Discussion:
another fast one-shot
(too old to reply)
john larkin
2024-06-12 16:33:17 UTC
Permalink
Here's another idea for a fast one-shot. This is the just-apply-money
version and should get close to 1 ns pulse width and should easily
trigger at 150 MHz.

Loading Image...

I can use the other half of the dual comparator elsewhere. This one
has programmable hysteresis too.
Cursitor Doom
2024-06-12 17:22:49 UTC
Permalink
Post by john larkin
Here's another idea for a fast one-shot. This is the just-apply-money
version and should get close to 1 ns pulse width and should easily
trigger at 150 MHz.
https://www.dropbox.com/scl/fi/1okfo8964bw5m53mjmxs6/
Pecl_One_Shot_1.jpg?rlkey=dwus6qjyqsynl2rv6uje2xxtj&raw=1
Post by john larkin
I can use the other half of the dual comparator elsewhere. This one has
programmable hysteresis too.
Exposing my contemptworthy ignorance here no doubt, but what exactly is it
that is fast about this design, John? And what would its application be?
john larkin
2024-06-12 18:11:28 UTC
Permalink
On Wed, 12 Jun 2024 17:22:49 -0000 (UTC), Cursitor Doom
Post by john larkin
Post by john larkin
Here's another idea for a fast one-shot. This is the just-apply-money
version and should get close to 1 ns pulse width and should easily
trigger at 150 MHz.
https://www.dropbox.com/scl/fi/1okfo8964bw5m53mjmxs6/
Pecl_One_Shot_1.jpg?rlkey=dwus6qjyqsynl2rv6uje2xxtj&raw=1
Post by john larkin
I can use the other half of the dual comparator elsewhere. This one has
programmable hysteresis too.
Exposing my contemptworthy ignorance here no doubt, but what exactly is it
that is fast about this design, John? And what would its application be?
It would have a leading-edge prop delay of 350 ps, a minimum pulse
width just over 1 ns, and would easily trigger at 150 MHz. Integrated
one-shots, xxx123 types, are always terrible, even the obsolete ECL
ones.

It would be a programmable delay in a number of possible products,
including some optical modulators. Just playing right now.

More dollars could certainly do something faster, but as long as
customers connect boxes with cables, faster isn't worth a lot. Light
just moves too slow.

Any suggestions for a faster one-shot?
bitrex
2024-06-12 20:44:14 UTC
Permalink
Post by john larkin
On Wed, 12 Jun 2024 17:22:49 -0000 (UTC), Cursitor Doom
Post by john larkin
Post by john larkin
Here's another idea for a fast one-shot. This is the just-apply-money
version and should get close to 1 ns pulse width and should easily
trigger at 150 MHz.
https://www.dropbox.com/scl/fi/1okfo8964bw5m53mjmxs6/
Pecl_One_Shot_1.jpg?rlkey=dwus6qjyqsynl2rv6uje2xxtj&raw=1
Post by john larkin
I can use the other half of the dual comparator elsewhere. This one has
programmable hysteresis too.
Exposing my contemptworthy ignorance here no doubt, but what exactly is it
that is fast about this design, John? And what would its application be?
It would have a leading-edge prop delay of 350 ps, a minimum pulse
width just over 1 ns, and would easily trigger at 150 MHz. Integrated
one-shots, xxx123 types, are always terrible, even the obsolete ECL
ones.
It would be a programmable delay in a number of possible products,
including some optical modulators. Just playing right now.
More dollars could certainly do something faster, but as long as
customers connect boxes with cables, faster isn't worth a lot. Light
just moves too slow.
Any suggestions for a faster one-shot?
What about connecting the + of the RC to Q to speed up the discharge
john larkin
2024-06-12 21:21:13 UTC
Permalink
Post by bitrex
Post by john larkin
On Wed, 12 Jun 2024 17:22:49 -0000 (UTC), Cursitor Doom
Post by john larkin
Post by john larkin
Here's another idea for a fast one-shot. This is the just-apply-money
version and should get close to 1 ns pulse width and should easily
trigger at 150 MHz.
https://www.dropbox.com/scl/fi/1okfo8964bw5m53mjmxs6/
Pecl_One_Shot_1.jpg?rlkey=dwus6qjyqsynl2rv6uje2xxtj&raw=1
Post by john larkin
I can use the other half of the dual comparator elsewhere. This one has
programmable hysteresis too.
Exposing my contemptworthy ignorance here no doubt, but what exactly is it
that is fast about this design, John? And what would its application be?
It would have a leading-edge prop delay of 350 ps, a minimum pulse
width just over 1 ns, and would easily trigger at 150 MHz. Integrated
one-shots, xxx123 types, are always terrible, even the obsolete ECL
ones.
It would be a programmable delay in a number of possible products,
including some optical modulators. Just playing right now.
More dollars could certainly do something faster, but as long as
customers connect boxes with cables, faster isn't worth a lot. Light
just moves too slow.
Any suggestions for a faster one-shot?
What about connecting the + of the RC to Q to speed up the discharge
Pecl only swings about 0.8 volts, up close to Vcc, so it wouldn't help
much. That phemt turns on pretty hard, maybe 100 mA with Rds-on a
couple of ohms.

Speeding up the discharge would improve rep-rate but wouldn't affect
minimum pulse width. I'd need a faster comparator for that, or some
different architecture.

The phemt gate driver is a little scary but will work if done
carefully.

