Re: The emitter-coupled monostable as slow differential amplifer

On Sat, 20 Jul 2024 15:29:58 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:

About a month ago John Larkin dismissed the emitter coupled monostable
with "It's really a slow diffamp, not a one-shot."
>
If you feed a really slow pulse into it, it can look that way.
The 3.3pf capacitor at C1 doesn't feed through much current if you drive
the input with a slow edge
>
The simulation below demonstrates it working exactly that way.
>
No sensible circuit designer would deliberately drive it with a very
slowly rising and falling pulse  - if you want it to work as a
monostable pulse stretcher, you have to drive it with a pulse that is
narrower than the one you want to get out.
>
Integrated circuit monostables don't have that limitation, but they are
more complicated, and slower. There was an ECL monostable that went down
to 10nsec, but the emitter-coupled monostable lets you get down to
1nsec, if you use it right.
>
Version 4
SHEET 1 3104 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 2
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 2
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 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V3
SYMATTR Value PULSE(0 0.2 1n 100n 100n 100p 500n 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 1k5
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 1u 0
>
--
Bill Sloman, Sydney

Which LTspice version are you using ?  These .asc files always seem to
show version 4  at the top but there have been many after that.

Version 24 says it does not know the schematic syntax of these lines:


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)

I remove those and it is an incomplete schematic.

I keep my old LTspice install exe's but just using 24 now

boB