The 12V level shifter saga

dagmargoodboat@yahoo.com wrote:

Over the past few years I've designed and am still actively
extending a line of pulse generators that produce kilovolt
pulses with nanosecond rise and fall times from logic-level
inputs. So I feel at least somewhat familiar with the
issues attending high-speed level translation.

I'm confident your problem could be solved with discretes.
Click to expand...

So am I. But not in a straight-forward way, I have already checked
that and the results are far worse than expected.

I know nothing about short HV pulse generation, but I am sure that you
don't make it out of a handful of BC847-s.

But what I don't know is how to do
it more simply than the single BJT booster you've already
rejected for being too complex.
Click to expand...

This rejection is a result of complexity evaluation against an
alternative working solution, which requires 1 part. The booster
is composed of 3 parts, which makes it 3x more complex than an LM5101.

Best regards, Piotr
 
On Friday, February 7, 2020 at 2:49:41 AM UTC-5, Piotr Wyderski wrote:
dagmargoodboat@yahoo.com wrote:

Over the past few years I've designed and am still actively
extending a line of pulse generators that produce kilovolt
pulses with nanosecond rise and fall times from logic-level
inputs. So I feel at least somewhat familiar with the
issues attending high-speed level translation.

I'm confident your problem could be solved with discretes.

So am I. But not in a straight-forward way, I have already checked
that and the results are far worse than expected.

I know nothing about short HV pulse generation, but I am sure that you
don't make it out of a handful of BC847-s.

But what I don't know is how to do
it more simply than the single BJT booster you've already
rejected for being too complex.
Click to expand...

This rejection is a result of complexity evaluation against an
alternative working solution, which requires 1 part. The booster
is composed of 3 parts, which makes it 3x more complex than an LM5101.

Best regards, Piotr
Click to expand...

I certainly understand that, and believe me, I feel your pain.

The LM5101 would be great, but it doesn't do d.c. (as you say
you need), and it only drives 1.6A up and 1.8A down, well shy
of your 12A goal.

It sure seems like someone /should/ have a 12A high-side driver.
But apparently (going by your reports), they don't so we've got
to do the best we can with what we've got.


Cheers,
James Arthur
 
On Thursday, February 6, 2020 at 1:58:35 PM UTC-8, Phil Hobbs wrote:
On 2020-02-06 16:16, whit3rd wrote:
On Thursday, February 6, 2020 at 11:57:55 AM UTC-8, John Larkin wrote:

But where are my diamond transistors?

The oxidation of C doesn't make a suitable insulator/passivated surface,
so it's gonna take more than a little engineering to do this.

I have no idea how far folks have got with epitaxial processing of
diamond, but "no good oxide" is no longer a cogent argument against a
semiconductor system, and hasn't been for a good many years.
Click to expand...

It's not the only argument. Diamond is metastable at ambient conditions, not
stable, and any dopant you can add might transform 'metastable' to 'unstable'.
The chemistry problem is quite complex, and most of our silicon trickery
won't transfer over. Chemical etching for V-grooves for sidewall MOSFETs?
Solders that can be used for mounting to metal? Ohmic contacts? There's a
bigger list of problems than solutions.
 
On 2020-02-07 22:39, whit3rd wrote:
On Thursday, February 6, 2020 at 1:58:35 PM UTC-8, Phil Hobbs wrote:
On 2020-02-06 16:16, whit3rd wrote:
On Thursday, February 6, 2020 at 11:57:55 AM UTC-8, John Larkin wrote:

But where are my diamond transistors?

The oxidation of C doesn't make a suitable insulator/passivated surface,
so it's gonna take more than a little engineering to do this.

I have no idea how far folks have got with epitaxial processing of
diamond, but "no good oxide" is no longer a cogent argument against a
semiconductor system, and hasn't been for a good many years.

It's not the only argument. Diamond is metastable at ambient conditions, not
stable, and any dopant you can add might transform 'metastable' to 'unstable'.
The chemistry problem is quite complex, and most of our silicon trickery
won't transfer over. Chemical etching for V-grooves for sidewall MOSFETs?
Solders that can be used for mounting to metal? Ohmic contacts? There's a
bigger list of problems than solutions.
Click to expand...

