Hi all,
    I have a clocked comparator with positive feedback. I need to cancel offset in that comparator . My offset should be less than 0.3mV. Please suggest me some way.
Since my comparator is highly non linear, how to do auto zeroing as feedback operatiionis linear

Agreed with you. But the problem with having preamp is the power consumption. So only was wondering is it possible to have some offset cancellation technique in comparator only

Thanks Jerry,
                  The references deal with canceling offset for a comparator which has a constant gain or the system isLTI system.
If u have a comparator with positive feedback and transistors operating in every region we cannot use negative feedback to detect the offset.
So the question is how to go about solving offset in these comparators.
One such example of a comparator is clocked sense amplifier used in SRAM.
Thanks
Rakesh

Hi,
  True, If i need the offset to be less than 500uV, designing the switching of current sources and the open loop calibration with low power is rather difficult
Thanks
Rakesh

Hi,

Maybe you can apply a known ramp to the comparator and measure the time it takes for the comparator to toggle? Or two ramps, if the offset is decision-dependent.

Probably not fast enough to do for every sample, but maybe useful to tune a feedforward compensation?

sounds like you want a static system. That said, the prior suggestions of injecting offset are possibilities.

I have also seen changing the geometry (switching pieces in and out) of the loads above the differential pairs, and other size changes (using switches again) of various pieces.

You got to run an alignment circuit every once in a while.