New approaches to measurement of operational amplifier common-mode rejection ratio in the frequency domain

Authors:
  • DFD.J. Faulkner
    D.J. Faulkner
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Abstract
Four test circuits for measuring operational amplifier common-mode rejection ratio (CMRR) are described and analysed. Sample results are presented for the µA741, characterising the variation of CMRR with frequency. Two new test circuits and a variation on an existing technique offer significant improvements over previous methods and are capable of accurate measurements on high-performance operational amplifiers.