I don't claim that diamond processing is simple. Even in silicon,
relatively small departures from known conditions commonly produce
completely different results. (When I was doing my own silicon
processing to make SOI waveguides and MIM tunnel junctions, I had about
the best possible advisors but there were a lot of things I had to
discover the hard way even so.)

If you can get high-level doping, you can make ohmic contacts that way.
<https://aip.scitation.org/doi/10.1063/1.365240>

Doped diamond seems to be quite a lot more difficult to make than doped
silicon. P-type is okay
<https://aip.scitation.org/doi/10.1063/1.5111882>, but N-type presents
serious problems <https://www.pnas.org/content/116/16/7703>.

Fun.

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
 
On Sat, 8 Feb 2020 02:58:17 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-02-07 22:39, whit3rd wrote:
On Thursday, February 6, 2020 at 1:58:35 PM UTC-8, Phil Hobbs wrote:
On 2020-02-06 16:16, whit3rd wrote:
On Thursday, February 6, 2020 at 11:57:55 AM UTC-8, John Larkin wrote:

But where are my diamond transistors?

The oxidation of C doesn't make a suitable insulator/passivated surface,
so it's gonna take more than a little engineering to do this.

I have no idea how far folks have got with epitaxial processing of
diamond, but "no good oxide" is no longer a cogent argument against a
semiconductor system, and hasn't been for a good many years.

It's not the only argument. Diamond is metastable at ambient conditions, not
stable, and any dopant you can add might transform 'metastable' to 'unstable'.
The chemistry problem is quite complex, and most of our silicon trickery
won't transfer over. Chemical etching for V-grooves for sidewall MOSFETs?
Solders that can be used for mounting to metal? Ohmic contacts? There's a
bigger list of problems than solutions.

I don't claim that diamond processing is simple. Even in silicon,
relatively small departures from known conditions commonly produce
completely different results. (When I was doing my own silicon
processing to make SOI waveguides and MIM tunnel junctions, I had about
the best possible advisors but there were a lot of things I had to
discover the hard way even so.)

If you can get high-level doping, you can make ohmic contacts that way.
https://aip.scitation.org/doi/10.1063/1.365240

Doped diamond seems to be quite a lot more difficult to make than doped
silicon. P-type is okay
https://aip.scitation.org/doi/10.1063/1.5111882>, but N-type presents
serious problems <https://www.pnas.org/content/116/16/7703>.

Fun.

Cheers

Phil Hobbs
Click to expand...

That's OK. We need fast PNPs.



--

John Larkin Highland Technology, Inc

The cork popped merrily, and Lord Peter rose to his feet.
"Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"
 
dagmargoodboat@yahoo.com wrote:

The LM5101 would be great, but it doesn't do d.c. (as you say
you need), and it only drives 1.6A up and 1.8A down, well shy
of your 12A goal.
Click to expand...

LM5101 certainly can do DC, you just need to power the HB pin from an
external supply. One thing that bothers me is the integrated bootstrap
diode -- it will make the power supply rail selection unpredictable,
with possible overcurrent on the bootstrap path. But there are HB
drivers without such a diode, so it is not a big problem in practice.

Best regards, Piotr
 
I recently did a cheap solution with a cascode BJT driving a BJT current source level shifter and a tiny logic buffer bootstrapped on the high side

Cost was just 4 cents, which I considered hard to improve

Rail was 40V and had a 150ns propagation delay to high side

Low side had a bit simpler construction due to lack of bootstrapping

Cheers

Klaus
 
On Sat, 8 Feb 2020 10:53:10 -0800 (PST), Klaus Kragelund
<klauskvik@hotmail.com> wrote:

I recently did a cheap solution with a cascode BJT driving a BJT current source level shifter and a tiny logic buffer bootstrapped on the high side

Cost was just 4 cents, which I considered hard to improve

Rail was 40V and had a 150ns propagation delay to high side

Low side had a bit simpler construction due to lack of bootstrapping

Cheers

Klaus
Click to expand...

