How to cancel charge injection??

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menewbie

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How to cancel charge injection that is induced by the CMOS transmission gate?
I know for NMOS switches, one can use dummy switches. But for CMOS transmission gates, using dummy switches doesnt work...
 

what is the meaning of bottom sampling?
 

I dont think bottom plate sampling helps in reducing charge injection. Its done to eliminate the effect of parasitic caps(from substrate). Here you place the sampling capacitor such that it's bottom plate is facing the input of the sample and hold. Refer Baker and Boyce book for more information.

You can use fully differential topology to eliminate first order charge injection.
 

I think the concept n remedy o charge injection is explained beautifully in Analo Integrated Circuits-Ken n Martin ; the book is available on the board.
so, just look up.
 

Hi menewbie, what is the cap size and the switches size that you use? I'm quite baffled when you said that dummy switches cannot reduce charge injection for transmission gates. Do try to add some delay to turning on the dummy switches to see if that helps. I agree that fully differential circuit topology helps much.
 

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