Sigma-delta modulation adaptive digital filter

A novel approach to the realization of an adaptive transversal filter without multipliers is presented. In the realization, a modified least-mean-square (LMS) algorithm is used for updating the filter coefficients. The input signal is encoded by a sigma-delta modulator, thus it eliminates the need for complicated analog-to-digital converters and requires no multipliers for any filter length. Computer simulations are included to confirm the convergence of the mean-squared error. Performances of the filter as adaptive noise canceller and adaptive line enhancer were also demonstrated by computer simulations.<>