Pipelined demodulation and adc conversion scheme for disk drive servo

Abstract

A servo system for controlling the position of a read/write head in a disk drive is provided. The servo system includes an input terminal for sequentially receiving a plurality of input signal bursts of a burst pattern, wherein the input signal bursts include positional information of the head. Demodulation circuitry, coupled to the input terminal, sequentially demodulates each input signal burst and provides a demodulated signal for each burst. An ADC, coupled to the demodulation circuitry, sequentially converts each demodulated signal. The ADC converts a first demodulated signal corresponding to the first of the plurality of input signal bursts before the demodulation circuitry completes demodulating the next of the plurality of input signal bursts. In a preferred embodiment, the ADC converts a demodulated signal corresponding to a first input signal burst while the demodulation circuitry demodulates a signal corresponding to a second, and subsequent, input signal burst. Thus, a pipelined demodulation and conversion scheme is disclosed in which time delays between demodulation and conversion are reduced. In the preferred embodiment, the demodulation circuitry includes area detect circuitry having an integration circuit and a single track-and-hold amplifier.