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  1. #1
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    A kind of tuning circuit in Gm-C filter

    Hi, all:

    I design tuning circuits for gm-c filter to compensate the gm's variation due to process,temperature and aging.
    My reference is form the book"Wireless.Communication.Circuits.And.Systems", and details in accessories. But I have some questions below,please help me check them.

    1.The Gm cell in the “Tuning circuits” (accessories) is single-ended or should be balanced ,just like those gm cells in filter ?

    2. I was confused by those sentences “The arrangement uses a control loop comprising a skewed ‘diode-connected’ transconductor −G0 which generates a quiescent voltage which is offset from that of the reference transconductor” What does “offset” mean? How to explain it ?

    Thanks!!


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  2. #2
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    Re: A kind of tuning circuit in Gm-C filter

    Hi, friend
    1, I think you should use the same Gm cell as that in filter.
    In fact, I use the Gm cell in filter as a part of tuning circuit. So balanced one should be used.
    2, I think 'offset' is a DC difference. You should refer to the whole design to explain it. But the purpose of it is to make sure the gm cell is same with that in filter.

    Good luck


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  3. #3
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    Re: A kind of tuning circuit in Gm-C filter

    Hi,jecyhale

    Thanks for your kind help! The whole design reference paper is attached .

    I designed the tuning circuits based on single-end gm cell, You said this tuing circits should use balanced gm cell , I think this will be better for "master-slave" tuning.
    But how to transfer this single-end tuning to balanced one?

    1. The inverter can be replaced by comparator ?

    2. which kind of tuning circuits have you used in practice gm-c filter design ?
    Is it using PLL ?


    Thanks!



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