Technique for fixing tap coefficients in a programmable finite-impulse-response equalizer

Abstract

A method for selecting which tap coefficients of a programmable finite-impulse-response (FIR) equalizer to fix includes performing an initial calibration to determine an initial value for each tap coefficient of a FIR equalizer. Using these initial values, a 'total' FIR equalizer is determined which sets the tap coefficients to their initial values. The method further determines multiple sets of tap coefficients that may potentially be fixed in the FIR equalizer. For each set of tap coefficients that may potentially be fixed, the method determines a 'fixed' FIR equalizer that sets the tap coefficients in the set to their initial values and other tap coefficients to zero. The method then determines a phase-difference energy between the “total” FIR equalizer and the “fixed” FIR equalizer for each set of tap coefficients that may potentially be fixed. The set of tap coefficients associated with the lowest phase-difference energy are then fixed.