An Experimental MDFE Detector

A 100 Mb/s experimental multilevel Decision Feedback Equalization read channel has been designed and prototyped in discrete-components. The analog forward equalizer consists of two bi-quads, based on the maximization of inner eye versus noise power plus uncancelled ISI at the input to the detector. The feedback equalizer consists of a 6-tap filter plus an RC exponential decay network which helps reduce hardware complexity. The digitally implemented timing/gain/dc-offset loops are adjusted only when there are transitions. Bench testing shows that the error rate performance is about 1.5 dB away from the theoretically designed performance at user density 2.0.