szepesi@fluke.UUCP (Les Szepesi) (05/08/86)
I need to measure the ac common mode error of a wideband amplifier as a function of both amplitude and frequency. I have used servo-loop test circuits (similar to the one described in the Analog Devices application note "How to Test Basic Operational Amplifier Parameters") to measure CME at dc. However, the integrator used in this method makes it impractical for ac measurements. What I am looking for is a way to do this without having to have highly matched ac attenuators which would be required for a measurement in a differental configuration. (.1% mismatch ~= 60dB >> expected CMRR) I presume there is a convenient way to do this, since many op amp spec sheets have plots of CMRR vs. frequency. Thanks in advance. -- Les Szepesi decvax\ John Fluke Mfg Co. ihnp4 >!uw-beaver\ PO Box C9090 MS 274G allegra >!fluke!szepesi Everett, WA 98206 USA ucbvax >!lbl-csam / (206) 356-6362 hplabs/