Direct-form SC filters with low frequency response sensitivity to the transfer function coefficients

The inclusion of mutually canceling pole-zero pairs in transfer functions having denominator order smaller than numerator order, to achieve low sensitivity of IIR direct-form SC filters to coefficient variations, is studied. Comparisons with the conventional elliptic SC filter design are shown to verify the effectiveness of the proposed approach. Monte Carlo analysis and Spice simulations carried out on a prototype filter designed in a 0.35-mum CMOS technology are presented to validate the theory.