PROGRAMMABLE TIME-MULTIPLEXED SWITCHED-CAPACITOR VARIABLE EQUALIZER FOR ARBITRARY FREQUENCY-RESPONSE REALIZATIONS

A time-multiplexed digitally-programmable switched-capacitor (SC) vari able equalizer which allows the realization of arbitrary frequency res ponses is presented. The circuit performs the same operation as a casc ade of N second-order programmable equalizers, where N is also the mul tiplexing order, Except the storing capacitors, the rest of the circui try is shared for all individual equalizer functions (channels), resul ting in silicon area savings higher than 60% with respect to a direct circuit implementation for N = 4, The impact on circuit performance of crosstalk effects is discussed. Experimental results of a 3-V timesha ring SC equalizer architecture fabricated in a CMOS 1.2 mu m technolog y are given for different values of the multiplexing order. The circui t has been designed to be incorporated in a programmable hearing aid d evice.