A digitally programmable IIR switched-capacitor filter for CMOS technology

This paper presents a novel procedure for the implementation of digitally programmable switched-capacitor recursive (IIR) filters. The use of transfer functions with a number of poles smaller than the number of zeros ensures low passband sensitivity, comparable to what is usually obtained with ladder structures implementing elliptic approximations. A digital-to-analog conversion technique allows filter programmability by controlling capacitor charge instead of a capacitor bank, saving both silicon area and power consumption. Further reduction in power consumption is achieved by multiplexing operational amplifiers to realize second-order FIR sections. Simulations considering a CMOS process are presented to verify the feasibility of the proposed approach in integrated circuit designs