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OPA2132: input impedance

Mia Ma
Intellectual 2345 points
Part Number: OPA2132

Hi team,

I am approaching to you for an curious question from customer side for OPA2132.

For OPA2132, the input impedance spec is as following:

Could you share some insights on how we test this input impedance spec?

Thanks

Best regards

Mia Ma

  • 0
    TI__Guru 63770 points

    Hi Mia,

    Below please find the explanation how to determine op amp's common-mode input resistance and input capacitance.

    Rin_cm = delta_Vcm / delta_IB - see below.

    Cin_cm is based on the -3dB roll-off where Cin-cm = 1 / (2*Pi*f*R1) - see below.

    The measurement of differential input impedance is much more involved and less consequential since in the linear operation input terminals are at the virtual short.