Parallel Circuit Architec tures for Imt)lementations of Monolithic Analog and Digital Equalizers for PRML Magnetic Disk Read Channels

Introductioq Sampled-data techniques such as Class IV PRML are becoming prevalent in channel implementations as the thrust continues toward higher data rates and recording densities. A key function required in the signal path of read channels employing sampled-data techniques is equalization which reduces the effects of intersymbol interference or ISI. At recording densities used in present drives, varying degrees of equalization are required depending on transition densities and signalling techniques. Programmable, fixed, and adaptive transversal filters have been shown to be effective in performing the equalization function for channels employing PRML signalling. In this paper, we will describe a fully parallel approach to transversal filter implementation which has been applied to both the analog and digital domain. There are specific implementation advantages to both which will be highlighted with a common advantage being that it allows the implementation of robust filters with speeds higher than otherwise possible using conventional filtering approaches.