common mode problem in pipelined ADC

Hi i have some problem about my pipelined ADC. i have designed SC amplifier for my MDAC. i already check their function and it work, but when i connect the first and secound stage together then the first stage common mode has change (i still use ideal switch and non-ideal opamp but real comparators). Anybody know what is happen with my first stage? thanks.

What 's structure do you use On S/H , It is depend on S?h structure , You can reference
http://kabuki.eecs.berkeley.edu/adc/adc.html
This web site , you can see the doc . find the result

thank you

No ' thanks ' here.
Warning!

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makswell

For the Sample and Hold design ...u can also refer the design explained in Ken Martin.

I have used it in my project and

I have included as much schematics as possible.

The track and hold circuit i used is based on the open loop miller hold capacitance.

http://jennisjose.webs.com/pipelinedadc.htm