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Calculation for CMRR, PSRR and Temperature drift on Opamp LMV324

Sivaraman Radhakrishnan
Prodigy 130 points

Hi,

Can you help on calculation for CMRR, PSRR and Average temperature drift on the offset voltage.

Temperature at 40'C. 5V opamp supply has +/-1% tolerance.

Schemtics definition:

1.5V reference given to non-inverting terminal.

1 to 3V given to inverting terminal with 220K Ohm (input resistance).

220K Ohm Feedback resistance connected with inverting and output terminals.

Please help on the calculating the CMRR, PSRR and Temperature drift.

Thanks,

Siva

  • 0
    TI__Intellectual 1190 points
    Hello,

    Please refer to this app note that explains how to make these measurements pretty well. --> www.ti.com/.../sloa083.pdf

    In short, I would take an initial offset measurement with the opamp biased at a DC condition that is within the specified common mode range. Use that value as your reference for all of your measurements.

    Now, for CMRR, sweep the common mode range across the cared about region and measure the change in offset voltage from your reference.

    Same thing for PSRR, but sweep the power supply.

    For temp drift, use the datasheet data or sweep the temperature and measure the change in offset.

    Thanks,
    Andrew