A 15MHz CMOS Continuous-time Bessel Filter For Disk Drives

The primary function of the filter in disk-drive read channels is to bandlimit the noise at the output of the magnetic read head amplifier. The fifth-order 15MHz lowpass Bessel filter described here accommodates data rates up to 24Mb/s and is tunable from 6 to 15MHz for compatibility with the variable data rates used in constant-density recording disk drives. The filter is implemented with 5V 0.9µm CMOS continuous-time transconductance-capacitance circuit and achieves higherfrequency operation than recent approaches while minimizing power dissipation.