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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 22:20:31 -0700
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On Sat, 22 Jun 2024 13:13:44 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:

>On 14/06/2024 1:31 am, john larkin wrote:
>> On Thu, 13 Jun 2024 16:03:04 +1000, Bill Sloman <bill.sloman@ieee.org>
>> 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.
>> 
>> What a mess. The output pulse width just follows the input pulse
>> width. Unless you change C1, in which case it oscillates.
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