ADAPTIVE SWITCHED-CAPACITOR FILTERS BASED ON THE LMS ALGORITHM

The implementation of adaptive FIR filters based on the LMS algorithm using SC circuits is described. The filters consist of the basic eleme nts: delay element, summing circuit, integrator, and multiplier. In an error analysis, the influence of nonideal effects of SC networks on t he behavior of a given filter is investigated. It is shown that the no nidealities in the FIR filter pert of the circuit can be eliminated by an additional constant tap element, whereas the main error source in the adaptation part are the multiplier- and integrator offset-errors, which can be compensated using special offset-free circuits. Using the proposed offset-compensation schemes, the accuracy of a switched-capa citor adaptive filter is mainly determined by the nonlinearity errors of the multipliers.