Read channel having auto-zeroing and offset compensation, and power-down between servo fields
US5648738A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 1, 1994 |
| Grant date | Jul 15, 1997 |
| Priority date | — |
| Expiry date | Nov 1, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B5/59627
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A read channel especially suited for disk drives, the read channel having auto-zeroing and offset compensation operative with sufficient speed to allow powering-down much of the read channel electronics between servo fields when a read operation is not being executed, is disclosed. Auto-zeroing is accomplished by temporarily shorting what would have been the signal received from a pre-amplifier, and charging capacitors in feedback loops temporarily switched in-circuit in the various circuits being auto-zeroed. After auto-zeroing, any remaining offset, including that imposed by an analog-to-digital converter converting the analog read signal to digitized samples of the read signal, is removed by filtering the digitized read signal samples by a digital filter acting as a low pass filter (integrator and lossy integrator in the embodiment disclosed), and reconverting the digital output of the filter to analog form for subtraction from the input to the analog-to-digital converter. Other aspects of the invention are also disclosed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.