Optimum design and implementation of IIR SC filters using small-order FIR cells

Abstract

A novel approach for designing infinite impulse response (IIR) switched-capacitor filters, based on the optimum allocation of poles and zeros of a transfer function, implemented by a direct-form topology using finite-impulse response (FIR) cells as basic building blocks is presented. As a consequence, low sensitivity with respect to capacitance ratio errors in both passband and stopband frequencies, low power consumption, and improved group delay response are achieved. Comparisons with classical IIR and linear-phase FIR filter designs are made. An illustrative design example including simulation and experimental results obtained with a prototype filter are provided.Index Terms-Delay equalizers, direct form, pole and zero assignments, sensitivity, switched-capacitor filters.

A new delay line structure for switched capacitor (SC) circuits

“…An IIR low-pass filter is implemented for the specifications (coefficients) given in table 1 which corresponds to equation (2) [4]. The filter is implemented with five 2 nd order FIR cells.…”

“…The sampling frequency is J;=lkHz which is the same as [4]. Its transient analysis results are captured first, for each sine input signal with frequency sampled from 1Hz to 500Hz inclusive, and then the captured data undergo OFT analyses with Mat Lab.…”

“…3, and a higher order FIR filter can be realized with cascading 2 nd order FIR cells or implemented directly with a longer delay line. An IIR filter can be realized by two FIR filters, one in the forward path and the other in the feedback path [4]. The operation of Fig.…”