You can speed that up, to a few ns, and improve common-mode rejection
using an LVDS line receiver on the high side, single-ended like you
are probably doing but with a small receive resistor up there. Really
spiffy would be to do differential current drive up to the LVDS. But
all that would cost more.





--

John Larkin Highland Technology, Inc

The cork popped merrily, and Lord Peter rose to his feet.
"Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"
 
The LVDS driver idea is good, but a little expensive

It may also have trouble when the switch node is moving with 50V/ns

Could be fun to try it out

Cheers

Klaus
 
On Sat, 8 Feb 2020 15:38:59 -0800 (PST), klaus.kragelund@gmail.com
wrote:

The LVDS driver idea is good, but a little expensive

It may also have trouble when the switch node is moving with 50V/ns

Could be fun to try it out

Cheers

Klaus
Click to expand...

Things like this

https://www.dropbox.com/s/v23ns59k8ke1h54/LVDS_GaN_Driver.JPG?raw=1

work surprisingly well.

I have a similar thing, actually a totem pole, swinging 80 volts in
about a ns. Simple circuits that are absurdly naiive with mosfets or
bipolars often just work with GaN.



--

John Larkin Highland Technology, Inc

The cork popped merrily, and Lord Peter rose to his feet.
"Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"
 
On Sun, 9 Feb 2020 12:00:48 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-02-08 19:30, jlarkin@highlandsniptechnology.com wrote:
On Sat, 8 Feb 2020 15:38:59 -0800 (PST), klaus.kragelund@gmail.com
wrote:

The LVDS driver idea is good, but a little expensive

It may also have trouble when the switch node is moving with 50V/ns

Could be fun to try it out

Cheers

Klaus


Things like this

https://www.dropbox.com/s/v23ns59k8ke1h54/LVDS_GaN_Driver.JPG?raw=1

work surprisingly well.

I have a similar thing, actually a totem pole, swinging 80 volts in
about a ns. Simple circuits that are absurdly naiive with mosfets or
bipolars often just work with GaN.



Fun. What do you use for the 4V DC-DC?

Cheers

Phil Hobbs
Click to expand...

I usually just buy a cheap brick. The Murata has super low
capacitance.

https://www.digikey.com/product-detail/en/murata-power-solutions-inc/NXJ1S1212MC-R7/811-3096-2-ND/5697917

The windings are PCB traces and vias, and the ferrite toroid is buried
inside the PCB. Clever.

I like the Recoms and CUI bricks too. There is a common footprint for
all three.

https://www.digikey.com/product-detail/en/recom-power/R1SE-0512-H2-R/945-2273-2-ND/5226207

A couple ferrite beads on the output reduce capacitive loading even
more.



--

John Larkin Highland Technology, Inc

The cork popped merrily, and Lord Peter rose to his feet.
"Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"
 
On 2020-02-08 19:30, jlarkin@highlandsniptechnology.com wrote:
On Sat, 8 Feb 2020 15:38:59 -0800 (PST), klaus.kragelund@gmail.com
wrote:

The LVDS driver idea is good, but a little expensive

It may also have trouble when the switch node is moving with 50V/ns

Could be fun to try it out

Cheers

Klaus


Things like this

https://www.dropbox.com/s/v23ns59k8ke1h54/LVDS_GaN_Driver.JPG?raw=1

work surprisingly well.

I have a similar thing, actually a totem pole, swinging 80 volts in
about a ns. Simple circuits that are absurdly naiive with mosfets or
bipolars often just work with GaN.



Fun. What do you use for the 4V DC-DC?
Click to expand...

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
 
On 2020-02-09 12:43, jlarkin@highlandsniptechnology.com wrote:
On Sun, 9 Feb 2020 12:00:48 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-02-08 19:30, jlarkin@highlandsniptechnology.com wrote:
On Sat, 8 Feb 2020 15:38:59 -0800 (PST), klaus.kragelund@gmail.com
wrote:

The LVDS driver idea is good, but a little expensive

It may also have trouble when the switch node is moving with 50V/ns

Could be fun to try it out

Cheers

Klaus


Things like this

https://www.dropbox.com/s/v23ns59k8ke1h54/LVDS_GaN_Driver.JPG?raw=1

work surprisingly well.

