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LMP7701: plot in PSpice impedance vs frequency

Marvin Cantos
Expert 5395 points
Part Number: LMP7701
Other Parts Discussed in Thread: TINA-TI

Hi Team, 

Good day. I am posting this inquiry on behalf of our customer.

"I am using Pspice. I want to plot the input and output impedance of opamp. I have connected one AC source to the opamp. How to plot in PSpice impedance vs frequency

I have added bootstrapping at the input of Opamp."

Please help to advise. Thank you for extending your support.

Kind regards, 

Marvin

  • 0
    TI__Guru 64600 points

    Hi Marvin,

    The resistive part of the LMP7701 input impedance, Rin, may be calculated under different conditions from the graphs of the change of the IB vs Vcm - see 11Tohm example below.

    The LMP7701 input common-mode capacitance (Cin_cm) may be simulated and then back-calculated as shown below to be 2.5pF.

    The output impedance (Zo) may be simulated as shown below.

    Below I have attached Tina-TI simulation files for your convenience.

    LMP7701 Rin_cm.TSC

    LMP7701 Zo.TSC