Agere Systems Inc.

Avago Technologies General IP (singapore) Pte. Ltd.

Lsi Corporation

Avago Technologies International Sales Pte. Limited

Jeffrey A Gleason

Ross Wilson

Scott O'Brien

Cameron Carroll Rabe

Scott M O'Brien

Jason P Brenden

Michael Straub

Paul Mazur

David Fitzgerald

Jaydip Bhaumik

Arvind Reddy Aemireddy

David W Kelly

Anamul Hoque

Bruce Alexander Wilson

Travis Roger Oenning

John D Leighton

Peter John Windler

Hao Fang

Jason S Goldberg

Robert Wimmer

Boris Livshitz

James Patrick Howley

Daniel J Dolan, Jr

Ronen Malka

Robert Alan Norman

Nameeta Krenz

Shubha Bommalingaiahnapallya

Paul Mark Mazur

Junqi Hua

A module including first and second variable inductances. The first variable inductance is electrically connected to a pair of nodes in a first half-circuit. One of the nodes in the first half-circuit is a first connection terminal. The second variable inductance is electrically connected to a pair of nodes in a second half-circuit. One of the nodes in the second half-circuit is a second connection terminal. The first half-circuit receives a flow of current in response to the second half-circuit supplying the current to the load in a flow direction from a load through the first connection terminal. The second half-circuit is configured to receive the flow of the current in response to the first half-circuit supplying the current to the load in a direction opposite to the flow direction from the load through the second connection terminal.

Switchable inductor for boost or matching optimization

A storage system includes a magnetic write head, a magnetic storage medium, a channel circuit comprising a write data output, wherein the channel circuit is operable to process write data to be recorded on the magnetic storage medium by the magnetic write head, and a preamplifier operable to receive the write data from the channel circuit, wherein the preamplifier comprises a number of register pages configured to store pattern dependent write current characteristics for a variety of magnet lengths, and wherein the preamplifier is operable to retrieve the write current characteristics based on magnet lengths and to record data bits on the magnetic storage medium using the write current characteristics.

Magnetic recording system using pattern dependent writer having register pages for storing write currents

An apparatus for two-dimensional magnetic recording includes a storage medium, an array of magnetoresistive read heads disposed adjacent the storage medium and spaced to read a data track, a number of leads connected to the array of magnetoresistive read heads, and number of bias circuits connected to the array of read heads by the leads. The bias circuits can be configured to independently bias each of the array of read heads with the array of read heads connected in series or in parallel.

Magnetoresistive reader for two-dimensional magnetic recording

An apparatus for two-dimensional magnetic recording includes an array reader with a number of magnetoresistive read sensors configured to read data from a storage medium. The magnetoresistive read sensors have a number of connection terminals, with at least one of the connection terminals being shared by more than one of the magnetoresistive read sensors. The apparatus also includes a number of low-noise amplifiers connected to the connection terminals, each configured to amplify a differential signal from a different one of the magnetoresistive read sensors. The apparatus also includes a number of impedance balancing networks connected to a subset of the connection terminals.

Preamplifier common-mode noise rejection for two-dimensional magnetic recording

An apparatus for correcting crosstalk in an array reader magnetic recording system includes an array reader comprising a number of read heads operable to read data from a magnetic storage medium, a preamplifier configured to amplify the signals from the read heads, and a crosstalk correction circuit configured to reduce crosstalk between signals from the read heads.

Preamplifier crosstalk correction in array reader magnetic recording system

An apparatus for two-dimensional magnetic recording includes a storage medium, an array of magnetoresistive read heads disposed adjacent the storage medium and spaced to read a data track, wherein the array of magnetoresistive read heads share a common terminal, a number of leads connected to the array of magnetoresistive read heads, with one lead for each of the magnetoresistive read heads, plus a common lead connected to the common terminal, wherein each of the plurality of leads other than the at least one common lead are referenced to the at least one common lead, and a preamplifier connected to the array of magnetoresistive read heads by the plurality of leads and operable to perform pseudo-differential sensing or single-ended sensing of signals from the array of magnetoresistive read heads.

Pseudo-differential shared-pin reader for two-dimensional magnetic recording

A hard disk drive or other disk-based storage device comprises a storage disk, a write head configured to write data to the disk, and control circuitry coupled to the write head. The control circuitry comprises a write driver and degauss circuitry associated with the write driver. The degauss circuitry is configured to generate a chirped degauss signal to be applied to the write head by the write driver. The degauss circuitry comprises a ramp generator configured to generate a ramp signal for controlling a frequency of at least a portion of a waveform of the chirped degauss signal. The ramp signal generated by the ramp generator may comprise a current ramp that is applied to a control input of a current controlled oscillator of the degauss circuitry.

