The Designer's Guide Community Forum

The Designer's Guide Community Forum
https://designers-guide.org/forum/YaBB.pl
Design >> Analog Design >> chopper stabilization amplifier question
https://designers-guide.org/forum/YaBB.pl?num=1147818847

Message started by chungmnig on May 16^th, 2006, 3:34pm

Title: chopper stabilization amplifier question
Post by chungmnig on May 16^th, 2006, 3:34pm

Hi~~
i designed a chopper amplifier
the differential output signal like attached file.
why the spike is so large?
can anybody now why ,is it normal?

i often see the output signal will into a low pass filter.
is when go into the low pass filter the spikes will disappear.
thanks a lot

Title: Re: chopper stabilization amplifier question
Post by Jerome on Jul 4^th, 2006, 2:03am

Hello Chungmnig,

You are right: the low pass filter is meant to remove spikes.
One thing you should aware of: even if spikes are removed,
they contribute to the offset. The offset is strictly proportional
to the frequency (that is why high precision chopper use low
chopping frequency).
I got a chopper back from the fab last year. It is paced at
2MHz (a bit like yours). I have measured an offset 150uV
due to charge injection. This offset was strictly proportional
to the chopping frequency (<100uV at 1MHz).

If I were you, you would try to decrease the amplitude and
the duration of the spike.

Good luck, Jerome.

Title: Re: chopper stabilization amplifier question
Post by RobG on Jul 5^th, 2006, 12:39pm

I'd be a bit worried because the size of the spikes seem to be signal dependent.