Monostable multivibrator simulation problem in Cadence Spectre

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acbalbason

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Hi Guys,

I tried my hands in simulating a simple one shot monostable multivbator in Spectre. I am getting the wrong output for some reason. Is it because the trigger signal is too short? I put it at 1us pulse width. Even when I changed it to 10us, I still don't get the correct output. I tried to vary the RC element which should determine the Tau of the output waveform, to no avail. Can you help?

I was using this as reference: The One-shot Monostable Multivibrator

Thank you!

Al
 

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V-driving the drain of that leftmost transistor means that transistor
does nothing but waste current. The whole thing is a wireball to me.
If I was doing this for a product I'd spend the extra transistors and
do a foolproof state machine (SRFF driving discharge switch, SRFF
driven by trigger & discharge and reset by ramp top).

Maybe the IN node wants a different form of drive.
 

Hello
This is my circuit with slight modifications

The input and output waveforms are the following:

So everything works fine)
Regards.
 
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