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  1. #1
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    folded cascode offset

    Hello,

    Anybody knows how to calculate the random input offset voltage of the folded-cascode operational amplifier by hand?
    I need to find 3sigma offset, knowing sigma beta and sigma threshold according to the Pelgrom model.
    If you know some literature, please tell me.
    Thank you.

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  2. #2
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    input offset folded cascode amp

    mm...
    I think Razavi' book is very clear, reference the chapter about nonlinearity and match.
    For folded cascode, the offset are mainly from input pairs and active current source.



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    folded cascode matching

    Check the book Design of Low-Voltage Low-Power Operational Amplifier Cells by Ron Hogervorst. Also check this pdf. It has all the Pelgrom's equations and offset equations for the folded cascode OTA.

    http://www.utdallas.edu/~hellums/doc...7/Matching.pdf



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    how to calculate offset voltage

    Quote Originally Posted by gsuarez
    Also check this pdf. It has all the Pelgrom's equations and offset equations for the folded cascode OTA.

    http://www.utdallas.edu/~hellums/doc...7/Matching.pdf

    I have some doubt about this article. Especially, I was laughing, when in section 5.2 author chose length of transistor 20um and 32um :)).



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    folded cascode offset calculation

    assuming that the transconductance of input pair is large compared to that of load, the mismatch of input pair is the random offset



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