I could give up a bit of speed and do this in CMOS. There's a 1 ns
TinyLogic flop that's 36 cents.
Cursitor Doom
2024-06-12 22:18:43 UTC
Permalink
Post by john larkin
On Wed, 12 Jun 2024 17:22:49 -0000 (UTC), Cursitor Doom
Post by john larkin
Post by john larkin
Here's another idea for a fast one-shot. This is the just-apply-money
version and should get close to 1 ns pulse width and should easily
trigger at 150 MHz.
https://www.dropbox.com/scl/fi/1okfo8964bw5m53mjmxs6/
Pecl_One_Shot_1.jpg?rlkey=dwus6qjyqsynl2rv6uje2xxtj&raw=1
Post by john larkin
I can use the other half of the dual comparator elsewhere. This one
has programmable hysteresis too.
Exposing my contemptworthy ignorance here no doubt, but what exactly is
it that is fast about this design, John? And what would its application
be?
It would have a leading-edge prop delay of 350 ps, a minimum pulse width
just over 1 ns, and would easily trigger at 150 MHz. Integrated
one-shots, xxx123 types, are always terrible, even the obsolete ECL
ones.
It would be a programmable delay in a number of possible products,
including some optical modulators. Just playing right now.
More dollars could certainly do something faster, but as long as
customers connect boxes with cables, faster isn't worth a lot. Light
just moves too slow.
Any suggestions for a faster one-shot?
Not from me! I couldn't even design a PID controlled PLL without recourse
to the 'net.
Bill Sloman
2024-06-13 06:03:04 UTC
Permalink
Post by john larkin
On Wed, 12 Jun 2024 17:22:49 -0000 (UTC), Cursitor Doom
Post by john larkin
Post by john larkin
Here's another idea for a fast one-shot. This is the just-apply-money
version and should get close to 1 ns pulse width and should easily
trigger at 150 MHz.
https://www.dropbox.com/scl/fi/1okfo8964bw5m53mjmxs6/
Pecl_One_Shot_1.jpg?rlkey=dwus6qjyqsynl2rv6uje2xxtj&raw=1
Post by john larkin
I can use the other half of the dual comparator elsewhere. This one has
programmable hysteresis too.
Exposing my contemptworthy ignorance here no doubt, but what exactly is it
that is fast about this design, John? And what would its application be?
It would have a leading-edge prop delay of 350 ps, a minimum pulse
width just over 1 ns, and would easily trigger at 150 MHz. Integrated
one-shots, xxx123 types, are always terrible, even the obsolete ECL
ones.
It would be a programmable delay in a number of possible products,
including some optical modulators. Just playing right now.
More dollars could certainly do something faster, but as long as
customers connect boxes with cables, faster isn't worth a lot. Light
just moves too slow.
Any suggestions for a faster one-shot?
Version 4
SHEET 1 2924 1040
WIRE -592 -720 -768 -720
WIRE 128 -720 -592 -720
WIRE 304 -720 128 -720
WIRE 768 -720 304 -720
WIRE 976 -720 768 -720
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WIRE 768 -560 768 -720
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FLAG -880 496 0
FLAG 960 -320 out
SYMBOL npn 64 48 R0
SYMATTR InstName Q1
SYMATTR Value BFR92A
SYMBOL npn 704 -208 R0
SYMATTR InstName Q2
SYMATTR Value BFR92A
SYMBOL voltage -768 -80 R0
WINDOW 123 0 0 Left 0
WINDOW 39 24 44 Left 2
SYMATTR SpiceLine Rser=0.1
SYMATTR InstName V1
SYMATTR Value 5.0
SYMBOL voltage -736 624 R0
WINDOW 123 0 0 Left 0
WINDOW 39 24 44 Left 2
SYMATTR SpiceLine Rser=0.1
SYMATTR InstName V2
SYMATTR Value 4.5
SYMBOL voltage -432 224 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V3
SYMATTR Value PULSE(0 0.2 1n 300p 300p 100p 200n 2)
SYMBOL res -176 80 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R1
SYMATTR Value 22
SYMBOL res 752 480 R0
SYMATTR InstName R3
SYMATTR Value 360
SYMBOL res 112 -576 R0
SYMATTR InstName R4
SYMATTR Value 180
SYMBOL res 624 112 R0
SYMATTR InstName R5
SYMATTR Value 43
SYMBOL res 752 -576 R0
SYMATTR InstName R6
SYMATTR Value 180
SYMBOL res 288 -576 R0
SYMATTR InstName R2
SYMATTR Value 1k
SYMBOL cap 240 -304 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C1
SYMATTR Value 3.3p
SYMBOL res 288 144 R0
SYMATTR InstName R7
SYMATTR Value 1k2
SYMBOL res 496 -176 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R13
SYMATTR Value 43
SYMBOL cap -608 -384 R0
SYMATTR InstName C3
SYMATTR Value 10n
SYMBOL cap -512 640 R0
SYMATTR InstName C4
SYMATTR Value 10n
TEXT -272 1000 Left 2 !.model BFR92A NPN(IS=0.1213E-15 VAF=30 BF=94.73
IKF=0.46227 XTB=0 BR=10.729 CJC=946.47E-15 CJE=10.416E-15 TR=1.2744E-9
TF=26.796E-12 ITF=0.0044601 VTF=0.32861 XTF=0.3817 RB=14.998
RC=0.13793 RE=0.29088 Vceo=15 Icrating=4m mfg=Infineon)
TEXT -904 1024 Left 2 !.tran 0 500n 0

It's just a two transistor emitter-coupled monostable, but with the two
transistors as BFR92's run at 10mA, it produces 1nsec pulse without fuss.

Finding the broad-band PNPs to let you translate the output pulse to a
useful voltage level is tricky. Phil Hobbs has told us that there is a
least one still in production and available.
--
Bill Sloman, Sydney
--
This email has been checked for viruses by Norton antivirus software.
www.norton.com
john larkin
2024-06-13 15:31:06 UTC
Permalink
Post by Bill Sloman
Post by john larkin
On Wed, 12 Jun 2024 17:22:49 -0000 (UTC), Cursitor Doom
Post by john larkin
Post by john larkin
Here's another idea for a fast one-shot. This is the just-apply-money
version and should get close to 1 ns pulse width and should easily
trigger at 150 MHz.
https://www.dropbox.com/scl/fi/1okfo8964bw5m53mjmxs6/
Pecl_One_Shot_1.jpg?rlkey=dwus6qjyqsynl2rv6uje2xxtj&raw=1
Post by john larkin
I can use the other half of the dual comparator elsewhere. This one has
programmable hysteresis too.
Exposing my contemptworthy ignorance here no doubt, but what exactly is it
that is fast about this design, John? And what would its application be?
It would have a leading-edge prop delay of 350 ps, a minimum pulse
width just over 1 ns, and would easily trigger at 150 MHz. Integrated
one-shots, xxx123 types, are always terrible, even the obsolete ECL
ones.
It would be a programmable delay in a number of possible products,
including some optical modulators. Just playing right now.
More dollars could certainly do something faster, but as long as
customers connect boxes with cables, faster isn't worth a lot. Light
just moves too slow.
Any suggestions for a faster one-shot?
Version 4
SHEET 1 2924 1040
WIRE -592 -720 -768 -720
WIRE 128 -720 -592 -720
WIRE 304 -720 128 -720
WIRE 768 -720 304 -720
WIRE 976 -720 768 -720
WIRE 1488 -576 1488 -720
WIRE 128 -560 128 -720
WIRE 304 -560 304 -720
WIRE 768 -560 768 -720
WIRE -592 -384 -592 -720
WIRE 1072 -368 1072 -400
WIRE 768 -320 768 -480
WIRE 960 -320 768 -320
WIRE 1008 -320 960 -320
WIRE 128 -288 128 -480
WIRE 176 -288 128 -288
WIRE 576 -288 240 -288
WIRE 768 -208 768 -320
WIRE 304 -160 304 -480
WIRE 400 -160 304 -160
WIRE 576 -160 576 -288
WIRE 576 -160 480 -160
WIRE 640 -160 576 -160
WIRE 704 -160 640 -160
WIRE -768 -64 -768 -720
WIRE 128 48 128 -288
WIRE -272 96 -432 96
WIRE 64 96 -192 96
WIRE 640 128 640 -160
WIRE 304 160 304 -160
WIRE -432 240 -432 96
WIRE -768 416 -768 16
WIRE -768 416 -880 416
WIRE -736 416 -768 416
WIRE -592 416 -592 -320
WIRE -592 416 -736 416
WIRE -496 416 -592 416
WIRE -432 416 -432 320
WIRE -432 416 -496 416
WIRE 640 416 640 208
WIRE 640 416 -432 416
WIRE 1072 416 640 416
WIRE 128 464 128 144
WIRE 768 464 768 -112
WIRE 768 464 128 464
WIRE -880 496 -880 416
WIRE 768 496 768 464
WIRE -736 640 -736 416
WIRE -496 640 -496 416
WIRE -736 656 -736 640
WIRE -736 944 -736 720
WIRE -496 944 -496 704
WIRE -496 944 -736 944
WIRE 304 944 304 240
WIRE 304 944 -496 944
WIRE 768 944 768 576
WIRE 768 944 304 944
WIRE 1760 944 768 944
FLAG -880 496 0
FLAG 960 -320 out
SYMBOL npn 64 48 R0
SYMATTR InstName Q1
SYMATTR Value BFR92A
SYMBOL npn 704 -208 R0
SYMATTR InstName Q2
SYMATTR Value BFR92A
SYMBOL voltage -768 -80 R0
WINDOW 123 0 0 Left 0
WINDOW 39 24 44 Left 2
SYMATTR SpiceLine Rser=0.1
SYMATTR InstName V1
SYMATTR Value 5.0
SYMBOL voltage -736 624 R0
WINDOW 123 0 0 Left 0
WINDOW 39 24 44 Left 2
SYMATTR SpiceLine Rser=0.1
SYMATTR InstName V2
SYMATTR Value 4.5
SYMBOL voltage -432 224 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V3
SYMATTR Value PULSE(0 0.2 1n 300p 300p 100p 200n 2)
SYMBOL res -176 80 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R1
SYMATTR Value 22
SYMBOL res 752 480 R0
SYMATTR InstName R3
SYMATTR Value 360
SYMBOL res 112 -576 R0
SYMATTR InstName R4
SYMATTR Value 180
SYMBOL res 624 112 R0
SYMATTR InstName R5
SYMATTR Value 43
SYMBOL res 752 -576 R0
SYMATTR InstName R6
SYMATTR Value 180
SYMBOL res 288 -576 R0
SYMATTR InstName R2
SYMATTR Value 1k
SYMBOL cap 240 -304 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C1
SYMATTR Value 3.3p
SYMBOL res 288 144 R0
SYMATTR InstName R7
SYMATTR Value 1k2
SYMBOL res 496 -176 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R13
SYMATTR Value 43
SYMBOL cap -608 -384 R0
SYMATTR InstName C3
SYMATTR Value 10n
SYMBOL cap -512 640 R0
SYMATTR InstName C4
SYMATTR Value 10n
TEXT -272 1000 Left 2 !.model BFR92A NPN(IS=0.1213E-15 VAF=30 BF=94.73
IKF=0.46227 XTB=0 BR=10.729 CJC=946.47E-15 CJE=10.416E-15 TR=1.2744E-9
TF=26.796E-12 ITF=0.0044601 VTF=0.32861 XTF=0.3817 RB=14.998
RC=0.13793 RE=0.29088 Vceo=15 Icrating=4m mfg=Infineon)
TEXT -904 1024 Left 2 !.tran 0 500n 0
It's just a two transistor emitter-coupled monostable, but with the two
transistors as BFR92's run at 10mA, it produces 1nsec pulse without fuss.
Finding the broad-band PNPs to let you translate the output pulse to a
useful voltage level is tricky. Phil Hobbs has told us that there is a
least one still in production and available.
--
Bill Sloman, Sydney
What a mess. The output pulse width just follows the input pulse
width. Unless you change C1, in which case it oscillates.

