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Design >> Analog Design >> Virtual ground in switched capacitor integrator
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Message started by jdp on Feb 27^th, 2016, 4:39am

Title: Virtual ground in switched capacitor integrator
Post by jdp on Feb 27^th, 2016, 4:39am

Hi,
In a switched capacitor integrator (figure attached), it is said that the inverting input terminal of the op-amp is a virtual ground. How can we explain that? - because there is no resistor used in parallel to the feedback capacitor to ensure negative feedback!

Title: Re: Virtual ground in switched capacitor integrator
Post by raja.cedt on Feb 27^th, 2016, 8:33am

Interesting Question. During Phase-2, you have -ve feedback because of the capacitive potential divider. You need a resister in case if you have resister the opamp input like we do have in case of integrator.

Hope this helps,
Raj.

Title: Re: Virtual ground in switched capacitor integrator
Post by jdp on Feb 27^th, 2016, 7:31pm

Thanks Raja for your explanation !!