What can be the experimental test set-up to calculate CMRR of an analog circuit DUT

  1. Msmatrixin
    For any analog circuit which I would design, how should I measure the CMRR using lab instruments ?
  2. dick_freebird
    dick_freebird
    Get yourself an op amp test loop setup, like the ones shown here:

    http://www.analog.com/en/analog-dial...surements.html

    Then leave the common mode of the signal alone and vary the
    positive and negative supplies pairwise (so that your signal path
    remains ground referred for range / resolution), but its common
    mode position relative to the rails, moves.

    Depending on internal complexity, there could be a common mode
    w.r.t. ground sensitivity as well as an outer-rails sensitivity (classic
    op amps had no ground connection but more integrated lineups
    maybe have ground referred dividers, summing, filtering, etc.).
  3. Msmatrixin
    Msmatrixin
    Thanks .... quite helpful
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