Baroque BJT Digital Driver Stage

[Tim Williams]

Had been meaning to finish this drawing for, hmm, guess it's about 8 years
or so. Anyway, here it is:
https://www.seventransistorlabs.com/Images/Super_Output_Stage2.png
Not too useful to me at board level, just for how many parts it takes.
Should be good for some speed and current though. (Note, resistor values
are initial guesses and subject to optimization.)

Tim

--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/

 

[John Larkin]

On Sat, 3 Aug 2019 09:41:17 -0500, "Tim Williams"
<tiwill@seventransistorlabs.com> wrote:

Had been meaning to finish this drawing for, hmm, guess it's about 8 years
or so. Anyway, here it is:
https://www.seventransistorlabs.com/Images/Super_Output_Stage2.png
Not too useful to me at board level, just for how many parts it takes.
Should be good for some speed and current though. (Note, resistor values
are initial guesses and subject to optimization.)

Tim

Time to upgrade to GaN fets!

https://www.dropbox.com/s/o3tax43t1xiivjk/T577-1A_40V.JPG?raw=1


I'm just finishing up the rev B layout. The rev A has sub-ns edges,
but there's some ringing (around 700 MHz) so I added an absorptive
output lowpass filter to beautify the pulse, but that cost me
rise/fall time. I'm optimistic that rev B will ring less, or at least
at a higher frequency.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[piglet]

On 03/08/2019 3:41 pm, Tim Williams wrote:

Had been meaning to finish this drawing for, hmm, guess it's about 8
years or so.  Anyway, here it is:
https://www.seventransistorlabs.com/Images/Super_Output_Stage2.png
Not too useful to me at board level, just for how many parts it takes.
Should be good for some speed and current though.  (Note, resistor
values are initial guesses and subject to optimization.)

Tim

Pleasingly symmetric, and exactly 7 PNP and 7 NPN.

piglet

 

[bitrex]

On 8/3/19 11:51 AM, John Larkin wrote:

On Sat, 3 Aug 2019 09:41:17 -0500, "Tim Williams"
tiwill@seventransistorlabs.com> wrote:

Had been meaning to finish this drawing for, hmm, guess it's about 8 years
or so. Anyway, here it is:
https://www.seventransistorlabs.com/Images/Super_Output_Stage2.png
Not too useful to me at board level, just for how many parts it takes.
Should be good for some speed and current though. (Note, resistor values
are initial guesses and subject to optimization.)

Tim

Time to upgrade to GaN fets!

https://www.dropbox.com/s/o3tax43t1xiivjk/T577-1A_40V.JPG?raw=1


I'm just finishing up the rev B layout. The rev A has sub-ns edges,
but there's some ringing (around 700 MHz) so I added an absorptive
output lowpass filter to beautify the pulse, but that cost me
rise/fall time. I'm optimistic that rev B will ring less, or at least
at a higher frequency.

I like the Xerox Alto-like vertical screen of that scope, is there an
advantage to using those early digital scopes in 2019? The built in
delay-lines probably make it more useful

 

[John Larkin]

On Sun, 4 Aug 2019 11:00:20 -0400, bitrex <user@example.net> wrote:

On 8/3/19 11:51 AM, John Larkin wrote:
On Sat, 3 Aug 2019 09:41:17 -0500, "Tim Williams"
tiwill@seventransistorlabs.com> wrote:

Had been meaning to finish this drawing for, hmm, guess it's about 8 years
or so. Anyway, here it is:
https://www.seventransistorlabs.com/Images/Super_Output_Stage2.png
Not too useful to me at board level, just for how many parts it takes.
Should be good for some speed and current though. (Note, resistor values
are initial guesses and subject to optimization.)

Tim

Time to upgrade to GaN fets!

https://www.dropbox.com/s/o3tax43t1xiivjk/T577-1A_40V.JPG?raw=1


I'm just finishing up the rev B layout. The rev A has sub-ns edges,
but there's some ringing (around 700 MHz) so I added an absorptive
output lowpass filter to beautify the pulse, but that cost me
rise/fall time. I'm optimistic that rev B will ring less, or at least
at a higher frequency.



I like the Xerox Alto-like vertical screen of that scope, is there an
advantage to using those early digital scopes in 2019? The built in
delay-lines probably make it more useful

The display is magnetically deflected, vertical raster scan. The video
generator is a couple square feet of TTL. There's a color version,
shadow mask tube, but I like my b+w, which is a lot sharper.

They are cheap and work very well. We have at least a dozen 1180x
scopes and maybe 50 sampling heads, up to 40 GHz, and TDR, all for
about the cost of our one 7 GHz LeCroy (which hardly anyone can
remember how to use.)

A non-sampling (realtime ADC) version of my scope might cost a
megabuck.

I rarely use the delay-line "internal" trigger. I generally use one of
our digital delay generators to manage an experiment, and give the
scope a pre-trigger. Or sometimes give the scope a delayed trigger.
Our DDGs have much less jitter for longish delays than those scopes
do.

A hobbyist or startup could get into the picosecond business with one
of these and a few other bits of gear for under $2K.

An interesting box would host a few SD-series Tek sampling heads, with
a timebase and a USB interface. Tek showed such a box once at a trade
show, but never offered it for sale.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics