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overshooting
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mattholland
May 17, 2008, 3:03:49 AM5/17/08
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i had a lot of headaches with my output overshooting it's value by as
much as 0.7~0.8%, especially with the gain=16 input=0.4/16 cases. I
think it might have been related to charge injection from the switch
that connects to the inverting input. the inverting input drops by
about 5mv in the time between phi1 being low and phi2 going high, and
increasing the size of the switch (to increase its capacitance) makes
it drop more. Increasing C2 didn't seem to help. Did anyone else
encounter this and discover the cause?
much as 0.7~0.8%, especially with the gain=16 input=0.4/16 cases. I
think it might have been related to charge injection from the switch
that connects to the inverting input. the inverting input drops by
about 5mv in the time between phi1 being low and phi2 going high, and
increasing the size of the switch (to increase its capacitance) makes
it drop more. Increasing C2 didn't seem to help. Did anyone else
encounter this and discover the cause?
mh
A Lee
May 17, 2008, 3:28:12 AM5/17/08
to
using a small sized butterfly at the output helped take off some
charge injection. also, increasing the size of the caps reduced the
effect of the extra charges too. i didnt have any oscillations, but
some voltage offsets were taken away for me.
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