DESIGN, IMPLEMENTATION AND PERFORMANCE EVALUATION OF AN MDFE READ CHANNEL

A 100 Mb/s (1,7) MDFE (multi-level decision feedback equalization) rea d channel has been designed, prototyped, and tested on a spinstand. It is made up of an analog forward equalizer consisting of two biquads, a comparator, a feedback equalizer consisting of 6 taps plus an analog exponential decay circuit, timing/gain/dc-offset control circuits, an analog PLL and VCO, and VGA. An analytical technique has been develop ed for equalizer design. It incorporates certain key constraints for r educing hardware complexity as well as error propagation. The measured bit-error-rate and off-track performance demonstrate the robustness o f the equalizer over a broad range of user densities. The experimental results confirm that MDFE is a viable signal detection technique for achieving high density and high data rate magnetic recording.