Comparator offset problem

[Amr.Ibrahim]

I was designing rail to rail latched comparator and when I measure the offset this histogram appear to me. I wanna know what may be the reason for this far occurrence between -20 and -30 and Is this due ti rail to rail and how can I solve this problem?

Thanks in advance
Regards,
Amr

 

[dick_freebird]

You can solve the problem by

1) identifying the specific MC iteration(s) responsible

2) assert one specific iteration and rerun the analysis
(same MC mode / settings, set the index, run, check
that the same post-analysis retuens the same offending
result)

3) Inspect operation for what's whacked

This might be a gain shortfall at one end of the Leff
range (and you should then inspect the imposed Leff
position, relative to WAT spec), a failure to start up
in the master bias reference or a way-off bias level,
some gross mismatch in N vs P VT / IDsat (skewing
inverter thresholds and pushing back into the front
end), etc. You could speculate all day, so get on with
the task of making a single MC iteration repeatable
and accessible in a foreground simulation environment.