It's ugly too. Obviously frobbed until it seems to work.
Bill Sloman
2024-06-22 03:13:44 UTC
Permalink
Post by john larkin
Post by Bill Sloman
Post by john larkin
On Wed, 12 Jun 2024 17:22:49 -0000 (UTC), Cursitor Doom
Post by john larkin
Post by john larkin
Here's another idea for a fast one-shot. This is the just-apply-money
version and should get close to 1 ns pulse width and should easily
trigger at 150 MHz.
https://www.dropbox.com/scl/fi/1okfo8964bw5m53mjmxs6/
Pecl_One_Shot_1.jpg?rlkey=dwus6qjyqsynl2rv6uje2xxtj&raw=1
Post by john larkin
I can use the other half of the dual comparator elsewhere. This one has
programmable hysteresis too.
Exposing my contemptworthy ignorance here no doubt, but what exactly is it
that is fast about this design, John? And what would its application be?
It would have a leading-edge prop delay of 350 ps, a minimum pulse
width just over 1 ns, and would easily trigger at 150 MHz. Integrated
one-shots, xxx123 types, are always terrible, even the obsolete ECL
ones.
It would be a programmable delay in a number of possible products,
including some optical modulators. Just playing right now.
More dollars could certainly do something faster, but as long as
customers connect boxes with cables, faster isn't worth a lot. Light
just moves too slow.
Any suggestions for a faster one-shot?
Version 4
SHEET 1 2924 1040
WIRE -592 -720 -768 -720
WIRE 128 -720 -592 -720
WIRE 304 -720 128 -720
WIRE 768 -720 304 -720
WIRE 976 -720 768 -720
WIRE 1488 -576 1488 -720
WIRE 128 -560 128 -720
WIRE 304 -560 304 -720
WIRE 768 -560 768 -720
WIRE -592 -384 -592 -720
WIRE 1072 -368 1072 -400
WIRE 768 -320 768 -480
WIRE 960 -320 768 -320
WIRE 1008 -320 960 -320
WIRE 128 -288 128 -480
WIRE 176 -288 128 -288
WIRE 576 -288 240 -288
WIRE 768 -208 768 -320
WIRE 304 -160 304 -480
WIRE 400 -160 304 -160
WIRE 576 -160 576 -288
WIRE 576 -160 480 -160
WIRE 640 -160 576 -160
WIRE 704 -160 640 -160
WIRE -768 -64 -768 -720
WIRE 128 48 128 -288
WIRE -272 96 -432 96
WIRE 64 96 -192 96
WIRE 640 128 640 -160
WIRE 304 160 304 -160
WIRE -432 240 -432 96
WIRE -768 416 -768 16
WIRE -768 416 -880 416
WIRE -736 416 -768 416
WIRE -592 416 -592 -320
WIRE -592 416 -736 416
WIRE -496 416 -592 416
WIRE -432 416 -432 320
WIRE -432 416 -496 416
WIRE 640 416 640 208
WIRE 640 416 -432 416
WIRE 1072 416 640 416
WIRE 128 464 128 144
WIRE 768 464 768 -112
WIRE 768 464 128 464
WIRE -880 496 -880 416
WIRE 768 496 768 464
WIRE -736 640 -736 416
WIRE -496 640 -496 416
WIRE -736 656 -736 640
WIRE -736 944 -736 720
WIRE -496 944 -496 704
WIRE -496 944 -736 944
WIRE 304 944 304 240
WIRE 304 944 -496 944
WIRE 768 944 768 576
WIRE 768 944 304 944
WIRE 1760 944 768 944
FLAG -880 496 0
FLAG 960 -320 out
SYMBOL npn 64 48 R0
SYMATTR InstName Q1
SYMATTR Value BFR92A
SYMBOL npn 704 -208 R0
SYMATTR InstName Q2
SYMATTR Value BFR92A
SYMBOL voltage -768 -80 R0
WINDOW 123 0 0 Left 0
WINDOW 39 24 44 Left 2
SYMATTR SpiceLine Rser=0.1
SYMATTR InstName V1
SYMATTR Value 5.0
SYMBOL voltage -736 624 R0
WINDOW 123 0 0 Left 0
WINDOW 39 24 44 Left 2
SYMATTR SpiceLine Rser=0.1
SYMATTR InstName V2
SYMATTR Value 4.5
SYMBOL voltage -432 224 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V3
SYMATTR Value PULSE(0 0.2 1n 300p 300p 100p 200n 2)
SYMBOL res -176 80 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R1
SYMATTR Value 22
SYMBOL res 752 480 R0
SYMATTR InstName R3
SYMATTR Value 360
SYMBOL res 112 -576 R0
SYMATTR InstName R4
SYMATTR Value 180
SYMBOL res 624 112 R0
SYMATTR InstName R5
SYMATTR Value 43
SYMBOL res 752 -576 R0
SYMATTR InstName R6
SYMATTR Value 180
SYMBOL res 288 -576 R0
SYMATTR InstName R2
SYMATTR Value 1k
SYMBOL cap 240 -304 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C1
SYMATTR Value 3.3p
SYMBOL res 288 144 R0
SYMATTR InstName R7
SYMATTR Value 1k2
SYMBOL res 496 -176 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R13
SYMATTR Value 43
SYMBOL cap -608 -384 R0
SYMATTR InstName C3
SYMATTR Value 10n
SYMBOL cap -512 640 R0
SYMATTR InstName C4
SYMATTR Value 10n
TEXT -272 1000 Left 2 !.model BFR92A NPN(IS=0.1213E-15 VAF=30 BF=94.73
IKF=0.46227 XTB=0 BR=10.729 CJC=946.47E-15 CJE=10.416E-15 TR=1.2744E-9
TF=26.796E-12 ITF=0.0044601 VTF=0.32861 XTF=0.3817 RB=14.998
RC=0.13793 RE=0.29088 Vceo=15 Icrating=4m mfg=Infineon)
TEXT -904 1024 Left 2 !.tran 0 500n 0
It's just a two transistor emitter-coupled monostable, but with the two
transistors as BFR92's run at 10mA, it produces 1nsec pulse without fuss.
Finding the broad-band PNPs to let you translate the output pulse to a
useful voltage level is tricky. Phil Hobbs has told us that there is a
least one still in production and available.
What a mess. The output pulse width just follows the input pulse
width. Unless you change C1, in which case it oscillates.
Actually, it doesn't. The input pulse has a full-width at half maximum
of 400psec, and the output pulse width is 1nsec, as intended
Post by john larkin
It's ugly too. Obviously frobbed until it seems to work.
"Ugly" - in this context - seems to mean "not invented by John Larkin".