Storage device having degauss circuitry with ramp generator for use in generating chirped degauss signal

A hard disk drive or other disk-based storage device comprises a storage disk, a read/write head configured to read data from and write data to the disk, and control circuitry coupled to or otherwise associated with the read/write head. The control circuitry comprises a write driver configured to generate a write signal for data to be written to the storage disk, and a multiple-slope transition controller associated with the write driver and configured to control a data transition in the write signal such that the data transition comprises at least two different segments each having a different slope, with the transition controller comprising separate slope control mechanisms for each of the segments. By way of example, the data transition may comprise a dual-slope transition having first and second segments arranged sequentially between a start point and an end point of the data transition.

Storage device having write signal with multiple-slope data transition

A voltage regulator, a method of regulating voltage and an IC including a voltage regulator. In one embodiment, the voltage regulator includes: (1) a DC precision amplifier configured to generate a DC precision signal based on a reference voltage and a regulated output of the voltage regulator and (2) a response amplifier, coupled in parallel with the DC precision amplifier, configured to generate an error signal based on the reference voltage and the regulated output, the response amplifier further configured to generate the regulated output based on a regulating signal comprised of the error signal and the DC precision signal. The DC precision amplifier may be a CMOS amplifier and the response amplifier may be a NPN amplifier.

Output compensated voltage regulator, an IC including the same and a method of providing a regulated voltage

Electronic circuitry and methods are disclosed for monitoring a portion of a write driver, for example, a steady state value of a write driver of a hard disk drive preamplifier. Based on a result of the monitoring, a condition, such as a fault, can be detected in the write driver. For example, apparatus for monitoring a write driver of a disk drive system comprises a comparator circuit coupled to an output of the write driver and configured to compare a value present at the output of the write driver with a reference value such that at least one condition associated with the write driver is detectable as a result of the comparison of the write driver output value and the reference value.

Write driver monitoring and detection

A recording system employing a magneto-resistive (MR) element senses a resistance value of the MR element and generates one or more MR resistance (MRR) signal values based on the sensed MR element resistance value. The MRR signal values might be, for example, current or voltage values proportional or inversely proportional to the MR element resistance value. The MRR signal values might be employed to control one or more of: i) a unity gain bandwidth of a bias loop for the MR element, ii) an MR read head preamplifier low corner frequency, and iii) a slew rate across the MR element.

Magneto-resistive head resistance sensor

An apparatus and method for determining a head parameter value (e.g., head resistance) of a resistive head. A test head current is supplied to the head during a head parameter measurement interval using the same current sources that supply a bias current to the head during an operating (read operation) interval. The determined head parameter value is latched for use in setting the control loop gain for a control loop that controls the current sources during the operating interval.

Method and apparatus for measuring resistance of a resistive sensor

An apparatus and method for determining a resistance of a magneto-resistive head. A current drawn by the head, in response to a fixed bias voltage across the head, is converted to a zero temperature coefficient current such that when supplied to a resistor connected to an input terminal of a comparator the effects of variations in the resistance value are avoided. An output signal of the comparator indicates the resistance of the magneto-resistive head.

Resistance mode comparator for determining head resistance

A method and apparatus for detecting signal peaks caused by a thermal asperity event in a magnetic recording media to reduce data reading errors introduced by the thermal asperity event. A common mode voltage is determined for differential signals representing data bits read from the magnetic recording media and a threshold voltage produced responsive to the common mode voltage. A comparator determines if either of the differential signals exceeds the threshold voltage, thereby indicating the occurrence of a thermal asperity event.

Variable threshold bipolar signal peak detector

A differential input/differential output converter circuit. The circuit comprises differential complementary input modules each comprising cross-coupled devices for biasing current mirror masters to a condition that increases the operating speed in response to a transition in the differential input signals. Certain current mirror masters are biased to a strong threshold condition and other current mirror masters are biased to a weak threshold condition responsive to a state of the differential input signals. According to another embodiment, the converter circuit further comprises a boost circuit capacitively coupled to the converter circuit for providing further speed improvements.

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Burnsville, MN, United States of America

Jeffrey A Gleason