Effects of the op amp finite gain and bandwidth on the performance of switched-capacitor filters

Abstract

A pair of complementary strays-insensitive switched-capacitor (SC) integrator circuits are analyzed to determine the errors in their transfer functions due to the finite gain and finite bandwidth of the op amp. The results are used to predict the transfer function deviation of biquadratic filter sections and LC ladder simulations. It is shown that while the effect of finite op amp gain is similar to that encountered in active-RC filters, SC filters are much more tolerant of the finite op amp bandwidth. However, the relationship between transfer function error and finite op amp bandwidth is an exponential one as contrasted to the linear relationship of active-R C filters. Experimental results are presented.