It's obviously derived from a simulation I posted earlier, that produced
a longer output pulse from the same input. The emitter resistor has been
been made smaller to get a 10mA tail current, and the collector
resistors scaled down in the same proportion. That narrowed the output
pulse,and I tweaked C1 down to 3.3pF to get the 1nsec FWHM output.

There aren't enough components there to represent a mess, if you have
any idea what they are doing. If you don't, I supposed that you could
get it to oscillate. John hasn't posted his simulation, so we don't know
why it oscillated.
--
Bill Sloman, Sydney
--
This email has been checked for viruses by Norton antivirus software.
www.norton.com
john larkin
2024-06-22 05:20:31 UTC
Permalink
Post by Bill Sloman
Post by john larkin
Post by Bill Sloman
Post by john larkin
On Wed, 12 Jun 2024 17:22:49 -0000 (UTC), Cursitor Doom
Post by john larkin
Post by john larkin
Here's another idea for a fast one-shot. This is the just-apply-money
version and should get close to 1 ns pulse width and should easily
trigger at 150 MHz.
https://www.dropbox.com/scl/fi/1okfo8964bw5m53mjmxs6/
Pecl_One_Shot_1.jpg?rlkey=dwus6qjyqsynl2rv6uje2xxtj&raw=1
Post by john larkin
I can use the other half of the dual comparator elsewhere. This one has
programmable hysteresis too.
Exposing my contemptworthy ignorance here no doubt, but what exactly is it
that is fast about this design, John? And what would its application be?
It would have a leading-edge prop delay of 350 ps, a minimum pulse
width just over 1 ns, and would easily trigger at 150 MHz. Integrated
one-shots, xxx123 types, are always terrible, even the obsolete ECL
ones.
It would be a programmable delay in a number of possible products,
including some optical modulators. Just playing right now.
More dollars could certainly do something faster, but as long as
customers connect boxes with cables, faster isn't worth a lot. Light
just moves too slow.
Any suggestions for a faster one-shot?
Version 4
SHEET 1 2924 1040
WIRE -592 -720 -768 -720
WIRE 128 -720 -592 -720
WIRE 304 -720 128 -720
WIRE 768 -720 304 -720
WIRE 976 -720 768 -720
WIRE 1488 -576 1488 -720
WIRE 128 -560 128 -720
WIRE 304 -560 304 -720
WIRE 768 -560 768 -720
WIRE -592 -384 -592 -720
WIRE 1072 -368 1072 -400
WIRE 768 -320 768 -480
WIRE 960 -320 768 -320
WIRE 1008 -320 960 -320
WIRE 128 -288 128 -480
WIRE 176 -288 128 -288
WIRE 576 -288 240 -288
WIRE 768 -208 768 -320
WIRE 304 -160 304 -480
WIRE 400 -160 304 -160
WIRE 576 -160 576 -288
WIRE 576 -160 480 -160
WIRE 640 -160 576 -160
WIRE 704 -160 640 -160
WIRE -768 -64 -768 -720
WIRE 128 48 128 -288
WIRE -272 96 -432 96
WIRE 64 96 -192 96
WIRE 640 128 640 -160
WIRE 304 160 304 -160
WIRE -432 240 -432 96
WIRE -768 416 -768 16
WIRE -768 416 -880 416
WIRE -736 416 -768 416
WIRE -592 416 -592 -320
WIRE -592 416 -736 416
WIRE -496 416 -592 416
WIRE -432 416 -432 320
WIRE -432 416 -496 416
WIRE 640 416 640 208
WIRE 640 416 -432 416
WIRE 1072 416 640 416
WIRE 128 464 128 144
WIRE 768 464 768 -112
WIRE 768 464 128 464
WIRE -880 496 -880 416
WIRE 768 496 768 464
WIRE -736 640 -736 416
WIRE -496 640 -496 416
WIRE -736 656 -736 640
WIRE -736 944 -736 720
WIRE -496 944 -496 704
WIRE -496 944 -736 944
WIRE 304 944 304 240
WIRE 304 944 -496 944
WIRE 768 944 768 576
WIRE 768 944 304 944
WIRE 1760 944 768 944
FLAG -880 496 0
FLAG 960 -320 out
SYMBOL npn 64 48 R0
SYMATTR InstName Q1
SYMATTR Value BFR92A
SYMBOL npn 704 -208 R0
SYMATTR InstName Q2
SYMATTR Value BFR92A
SYMBOL voltage -768 -80 R0
WINDOW 123 0 0 Left 0
WINDOW 39 24 44 Left 2
SYMATTR SpiceLine Rser=0.1
SYMATTR InstName V1
SYMATTR Value 5.0
SYMBOL voltage -736 624 R0
WINDOW 123 0 0 Left 0
WINDOW 39 24 44 Left 2
SYMATTR SpiceLine Rser=0.1
SYMATTR InstName V2
SYMATTR Value 4.5
SYMBOL voltage -432 224 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V3
SYMATTR Value PULSE(0 0.2 1n 300p 300p 100p 200n 2)
SYMBOL res -176 80 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R1
SYMATTR Value 22
SYMBOL res 752 480 R0
SYMATTR InstName R3
SYMATTR Value 360
SYMBOL res 112 -576 R0
SYMATTR InstName R4
SYMATTR Value 180
SYMBOL res 624 112 R0
SYMATTR InstName R5
SYMATTR Value 43
SYMBOL res 752 -576 R0
SYMATTR InstName R6
SYMATTR Value 180
SYMBOL res 288 -576 R0
SYMATTR InstName R2
SYMATTR Value 1k
SYMBOL cap 240 -304 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C1
SYMATTR Value 3.3p
SYMBOL res 288 144 R0
SYMATTR InstName R7
SYMATTR Value 1k2
SYMBOL res 496 -176 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R13
SYMATTR Value 43
SYMBOL cap -608 -384 R0
SYMATTR InstName C3
SYMATTR Value 10n
SYMBOL cap -512 640 R0
SYMATTR InstName C4
SYMATTR Value 10n
TEXT -272 1000 Left 2 !.model BFR92A NPN(IS=0.1213E-15 VAF=30 BF=94.73
IKF=0.46227 XTB=0 BR=10.729 CJC=946.47E-15 CJE=10.416E-15 TR=1.2744E-9
TF=26.796E-12 ITF=0.0044601 VTF=0.32861 XTF=0.3817 RB=14.998
RC=0.13793 RE=0.29088 Vceo=15 Icrating=4m mfg=Infineon)
TEXT -904 1024 Left 2 !.tran 0 500n 0
It's just a two transistor emitter-coupled monostable, but with the two
transistors as BFR92's run at 10mA, it produces 1nsec pulse without fuss.
Finding the broad-band PNPs to let you translate the output pulse to a
useful voltage level is tricky. Phil Hobbs has told us that there is a
least one still in production and available.
What a mess. The output pulse width just follows the input pulse
width. Unless you change C1, in which case it oscillates.
Actually, it doesn't. The input pulse has a full-width at half maximum
of 400psec, and the output pulse width is 1nsec, as intended
It's not a one-shot, it's a diffamp. Put in a 50 ns trigger and it
will make a 50 ns output.

And it makes the common beginner error of assuming that two
transistors are absolutely identical, and at the same temperature,
because Spice does that.