I have a similar thing, actually a totem pole, swinging 80 volts in
about a ns. Simple circuits that are absurdly naiive with mosfets or
bipolars often just work with GaN.



Fun. What do you use for the 4V DC-DC?

Cheers

Phil Hobbs

I usually just buy a cheap brick. The Murata has super low
capacitance.

https://www.digikey.com/product-detail/en/murata-power-solutions-inc/NXJ1S1212MC-R7/811-3096-2-ND/5697917

The windings are PCB traces and vias, and the ferrite toroid is buried
inside the PCB. Clever.

I like the Recoms and CUI bricks too. There is a common footprint for
all three.

https://www.digikey.com/product-detail/en/recom-power/R1SE-0512-H2-R/945-2273-2-ND/5226207

A couple ferrite beads on the output reduce capacitive loading even
more.



Nice, thanks.
Click to expand...

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
 
On Sun, 9 Feb 2020 12:00:48 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-02-08 19:30, jlarkin@highlandsniptechnology.com wrote:
On Sat, 8 Feb 2020 15:38:59 -0800 (PST), klaus.kragelund@gmail.com
wrote:

The LVDS driver idea is good, but a little expensive

It may also have trouble when the switch node is moving with 50V/ns

Could be fun to try it out

Cheers

Klaus


Things like this

https://www.dropbox.com/s/v23ns59k8ke1h54/LVDS_GaN_Driver.JPG?raw=1

work surprisingly well.

I have a similar thing, actually a totem pole, swinging 80 volts in
about a ns. Simple circuits that are absurdly naiive with mosfets or
bipolars often just work with GaN.



Fun. What do you use for the 4V DC-DC?

Cheers

Phil Hobbs
Click to expand...

Here's a 50 volt pulse, 25v into 50 ohms.

https://www.dropbox.com/s/1we2lg8c6w599sk/T577_50V_LP.JPG?raw=1

This one is deliberately LC lowpass filtered to get prettier symmetric
edges.

Oh, one gotcha on those cheap unregulated dc/dc things it that they
will make outrageous voltages at no load. Add a 1K dumper or something
if you drive just CMOS gates.



--

John Larkin Highland Technology, Inc

The cork popped merrily, and Lord Peter rose to his feet.
"Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"
 
jlarkin@highlandsniptechnology.com wrote...
https://www.dropbox.com/s/v23ns59k8ke1h54/LVDS_GaN_Driver.JPG?raw=1
work surprisingly well.
Click to expand...

What low-Vgs, low Ciss parts do you like to use?


--
Thanks,
- Win
 
On 9 Feb 2020 18:10:05 -0800, Winfield Hill <winfieldhill@yahoo.com>
wrote:

jlarkin@highlandsniptechnology.com wrote...

https://www.dropbox.com/s/v23ns59k8ke1h54/LVDS_GaN_Driver.JPG?raw=1
work surprisingly well.

What low-Vgs, low Ciss parts do you like to use?
Click to expand...

The EPC bga parts. They are hard to handle, hard to rework, physically
fragile, and wonderful.

What's really low is the Crss. EPC2037 is good for 100 volts, 1.7
amps, and drain-gate capacitance is 0.1 pF. As Phil has noted,
terminal inductances are picohenries.



--

John Larkin Highland Technology, Inc

The cork popped merrily, and Lord Peter rose to his feet.
"Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"
 
On 2020-02-09 21:33, jlarkin@highlandsniptechnology.com wrote:
On 9 Feb 2020 18:10:05 -0800, Winfield Hill <winfieldhill@yahoo.com
wrote:

jlarkin@highlandsniptechnology.com wrote...

https://www.dropbox.com/s/v23ns59k8ke1h54/LVDS_GaN_Driver.JPG?raw=1
work surprisingly well.

What low-Vgs, low Ciss parts do you like to use?

