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  1. #1
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    A question about common input of OTA in ADC

    Hi All,
    I am a beginner in Analog ADC design. Attached is a T/H circuit. I think that in order for the OTA to function, common mode input is needed to set the operational point. Does this circuit only show the signal path not including the common input at all? Do we need addtional switch circuit to connect to the VCM1? If yes, what is the general and reliable way people do? how about a differential case? Please give me advice and some good references.

    Thanks.

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  2. #2
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    A question about common input of OTA in ADC

    Look for thesis and articles from Sumanen and Waltari (Helsinki). They both have worked extensively about ADC's designs.



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  3. #3
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    Re: A question about common input of OTA in ADC

    No S3 sets the OTA input common-mode- you can use the same idea for a fully-differential amplifier. Also, it means you are using an OTA which can have same input and output common mode.

    Bupesh



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