Re: another fast one-shot

On 13/06/2024 07:03, Bill Sloman wrote:

On 13/06/2024 4:11 am, john larkin wrote:

On Wed, 12 Jun 2024 17:22:49 -0000 (UTC), Cursitor Doom
<cd999666@notformail.com> wrote:
>

On Wed, 12 Jun 2024 09:33:17 -0700, john larkin wrote:
>

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

>
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