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Design >> Analog Design >> Offset cancelled comparator layout
https://designers-guide.org/forum/YaBB.pl?num=1264460465

Message started by jiesteve on Jan 25^th, 2010, 3:01pm

Title: Offset cancelled comparator layout
Post by jiesteve on Jan 25^th, 2010, 3:01pm

In an offset cancelled comparator layout, is it still important to use precise matching layout techniques (i.e. interdigitation, common centroid layout, dummies, etc) or can the layout be somewhat "relaxed", since the offset contributions from imperfect layout will be cancelled anyway?

Title: Re: Offset cancelled comparator layout
Post by thechopper on Jan 25^th, 2010, 4:12pm

Hi jiesteve,

Usually it is still important to keep good layout practices since the idea behind any offset cancellation technique is to do so on random offsets and not systematic ones (that could be created due to bad layout practices).
How critical is the extra amount of offset that you have to process due to bad layout practice will depend on the chosen technique.
For chopper stabilization, for example, it might have some impact since there is a limited headroom for proper modulation of the offset component without generating residual offset.

I would strongly suggest for the majority of the cases following the same rules as if you were not cancelling any offset.

Best
Tosei

Title: Re: Offset cancelled comparator layout
Post by jiesteve on Jan 25^th, 2010, 4:37pm

Thanks Tosei, this makes sense.