Cirrus Logic Inc.

Silicon Laboratories Inc.

Tyson Tuttle

William G Bliss

Richard T Behrens

Trent O Dudley

David R Welland

Christopher P Zook

David E Reed

Paul M Romano

Diwakar Vishakhadatta

Jerrel P Hein

Aslamali A Rafi

Alessandro Piovaccari

Peter Vancorenland

Kent D Anderson

In one embodiment, the present invention includes a mixer circuit to receive and generate a mixed signal from a radio frequency (RF) signal and a master clock signal, a switch stage coupled to an output of the mixer circuit to rotatingly switch the mixed signal to multiple gain stages coupled to the switch stage, and a combiner to combine an output of the gain stages.

Rotating harmonic rejection mixer

A sampled amplitude read channel incorporated within a magnetic disk storage system for reading data recorded tracks on a magnetic medium, where the data comprises user data sectors recorded at varying data rates across a plurality of predefined zones and embedded servo data sectors recorded at the same data rate across the zones. The read channel comprises a timing recovery component for synchronous sampling of a read signal from a magnetic read head positioned over the magnetic medium, a gain control component for adjusting the amplitude of the read signal, and a DC offset component for canceling a DC offset in the read signal. These components are dynamically configured to operate according to whether the read channel is processing user data or embedded servo data.

Sampled amplitude read channel employing pipelined reads to reduce the gap between sectors

A sampled amplitude read channel is disclosed for reading data recorded on a disk storage medium by detecting an estimated binary sequence from a sequence of discrete time sample values generated by sampling pulses in an analog read signal from a read head positioned over the disk storage medium. The read channel comprises a sampling device, such as an analog-to-digital converter (A/D), for sampling the analog read signal to generate the discrete time sample values and for sampling at least one other auxillary analog input signal, such as a servo control signal. In this manner, performance characteristics of the read channel can be measured, such as the driving current applied to the servo control voice coil motor (VCM), without requiring additional hardware.

Sampled amplitude read channel for reading user data and embedded servo

A method and apparatus for calibrating an analog equalizer in a sampled amplitude read channel is disclosed wherein the filter's frequency response is measured and calibrated directly. This is accomplished by injecting a known periodic signal into the analog filter and measuring a spectrum value at a predetermined frequency. The filter parameters are adjusted accordingly until the spectrum reaches a predetermined target value. In the preferred embodiment, the analog filter comprises at least one second order low pass filter (referred to as a biquad filter), and the filter's spectrum is adjusted relative to the well known parameters f.sub.o and Q. Specifically, the parameters f.sub.o and Q are optimized relative to a power measurement at predetermined harmonics of the input signal. In this manner, the present invention enables auto-calibration of the analog equalizer without reading any data from the disc. Furthermore, the calibration process can be executed during the storage system's normal operation without significantly degrading its overall performance.

Method and apparatus for calibrating an analog filter in a sampled

A sampled amplitude read channel incorporated within a magnetic disk storage system for reading data recorded in concentric tracks on a magnetic medium, where the data comprises user data sectors recorded at varying data rates across a plurality of predefined zones and embedded servo data sectors recorded at the same data rate across the zones. The sampled amplitude read channel comprises a timing recovery component for synchronous sampling of a read signal from a magnetic read head positioned over the magnetic medium, a gain control component for adjusting the amplitude of the read signal, and a DC offset component for cancelling a DC offset in the read signal. These components are dynamically configured to operate according to whether the read channel is processing user data or embedded servo data. A user data frequency synthesizer and a servo data frequency synthesizer lock the timing recovery component to a reference frequency and provide a coarse center frequency control signal corresponding to the user data or servo data mode. The read channel further employs pipelined reads to reduce the physical gap between sectors on the medium. In addition, an improved sync mark detector and an improved asynchronous servo address mark detector increase the accuracy and reliability of the read channel.

Sampled amplitude read channel employing a user data frequency

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Austin, TX, United States of America

Tyson Tuttle