The critical 40 mV of diff offeset is derived by the diference between
the tweaked power supplies and, I suppose, two 1% resistors. That is
really weird. And unsafe.

The dangling wire scraps could roll around and short things.
Bill Sloman
2024-06-22 07:01:16 UTC
Permalink
Post by john larkin
Post by Bill Sloman
Post by john larkin
Post by Bill Sloman
Post by john larkin
On Wed, 12 Jun 2024 17:22:49 -0000 (UTC), Cursitor Doom
Post by john larkin
Post by john larkin
Here's another idea for a fast one-shot. This is the just-apply-money
version and should get close to 1 ns pulse width and should easily
trigger at 150 MHz.
https://www.dropbox.com/scl/fi/1okfo8964bw5m53mjmxs6/
Pecl_One_Shot_1.jpg?rlkey=dwus6qjyqsynl2rv6uje2xxtj&raw=1
Post by john larkin
I can use the other half of the dual comparator elsewhere. This one has
programmable hysteresis too.
Exposing my contemptworthy ignorance here no doubt, but what exactly is it
that is fast about this design, John? And what would its application be?
It would have a leading-edge prop delay of 350 ps, a minimum pulse
width just over 1 ns, and would easily trigger at 150 MHz. Integrated
one-shots, xxx123 types, are always terrible, even the obsolete ECL
ones.
It would be a programmable delay in a number of possible products,
including some optical modulators. Just playing right now.
More dollars could certainly do something faster, but as long as
customers connect boxes with cables, faster isn't worth a lot. Light
just moves too slow.
Any suggestions for a faster one-shot?
Version 4
SHEET 1 2924 1040
WIRE -592 -720 -768 -720
WIRE 128 -720 -592 -720
WIRE 304 -720 128 -720
WIRE 768 -720 304 -720
WIRE 976 -720 768 -720
WIRE 1488 -576 1488 -720
WIRE 128 -560 128 -720
WIRE 304 -560 304 -720
WIRE 768 -560 768 -720
WIRE -592 -384 -592 -720
WIRE 1072 -368 1072 -400
WIRE 768 -320 768 -480
WIRE 960 -320 768 -320
WIRE 1008 -320 960 -320
WIRE 128 -288 128 -480
WIRE 176 -288 128 -288
WIRE 576 -288 240 -288
WIRE 768 -208 768 -320
WIRE 304 -160 304 -480
WIRE 400 -160 304 -160
WIRE 576 -160 576 -288
WIRE 576 -160 480 -160
WIRE 640 -160 576 -160
WIRE 704 -160 640 -160
WIRE -768 -64 -768 -720
WIRE 128 48 128 -288
WIRE -272 96 -432 96
WIRE 64 96 -192 96
WIRE 640 128 640 -160
WIRE 304 160 304 -160
WIRE -432 240 -432 96
WIRE -768 416 -768 16
WIRE -768 416 -880 416
WIRE -736 416 -768 416
WIRE -592 416 -592 -320
WIRE -592 416 -736 416
WIRE -496 416 -592 416
WIRE -432 416 -432 320
WIRE -432 416 -496 416
WIRE 640 416 640 208
WIRE 640 416 -432 416
WIRE 1072 416 640 416
WIRE 128 464 128 144
WIRE 768 464 768 -112
WIRE 768 464 128 464
WIRE -880 496 -880 416
WIRE 768 496 768 464
WIRE -736 640 -736 416
WIRE -496 640 -496 416
WIRE -736 656 -736 640
WIRE -736 944 -736 720
WIRE -496 944 -496 704
WIRE -496 944 -736 944
WIRE 304 944 304 240
WIRE 304 944 -496 944
WIRE 768 944 768 576
WIRE 768 944 304 944
WIRE 1760 944 768 944
FLAG -880 496 0
FLAG 960 -320 out
SYMBOL npn 64 48 R0
SYMATTR InstName Q1
SYMATTR Value BFR92A
SYMBOL npn 704 -208 R0
SYMATTR InstName Q2
SYMATTR Value BFR92A
SYMBOL voltage -768 -80 R0
WINDOW 123 0 0 Left 0
WINDOW 39 24 44 Left 2
SYMATTR SpiceLine Rser=0.1
SYMATTR InstName V1
SYMATTR Value 5.0
SYMBOL voltage -736 624 R0
WINDOW 123 0 0 Left 0
WINDOW 39 24 44 Left 2
SYMATTR SpiceLine Rser=0.1
SYMATTR InstName V2
SYMATTR Value 4.5
SYMBOL voltage -432 224 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V3
SYMATTR Value PULSE(0 0.2 1n 300p 300p 100p 200n 2)
SYMBOL res -176 80 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R1
SYMATTR Value 22
SYMBOL res 752 480 R0
SYMATTR InstName R3
SYMATTR Value 360
SYMBOL res 112 -576 R0
SYMATTR InstName R4
SYMATTR Value 180
SYMBOL res 624 112 R0
SYMATTR InstName R5
SYMATTR Value 43
SYMBOL res 752 -576 R0
SYMATTR InstName R6
SYMATTR Value 180
SYMBOL res 288 -576 R0
SYMATTR InstName R2
SYMATTR Value 1k
SYMBOL cap 240 -304 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C1
SYMATTR Value 3.3p
SYMBOL res 288 144 R0
SYMATTR InstName R7
SYMATTR Value 1k2
SYMBOL res 496 -176 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R13
SYMATTR Value 43
SYMBOL cap -608 -384 R0
SYMATTR InstName C3
SYMATTR Value 10n
SYMBOL cap -512 640 R0
SYMATTR InstName C4
SYMATTR Value 10n
TEXT -272 1000 Left 2 !.model BFR92A NPN(IS=0.1213E-15 VAF=30 BF=94.73
IKF=0.46227 XTB=0 BR=10.729 CJC=946.47E-15 CJE=10.416E-15 TR=1.2744E-9
TF=26.796E-12 ITF=0.0044601 VTF=0.32861 XTF=0.3817 RB=14.998
RC=0.13793 RE=0.29088 Vceo=15 Icrating=4m mfg=Infineon)
TEXT -904 1024 Left 2 !.tran 0 500n 0
It's just a two transistor emitter-coupled monostable, but with the two
transistors as BFR92's run at 10mA, it produces 1nsec pulse without fuss.
Finding the broad-band PNPs to let you translate the output pulse to a
useful voltage level is tricky. Phil Hobbs has told us that there is a
least one still in production and available.
What a mess. The output pulse width just follows the input pulse
width. Unless you change C1, in which case it oscillates.
Actually, it doesn't. The input pulse has a full-width at half maximum
of 400psec, and the output pulse width is 1nsec, as intended
It's not a one-shot, it's a diffamp. Put in a 50 ns trigger and it
will make a 50 ns output.
Not that you have posted a sim that illustrates this.
Post by john larkin
And it makes the common beginner error of assuming that two
transistors are absolutely identical, and at the same temperature,
because Spice does that.
The critical 40 mV of diff offeset is derived by the difference between
the tweaked power supplies and, I suppose, two 1% resistors. That is
really weird. And unsafe.
It may not make any sense to you.

R2 and R7 deliver about about 0.8ma of bias current into the divider R13
+ R5. which normally biases Q2 on - with about 8.5mA of emitter current.
Q1 carries 1.5mA of emitter current.

You don't have to increase the base voltage of Q1 much to bias the pair
into an unstable state, in which the emitter current of Q1 rises to 10mA
then decays back to 1.5mA.

