Effects of coefficient inaccuracy in switched-capacitor transversal filters

Coefficient inaccuracy effects in the frequency response of finite-impulse-response (FIR) switched-capacitor filters implemented in direct form are investigated. No assumption is made with respect to the filter coefficients, so that the results of the analysis are valid for both linear and nonlinear phase FIR filters. Assuming that the errors in the capacitor ratios realizing the tap coefficients are uncorrelated and have identical Gaussian distributions, an exact probability distribution function is derived for the error in the frequency response. It is shown that this distribution can be characterized by a Rayleigh distribution, which is then used to derive an upper bound for the expected stopband attenuation. Extensive simulation results are shown to support the analysis. >