain climbing you cannot demand all bike manufacturers to give specs for that.
It is NOT that hard to make a test circuit and measure things, I do that with most new to me devices
including Minicircuits (you actually gave me the idea to try some of their stuff (mixers)..)

We do measure things. And have to generate our own Spice models. In
the case of this new fet, it\'s arguably a depletion fet and there is
no Idss specified. They basicaly say, bias it until it works.

That\'s crazy.

Well its nature
There may be / will be some production spread in the cut-off gate voltage, that is with all FETs.
You could make a feedback loop..

If it works it works, I have done spice simulation that told me things did not work that I used for many years
without problems...
Spice may be nice for complex filters etc, but there are better programs for that
the rest really needs just hands on experience and UNDERSTANDING about how them electrons like to move.
And the time factor, test maybe be an afternoon and even bending a PCB trace makes lot of difference,
spice you can do for weeks, have then nothing you can be sure about that works
Imagine WW3 and you only have a hand full of BC547 or something that survived the EMP and now you need to build that radio
No spice bummer...
No problem for me.


Just more work for everyone.

But you need that test circuit and measurements anyway? I do.


>They probably support people who will buy millions.

And it is also the fun of learning something new
Am working at version 0.5.1 of my FLIR software, things evolve.

 

[server]

On Fri, 04 Mar 2022 15:20:45 GMT, Jan Panteltje
<pNaonStpealmtje@yahoo.com> wrote:

On a sunny day (Fri, 04 Mar 2022 06:36:25 -0800) it happened
jlarkin@highlandsniptechnology.com wrote in
nl842h59cjijh7s4op6fbvvgjlt7n54k03@4ax.com>:

On Fri, 04 Mar 2022 08:41:25 GMT, Jan Panteltje
pNaonStpealmtje@yahoo.com> wrote:

On a sunny day (Thu, 03 Mar 2022 13:13:01 -0800) it happened John Larkin
jlarkin@highland_atwork_technology.com> wrote in
sgb22hp17vp6tad22b0e900asqnpjikmqt@4ax.com>:

Their data sheets should have a giant header that shouts

FOR RF USE ONLY

John, that is their market.

They have defined it as such, so deliberately discouraged a large
class of potential customers. That\'s weird.


If you want to use your bike for mountain climbing you cannot demand all bike manufacturers to give specs for that.
It is NOT that hard to make a test circuit and measure things, I do that with most new to me devices
including Minicircuits (you actually gave me the idea to try some of their stuff (mixers)..)

We do measure things. And have to generate our own Spice models. In
the case of this new fet, it\'s arguably a depletion fet and there is
no Idss specified. They basicaly say, bias it until it works.

That\'s crazy.

Well its nature
There may be / will be some production spread in the cut-off gate voltage, that is with all FETs.
You could make a feedback loop..


If it works it works, I have done spice simulation that told me things did not work that I used for many years
without problems...
Spice may be nice for complex filters etc, but there are better programs for that
the rest really needs just hands on experience and UNDERSTANDING about how them electrons like to move.
And the time factor, test maybe be an afternoon and even bending a PCB trace makes lot of difference,
spice you can do for weeks, have then nothing you can be sure about that works
Imagine WW3 and you only have a hand full of BC547 or something that survived the EMP and now you need to build that radio
No spice bummer...
No problem for me.


Just more work for everyone.

But you need that test circuit and measurements anyway? I do.

The first step is to select a part. I don\'t want to buy and test a
hundred parts. Basic DC specs are fundamental.

They probably support people who will buy millions.

And it is also the fun of learning something new
Am working at version 0.5.1 of my FLIR software, things evolve.

--

I yam what I yam - Popeye