The excursion into instability is what produces the output pulse.
Post by john larkin
The dangling wire scraps could roll around and short things.
Not inside a sim. In real life this sort of circuit is always made as a
printed circuit board with traces running over ground plane - or at
least I've never done it any other way.
--
Bill Sloman, Sydney
--
This email has been checked for viruses by Norton antivirus software.
www.norton.com
piglet
2024-06-14 18:02:11 UTC
Permalink
Post by Bill Sloman
Post by john larkin
On Wed, 12 Jun 2024 17:22:49 -0000 (UTC), Cursitor Doom
Post by john larkin
Post by john larkin
Here's another idea for a fast one-shot. This is the just-apply-money
version and should get close to 1 ns pulse width and should easily
trigger at 150 MHz.
https://www.dropbox.com/scl/fi/1okfo8964bw5m53mjmxs6/
Pecl_One_Shot_1.jpg?rlkey=dwus6qjyqsynl2rv6uje2xxtj&raw=1
Post by john larkin
I can use the other half of the dual comparator elsewhere. This one has
programmable hysteresis too.
Exposing my contemptworthy ignorance here no doubt, but what exactly is it
that is fast about this design, John? And what would its application be?
It would have a leading-edge prop delay of 350 ps, a minimum pulse
width just over 1 ns, and would easily trigger at 150 MHz. Integrated
one-shots, xxx123 types, are always terrible, even the obsolete ECL
ones.
It would be a programmable delay in a number of possible products,
including some optical modulators. Just playing right now.
More dollars could certainly do something faster, but as long as
customers connect boxes with cables, faster isn't worth a lot. Light
just moves too slow.
Any suggestions for a faster one-shot?
Version 4
SHEET 1 2924 1040
WIRE -592 -720 -768 -720
WIRE 128 -720 -592 -720
WIRE 304 -720 128 -720
WIRE 768 -720 304 -720
WIRE 976 -720 768 -720
WIRE 1488 -576 1488 -720
WIRE 128 -560 128 -720
WIRE 304 -560 304 -720
WIRE 768 -560 768 -720
WIRE -592 -384 -592 -720
WIRE 1072 -368 1072 -400
WIRE 768 -320 768 -480
WIRE 960 -320 768 -320
WIRE 1008 -320 960 -320
WIRE 128 -288 128 -480
WIRE 176 -288 128 -288
WIRE 576 -288 240 -288
WIRE 768 -208 768 -320
WIRE 304 -160 304 -480
WIRE 400 -160 304 -160
WIRE 576 -160 576 -288
WIRE 576 -160 480 -160
WIRE 640 -160 576 -160
WIRE 704 -160 640 -160
WIRE -768 -64 -768 -720
WIRE 128 48 128 -288
WIRE -272 96 -432 96
WIRE 64 96 -192 96
WIRE 640 128 640 -160
WIRE 304 160 304 -160
WIRE -432 240 -432 96
WIRE -768 416 -768 16
WIRE -768 416 -880 416
WIRE -736 416 -768 416
WIRE -592 416 -592 -320
WIRE -592 416 -736 416
WIRE -496 416 -592 416
WIRE -432 416 -432 320
WIRE -432 416 -496 416
WIRE 640 416 640 208
WIRE 640 416 -432 416
WIRE 1072 416 640 416
WIRE 128 464 128 144
WIRE 768 464 768 -112
WIRE 768 464 128 464
WIRE -880 496 -880 416
WIRE 768 496 768 464
WIRE -736 640 -736 416
WIRE -496 640 -496 416
WIRE -736 656 -736 640
WIRE -736 944 -736 720
WIRE -496 944 -496 704
WIRE -496 944 -736 944
WIRE 304 944 304 240
WIRE 304 944 -496 944
WIRE 768 944 768 576
WIRE 768 944 304 944
WIRE 1760 944 768 944
FLAG -880 496 0
FLAG 960 -320 out
SYMBOL npn 64 48 R0
SYMATTR InstName Q1
SYMATTR Value BFR92A
SYMBOL npn 704 -208 R0
SYMATTR InstName Q2
SYMATTR Value BFR92A
SYMBOL voltage -768 -80 R0
WINDOW 123 0 0 Left 0
WINDOW 39 24 44 Left 2
SYMATTR SpiceLine Rser=0.1
SYMATTR InstName V1
SYMATTR Value 5.0
SYMBOL voltage -736 624 R0
WINDOW 123 0 0 Left 0
WINDOW 39 24 44 Left 2
SYMATTR SpiceLine Rser=0.1
SYMATTR InstName V2
SYMATTR Value 4.5
SYMBOL voltage -432 224 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V3
SYMATTR Value PULSE(0 0.2 1n 300p 300p 100p 200n 2)
SYMBOL res -176 80 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R1
SYMATTR Value 22
SYMBOL res 752 480 R0
SYMATTR InstName R3
SYMATTR Value 360
SYMBOL res 112 -576 R0
SYMATTR InstName R4
SYMATTR Value 180
SYMBOL res 624 112 R0
SYMATTR InstName R5
SYMATTR Value 43
SYMBOL res 752 -576 R0
SYMATTR InstName R6
SYMATTR Value 180
SYMBOL res 288 -576 R0
SYMATTR InstName R2
SYMATTR Value 1k
SYMBOL cap 240 -304 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C1
SYMATTR Value 3.3p
SYMBOL res 288 144 R0
SYMATTR InstName R7
SYMATTR Value 1k2
SYMBOL res 496 -176 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R13
SYMATTR Value 43
SYMBOL cap -608 -384 R0
SYMATTR InstName C3
SYMATTR Value 10n
SYMBOL cap -512 640 R0
SYMATTR InstName C4
SYMATTR Value 10n
TEXT -272 1000 Left 2 !.model BFR92A NPN(IS=0.1213E-15 VAF=30 BF=94.73
IKF=0.46227  XTB=0 BR=10.729 CJC=946.47E-15 CJE=10.416E-15 TR=1.2744E-9
TF=26.796E-12  ITF=0.0044601 VTF=0.32861  XTF=0.3817 RB=14.998
RC=0.13793 RE=0.29088 Vceo=15 Icrating=4m mfg=Infineon)
TEXT -904 1024 Left 2 !.tran 0 500n 0
It's just a two transistor emitter-coupled monostable, but with the two
transistors as BFR92's run at 10mA,  it produces 1nsec pulse without fuss.
Finding the broad-band PNPs to let you translate the output pulse to a
useful voltage level is tricky. Phil Hobbs has told us that there is a
least one still in production and available.
It is a pity it relies on an input pulse shorter than the output - at
those speeds it would nicer to have a step input somehow?

