240 MHz 8-tap programmable FIR filter for disk-drive read channels

Abstract

A 240 MHz digital FIR equalizer is presented for magnetic disk drive applications. The FIR has low latency to allow sufficient gain and stability in the channel timing and gain feedback loops. Programmable coefficients are supported so that the filter response can be modified in real time according to the demands of zone bit recording. Demands on accuracy as well as the number of taps vary, so the design is modular in the number of taps and bits to allow reuse in multiple applications.