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From: john larkin <jl@650pot.com>
Newsgroups: sci.electronics.design
Subject: Re: another fast one-shot
Date: Fri, 21 Jun 2024 22:23:30 -0700
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On Fri, 14 Jun 2024 19:02:11 +0100, piglet <erichpwagner@hotmail.com>
wrote:

>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?
>
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