piglet
Bill Sloman
2024-06-22 03:20:00 UTC
Permalink
Post by piglet
Post by Bill Sloman
Post by john larkin
On Wed, 12 Jun 2024 17:22:49 -0000 (UTC), Cursitor Doom
Post by john larkin
Post by john larkin
Here's another idea for a fast one-shot. This is the just-apply-money
version and should get close to 1 ns pulse width and should easily
trigger at 150 MHz.
https://www.dropbox.com/scl/fi/1okfo8964bw5m53mjmxs6/
Pecl_One_Shot_1.jpg?rlkey=dwus6qjyqsynl2rv6uje2xxtj&raw=1
Post by john larkin
I can use the other half of the dual comparator elsewhere. This one has
programmable hysteresis too.
Exposing my contemptworthy ignorance here no doubt, but what exactly is it
that is fast about this design, John? And what would its application be?
It would have a leading-edge prop delay of 350 ps, a minimum pulse
width just over 1 ns, and would easily trigger at 150 MHz. Integrated
one-shots, xxx123 types, are always terrible, even the obsolete ECL
ones.
It would be a programmable delay in a number of possible products,
including some optical modulators. Just playing right now.
More dollars could certainly do something faster, but as long as
customers connect boxes with cables, faster isn't worth a lot. Light
just moves too slow.
Any suggestions for a faster one-shot?
Version 4
SHEET 1 2924 1040
WIRE -592 -720 -768 -720
WIRE 128 -720 -592 -720
WIRE 304 -720 128 -720
WIRE 768 -720 304 -720
WIRE 976 -720 768 -720
WIRE 1488 -576 1488 -720
WIRE 128 -560 128 -720
WIRE 304 -560 304 -720
WIRE 768 -560 768 -720
WIRE -592 -384 -592 -720
WIRE 1072 -368 1072 -400
WIRE 768 -320 768 -480
WIRE 960 -320 768 -320
WIRE 1008 -320 960 -320
WIRE 128 -288 128 -480
WIRE 176 -288 128 -288
WIRE 576 -288 240 -288
WIRE 768 -208 768 -320
WIRE 304 -160 304 -480
WIRE 400 -160 304 -160
WIRE 576 -160 576 -288
WIRE 576 -160 480 -160
WIRE 640 -160 576 -160
WIRE 704 -160 640 -160
WIRE -768 -64 -768 -720
WIRE 128 48 128 -288
WIRE -272 96 -432 96
WIRE 64 96 -192 96
WIRE 640 128 640 -160
WIRE 304 160 304 -160
WIRE -432 240 -432 96
WIRE -768 416 -768 16
WIRE -768 416 -880 416
WIRE -736 416 -768 416
WIRE -592 416 -592 -320
WIRE -592 416 -736 416
WIRE -496 416 -592 416
WIRE -432 416 -432 320
WIRE -432 416 -496 416
WIRE 640 416 640 208
WIRE 640 416 -432 416
WIRE 1072 416 640 416
WIRE 128 464 128 144
WIRE 768 464 768 -112
WIRE 768 464 128 464
WIRE -880 496 -880 416
WIRE 768 496 768 464
WIRE -736 640 -736 416
WIRE -496 640 -496 416
WIRE -736 656 -736 640
WIRE -736 944 -736 720
WIRE -496 944 -496 704
WIRE -496 944 -736 944
WIRE 304 944 304 240
WIRE 304 944 -496 944
WIRE 768 944 768 576
WIRE 768 944 304 944
WIRE 1760 944 768 944
FLAG -880 496 0
FLAG 960 -320 out
SYMBOL npn 64 48 R0
SYMATTR InstName Q1
SYMATTR Value BFR92A
SYMBOL npn 704 -208 R0
SYMATTR InstName Q2
SYMATTR Value BFR92A
SYMBOL voltage -768 -80 R0
WINDOW 123 0 0 Left 0
WINDOW 39 24 44 Left 2
SYMATTR SpiceLine Rser=0.1
SYMATTR InstName V1
SYMATTR Value 5.0
SYMBOL voltage -736 624 R0
WINDOW 123 0 0 Left 0
WINDOW 39 24 44 Left 2
SYMATTR SpiceLine Rser=0.1
SYMATTR InstName V2
SYMATTR Value 4.5
SYMBOL voltage -432 224 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V3
SYMATTR Value PULSE(0 0.2 1n 300p 300p 100p 200n 2)
SYMBOL res -176 80 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R1
SYMATTR Value 22
SYMBOL res 752 480 R0
SYMATTR InstName R3
SYMATTR Value 360
SYMBOL res 112 -576 R0
SYMATTR InstName R4
SYMATTR Value 180
SYMBOL res 624 112 R0
SYMATTR InstName R5
SYMATTR Value 43
SYMBOL res 752 -576 R0
SYMATTR InstName R6
SYMATTR Value 180
SYMBOL res 288 -576 R0
SYMATTR InstName R2
SYMATTR Value 1k
SYMBOL cap 240 -304 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C1
SYMATTR Value 3.3p
SYMBOL res 288 144 R0
SYMATTR InstName R7
SYMATTR Value 1k2
SYMBOL res 496 -176 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R13
SYMATTR Value 43
SYMBOL cap -608 -384 R0
SYMATTR InstName C3
SYMATTR Value 10n
SYMBOL cap -512 640 R0
SYMATTR InstName C4
SYMATTR Value 10n
TEXT -272 1000 Left 2 !.model BFR92A NPN(IS=0.1213E-15 VAF=30 BF=94.73
IKF=0.46227  XTB=0 BR=10.729 CJC=946.47E-15 CJE=10.416E-15
TR=1.2744E-9 TF=26.796E-12  ITF=0.0044601 VTF=0.32861  XTF=0.3817
RB=14.998 RC=0.13793 RE=0.29088 Vceo=15 Icrating=4m mfg=Infineon)
TEXT -904 1024 Left 2 !.tran 0 500n 0
It's just a two transistor emitter-coupled monostable, but with the
two transistors as BFR92's run at 10mA,  it produces 1nsec pulse
without fuss.
Finding the broad-band PNPs to let you translate the output pulse to a
useful voltage level is tricky. Phil Hobbs has told us that there is a
least one still in production and available.
It is a pity it relies on an input pulse shorter than the output - at
those speeds it would nicer to have a step input somehow?
If you have a long input pulse you can use a delay line and an AND gate
to make a shorter one. That was how I got 0.5nsec +/- 0.05nsec at
Cambridge Instruments in their 1985 electron beam tester's beam blanking
system.
--
Bill Sloman, Sydney
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john larkin
2024-06-22 05:23:30 UTC
Permalink
Post by piglet
Post by Bill Sloman
Post by john larkin
On Wed, 12 Jun 2024 17:22:49 -0000 (UTC), Cursitor Doom
Post by john larkin
Post by john larkin
Here's another idea for a fast one-shot. This is the just-apply-money
version and should get close to 1 ns pulse width and should easily
trigger at 150 MHz.
https://www.dropbox.com/scl/fi/1okfo8964bw5m53mjmxs6/
Pecl_One_Shot_1.jpg?rlkey=dwus6qjyqsynl2rv6uje2xxtj&raw=1
Post by john larkin
I can use the other half of the dual comparator elsewhere. This one has
programmable hysteresis too.
Exposing my contemptworthy ignorance here no doubt, but what exactly is it
that is fast about this design, John? And what would its application be?
It would have a leading-edge prop delay of 350 ps, a minimum pulse
width just over 1 ns, and would easily trigger at 150 MHz. Integrated
one-shots, xxx123 types, are always terrible, even the obsolete ECL
ones.
It would be a programmable delay in a number of possible products,
including some optical modulators. Just playing right now.
More dollars could certainly do something faster, but as long as
customers connect boxes with cables, faster isn't worth a lot. Light
just moves too slow.
Any suggestions for a faster one-shot?
Version 4
SHEET 1 2924 1040
WIRE -592 -720 -768 -720
WIRE 128 -720 -592 -720
WIRE 304 -720 128 -720
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FLAG -880 496 0
FLAG 960 -320 out
SYMBOL npn 64 48 R0
SYMATTR InstName Q1
SYMATTR Value BFR92A
SYMBOL npn 704 -208 R0
SYMATTR InstName Q2
SYMATTR Value BFR92A
SYMBOL voltage -768 -80 R0
WINDOW 123 0 0 Left 0
WINDOW 39 24 44 Left 2
SYMATTR SpiceLine Rser=0.1
SYMATTR InstName V1
SYMATTR Value 5.0
SYMBOL voltage -736 624 R0
WINDOW 123 0 0 Left 0
WINDOW 39 24 44 Left 2
SYMATTR SpiceLine Rser=0.1
SYMATTR InstName V2
SYMATTR Value 4.5
SYMBOL voltage -432 224 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
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SYMATTR Value PULSE(0 0.2 1n 300p 300p 100p 200n 2)
SYMBOL res -176 80 R90
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WINDOW 3 32 56 VTop 2
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SYMATTR Value 22
SYMBOL res 752 480 R0
SYMATTR InstName R3
SYMATTR Value 360
SYMBOL res 112 -576 R0
SYMATTR InstName R4
SYMATTR Value 180
SYMBOL res 624 112 R0
SYMATTR InstName R5
SYMATTR Value 43
SYMBOL res 752 -576 R0
SYMATTR InstName R6
SYMATTR Value 180
SYMBOL res 288 -576 R0
SYMATTR InstName R2
SYMATTR Value 1k
SYMBOL cap 240 -304 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C1
SYMATTR Value 3.3p
SYMBOL res 288 144 R0
SYMATTR InstName R7
SYMATTR Value 1k2
SYMBOL res 496 -176 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R13
SYMATTR Value 43
SYMBOL cap -608 -384 R0
SYMATTR InstName C3
SYMATTR Value 10n
SYMBOL cap -512 640 R0
SYMATTR InstName C4
SYMATTR Value 10n
TEXT -272 1000 Left 2 !.model BFR92A NPN(IS=0.1213E-15 VAF=30 BF=94.73
IKF=0.46227  XTB=0 BR=10.729 CJC=946.47E-15 CJE=10.416E-15 TR=1.2744E-9
TF=26.796E-12  ITF=0.0044601 VTF=0.32861  XTF=0.3817 RB=14.998
RC=0.13793 RE=0.29088 Vceo=15 Icrating=4m mfg=Infineon)
TEXT -904 1024 Left 2 !.tran 0 500n 0
It's just a two transistor emitter-coupled monostable, but with the two
transistors as BFR92's run at 10mA,  it produces 1nsec pulse without fuss.
Finding the broad-band PNPs to let you translate the output pulse to a
useful voltage level is tricky. Phil Hobbs has told us that there is a
least one still in production and available.
It is a pity it relies on an input pulse shorter than the output - at
those speeds it would nicer to have a step input somehow?
piglet
It's really a slow diffamp, not a one-shot. It will make a nice clean
1 second output, given a 1 second trigger input.
Bill Sloman
2024-06-23 01:38:28 UTC
Permalink
Post by john larkin
Post by john larkin
On Wed, 12 Jun 2024 17:22:49 -0000 (UTC), Cursitor Doom
<snip>
Post by john larkin
It's really a slow diffamp, not a one-shot. It will make a nice clean
1 second output, given a 1 second trigger input.
It isn't. John could have tried to simulate his "one second trigger
input", if he could have worked out what he meant by that.

