OTA as an integrator

Discussion in 'General Electronics Chat' started by salil87, Sep 2, 2013.

  1. salil87

    Thread Starter New Member

    Nov 4, 2011
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    Hi
    I just want to get some idea how to use an OTA as an integrator (for dual slope ADC). Can some one help me out or give me some links?
    Thanks
    Salil
     
  2. BillB3857

    Senior Member

    Feb 28, 2009
    2,400
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  3. LvW

    Active Member

    Jun 13, 2013
    674
    100
    Hi salil,
    do you know how a voltage opamp is used as an (inverting) integrator?

    You can use the same principle (feedback capacitor) for OTA`s also.
    However, the transfer function looks a bit more complicated (it contains the finite transconductance gm of the OTA).
    More than that, there is a disturbing constant term, which however can be kept small for proper design.

    But note that you need an output buffer (unity gain amplifier).
     
  4. analogdesign

    New Member

    Aug 29, 2013
    14
    1
    Conceptually, all you need to do is load the OTA with a capacitor to make an integrator. If the OTA is very low gain, this could work, but open-loop signal processing is an advanced topic. In practice you should use negative feedback like as if you were using an op amp. You only need an output stage if you're driving a resistive load.
     
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