Comparaor offset measurement

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rty94

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Hello, I am trying to measure via cadence the offset for a comparator. I would like it is a way using DC analysis+hysterisis sweep? how could I sweep properly input voltages in this case?

Thanks!
 

You will not get a good measurement using triangle
wave input sweeps, the variable prop delay w/
overdrive level will make results dependent on ramp
rate even if you don't get a "chatter band" on the
'scope.

The best way I've seen is to use a classical op amp
test loop, with threshold set to (VOH+VOL)/2, and let
the output chatter be assumed symmetric. The aux
amp integration provides filtering to a quasi-DC and
the Vio (along with IIB, IIO, CMRR, PSRR, AVOL) can be
made pretty repeatable.
 

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  • simple-op-amp-measurements.pdf
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If I remember correctly the .dc sweep must be done from min to max value (voltage range on X-axis) with a given step and then back. .The op point calculated for a given step should be used to calculate .op for the next step.
 

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