Analog Devices,inc.

Mairtin Walsh

Peter Real

Philip Eugene Quinlan

Kenneth T Deevy

Patrick Griffin

Jan Craninckx

Wim Dehaene

Michel Steyaert

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.

Pipelined demodulation and ADC conversion scheme for disk drive servo

A servo system for controlling the position of a read/write head in a disk drive is provided. The servo system includes two input terminals for sequentially receiving a plurality of input signal AC voltage bursts of a burst pattern, wherein the input signal bursts include positional information of the head. Demodulation circuitry, coupled to the input terminals, sequentially demodulates each input signal burst and provides a demodulated signal for each burst. The demodulation circuitry includes translation circuitry, coupled to the input, for sequentially translating each input voltage burst to a translated current. A rectifier circuit, coupled to the translation circuitry, including an absolute value circuit and a current mirror circuit, sequentially rectifies each translated current and produces a driving signal. An integrator, coupled to the rectifier circuit, sequentially integrates each driving signal. The integrator includes an integration capacitor which is sequentially charged by each driving signal. In the preferred embodiment, the current mirror circuit includes an operational amplifier and a gain circuit. Also in the preferred embodiment, the voltage to current translation circuit includes a folded cascode circuit arrangement of a plurality of CMOS transistors.

Rectifier and integrator circuit for disk drive servo system

Growing community of inventors

Limerick, Ireland

Mairtin Walsh