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From: piglet <erichpwagner@hotmail.com>
Newsgroups: sci.electronics.design
Subject: Re: another fast one-shot
Date: Fri, 14 Jun 2024 19:02:11 +0100
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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
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> 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
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