A simple continuous-time equalizer for use in magnetic storage read channels

A four-pole continuous-time equalizer has been developed to minimize the error rate in rigid-disk magnetic storage channels employing peak detection at high recording densities. The design process consisted of two parts. A nominal model of the disk drive characteristics in the time and frequency domains was obtained from digitized waveforms at the output of a read-head amplifier in a disk drive system. The relative performance of candidate equalizers was studied by subjecting them to the measured data waveforms and then either estimating or measuring the resulting bit error rate in a simulated peak detector, operating on the equalized waveforms. The equalizer outperforms more complex structures proposed for this task and is well suited for implementation as an analog CMOS active filter with low power dissipation. Its constellation of four poles and a zero appears to be useful for several types of magnetic media