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

摘要

Four test circuits for measuring operational amplifier common-mode rejection ratio (CMRR) are described and analysed. Sample results are presented for the /spl mu/A741, 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.