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AC Coupling output - is this capacitive load?

Kevin Hughes
Intellectual 300 points
Other Parts Discussed in Thread: LMV861, OPA4322

Hello,

We are using the LMV861 as a 10x gain amp, and need to AC couple the output.  Its datasheet lists a capacitive load tolerance of up to 200pF.  Our circuit needs 2.7nF in an AC coupling configuration, with no other load on the output of the LMV861.  Is this violating the specs of this IC?

  • 0
    TI__Guru 54976 points

    Hello Kevin,

    You do not want to drive capacitance directly from the output to ground.

    But with AC coupling, you are usually going into a (hopefully) resistive load or high-impedance input of the next stage.

    The coupling capacitor looks like an AC short. As long as the load resistance that the output is looking into through the coupling capacitor is high enough (greater than the recommended Riso), it should not be a problem.

    Regards,

  • 0 in reply to Paul Grohe
    Intellectual 300 points
    Hello,
    In that case, I do not know where the oscillations in my signal chain could be coming from. Could I share the schematic with you offline? We are using two TI amps: LMV861 and OPA4322.