The EPC bga parts. They are hard to handle, hard to rework, physically
fragile, and wonderful.

What's really low is the Crss. EPC2037 is good for 100 volts, 1.7
amps, and drain-gate capacitance is 0.1 pF. As Phil has noted,
terminal inductances are picohenries.
Click to expand...
I'll have to get a few and measure their noise. I could bootstrap a
solar panel with one of those. ;)

Have to ask Simon to do some breakouts in his abundant spare time.

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
 
On Mon, 10 Feb 2020 14:26:20 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-02-09 21:33, jlarkin@highlandsniptechnology.com wrote:
On 9 Feb 2020 18:10:05 -0800, Winfield Hill <winfieldhill@yahoo.com
wrote:

jlarkin@highlandsniptechnology.com wrote...

https://www.dropbox.com/s/v23ns59k8ke1h54/LVDS_GaN_Driver.JPG?raw=1
work surprisingly well.

What low-Vgs, low Ciss parts do you like to use?

The EPC bga parts. They are hard to handle, hard to rework, physically
fragile, and wonderful.

What's really low is the Crss. EPC2037 is good for 100 volts, 1.7
amps, and drain-gate capacitance is 0.1 pF. As Phil has noted,
terminal inductances are picohenries.



I'll have to get a few and measure their noise. I could bootstrap a
solar panel with one of those. ;)

Have to ask Simon to do some breakouts in his abundant spare time.

Cheers

Phil Hobbs
Click to expand...

We did a bunch of EPC breakouts. I could send you a few, or the
Gerbers.

https://www.dropbox.com/s/iwsfcm5jryuoxev/GaN_Boards.JPG?raw=1

It's hard to solder the BGAs to the boards. These little boards were
OK, but we are now doing better "solder mask defined pads."

I now know some things now that aren't on the data sheets.



--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
 
On 2020-02-10 16:21, John Larkin wrote:
On Mon, 10 Feb 2020 14:26:20 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-02-09 21:33, jlarkin@highlandsniptechnology.com wrote:
On 9 Feb 2020 18:10:05 -0800, Winfield Hill <winfieldhill@yahoo.com
wrote:

jlarkin@highlandsniptechnology.com wrote...

https://www.dropbox.com/s/v23ns59k8ke1h54/LVDS_GaN_Driver.JPG?raw=1
work surprisingly well.

What low-Vgs, low Ciss parts do you like to use?

The EPC bga parts. They are hard to handle, hard to rework, physically
fragile, and wonderful.

What's really low is the Crss. EPC2037 is good for 100 volts, 1.7
amps, and drain-gate capacitance is 0.1 pF. As Phil has noted,
terminal inductances are picohenries.



I'll have to get a few and measure their noise. I could bootstrap a
solar panel with one of those. ;)

Have to ask Simon to do some breakouts in his abundant spare time.

Cheers

Phil Hobbs

We did a bunch of EPC breakouts. I could send you a few, or the
Gerbers.

https://www.dropbox.com/s/iwsfcm5jryuoxev/GaN_Boards.JPG?raw=1

It's hard to solder the BGAs to the boards. These little boards were
OK, but we are now doing better "solder mask defined pads."
Click to expand...

Sort of like the SchmartBoard idea?
I now know some things now that aren't on the data sheets.
Click to expand...

Any and all of the above would be very welcome!

Thanks

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
 
On Saturday, February 8, 2020 at 7:30:19 PM UTC-5, jla...@highlandsniptechnology.com wrote:
On Sat, 8 Feb 2020 15:38:59 -0800 (PST), klaus.kragelund@gmail.com
wrote:

The LVDS driver idea is good, but a little expensive

It may also have trouble when the switch node is moving with 50V/ns

Could be fun to try it out

Cheers

Klaus


Things like this

https://www.dropbox.com/s/v23ns59k8ke1h54/LVDS_GaN_Driver.JPG?raw=1

work surprisingly well.
Click to expand...

Cute circuit. TI has some boot-strapped gate drivers that
essentially integrate that for Si MOSFETs, cap-coupled.

Cheers,
James Arthur
 
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