And it is hard to make a really slow differential amplifier out of a
BFR92 long-tailed pair.

He got very excited about the 43mV threshold voltage. Just for fun, I
increased R7 in my simulation from 1k2 to 1k5, which doubles the threshold.

The same trigger pulse gave a visually identical output pulse. My guess
is that it will be picoseconds later and picoseconds narrower, but I'm
not going to make a meal of it by actually measuring the differences.
--
Bill Sloman, Sydney
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Cursitor Doom
2024-06-23 17:01:45 UTC
Permalink
Post by Bill Sloman
Post by john larkin
On Wed, 12 Jun 2024 17:22:49 -0000 (UTC), Cursitor Doom
<snip>
It's really a slow diffamp, not a one-shot. It will make a nice clean 1
second output, given a 1 second trigger input.
It isn't. John could have tried to simulate his "one second trigger
input", if he could have worked out what he meant by that.
And it is hard to make a really slow differential amplifier out of a
BFR92 long-tailed pair.
He got very excited about the 43mV threshold voltage. Just for fun, I
increased R7 in my simulation from 1k2 to 1k5, which doubles the threshold.
The same trigger pulse gave a visually identical output pulse. My guess
is that it will be picoseconds later and picoseconds narrower, but I'm
not going to make a meal of it by actually measuring the differences.
--
Bill Sloman, Sydney
When I needed a design for a fast pulse generator, Jim Thompson very
kindly came up with the goods for me and was happy to do it for free. Jim
designed quite a lot of bits and pieces for me over the years. He was a
*genuine* contributor in the true spirit of mutual assistance that the
'net used to be all about. You could learn a thing or two from Jim's
exemplary conduct here, Bill. Stop being a condescending wanker and chip-
in something useful for a change.
john larkin
2024-06-23 17:36:35 UTC
Permalink
On Sun, 23 Jun 2024 17:01:45 -0000 (UTC), Cursitor Doom
Post by Cursitor Doom
Post by Bill Sloman
Post by john larkin
On Wed, 12 Jun 2024 17:22:49 -0000 (UTC), Cursitor Doom
<snip>
It's really a slow diffamp, not a one-shot. It will make a nice clean 1
second output, given a 1 second trigger input.
It isn't. John could have tried to simulate his "one second trigger
input", if he could have worked out what he meant by that.
And it is hard to make a really slow differential amplifier out of a
BFR92 long-tailed pair.
He got very excited about the 43mV threshold voltage. Just for fun, I
increased R7 in my simulation from 1k2 to 1k5, which doubles the threshold.
The same trigger pulse gave a visually identical output pulse. My guess
is that it will be picoseconds later and picoseconds narrower, but I'm
not going to make a meal of it by actually measuring the differences.
--
Bill Sloman, Sydney
When I needed a design for a fast pulse generator, Jim Thompson very
kindly came up with the goods for me and was happy to do it for free. Jim
designed quite a lot of bits and pieces for me over the years. He was a
*genuine* contributor in the true spirit of mutual assistance that the
'net used to be all about. You could learn a thing or two from Jim's
exemplary conduct here, Bill. Stop being a condescending wanker and chip-
in something useful for a change.
There are some screamong fast CMOS gates and flops around that cost
pennies.
Bill Sloman
2024-06-24 02:34:58 UTC
Permalink
Post by john larkin
On Sun, 23 Jun 2024 17:01:45 -0000 (UTC), Cursitor Doom
Post by john larkin
On Wed, 12 Jun 2024 17:22:49 -0000 (UTC), Cursitor Doom
<snip>
Post by john larkin
There are some screamingly fast CMOS gates and flops around that cost
pennies.
And there have been for years. You started this thread with a pencil
sketch that included an 10EP51 ($6.53) and an ADCMP562 ($3.15).

Two BFR92 ($0.64 each)and couple of resistors and capacitors can do the
same job, if you know what you are doing.

You pencil sketch didn't tell us much about what you were trying to do,
or why, and nothing much about the input - "Trig In" as a balanced PECL
signal tells us about the signal levels, but nothing else.

As an effort to look like a circuit designer, it wasn't impressive.
--
Bill Sloman, Sydney
--
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Bill Sloman
2024-06-24 02:10:10 UTC
Permalink
Post by Cursitor Doom
Post by Bill Sloman
Post by john larkin
On Wed, 12 Jun 2024 17:22:49 -0000 (UTC), Cursitor Doom
<snip>
It's really a slow diffamp, not a one-shot. It will make a nice clean 1
second output, given a 1 second trigger input.
It isn't. John could have tried to simulate his "one second trigger
input", if he could have worked out what he meant by that.
And it is hard to make a really slow differential amplifier out of a
BFR92 long-tailed pair.
He got very excited about the 43mV threshold voltage. Just for fun, I
increased R7 in my simulation from 1k2 to 1k5, which doubles the threshold.
The same trigger pulse gave a visually identical output pulse. My guess
is that it will be picoseconds later and picoseconds narrower, but I'm
not going to make a meal of it by actually measuring the differences.
When I needed a design for a fast pulse generator, Jim Thompson very
kindly came up with the goods for me and was happy to do it for free.
Pointed you at the right application note? Most of the work in doing
that is finding out what you actually wanted to do.
Post by Cursitor Doom
Jim designed quite a lot of bits and pieces for me over the years. He was a
*genuine* contributor in the true spirit of mutual assistance that the
'net used to be all about.
He was a contract integrated circuit designer, and got paid for anything
serious. At one point he claimed that he had denounced me to the FBI for
being "dangerously anti-American". That "true spirit of mutual
assistance" came with a certain amount of unpleasant baggage.
Post by Cursitor Doom
You could learn a thing or two from Jim's exemplary conduct here, Bill. Stop being a condescending wanker and chip-
in something useful for a change.
Just like you do?
--
Bill Sloman, Sydney
--
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