Texas Instruments Corporation

Seagate Technology Incorporated

Scott Gary Sorenson

Raymond Elijah Barnett

Tuan V Ngo

Jeremy Robert Kuehlwein

Marco Corsi

Rajarshi Mukhopadhyay

Paul Merle Emerson

Tuan Van Ngo

A method for calibrating a reflection compensator is provided. A delay is initially set to a predetermined minimum, and an input pulse is transmitted across a transmission line. A compensation current is then applied after the delay. The reflection from the transmission line is digitized to generate a measurement, and a determination is made as to whether the compensation current substantially compensates for the reflection. If the compensation current does not substantially compensate for the reflection, then the delay is adjusted, and the process is repeated until the compensation current substantially compensates for the reflection.

Method and apparatus for reflection cancellation

Methods and apparatus for generating a hard drive write signal are here in disclosed. A disclosed method comprises generating a hard drive write signal on an output of a switch based on an edge of the first control signal and reducing the hard drive write signal based on an edge of a second control signal via a second switch.

Methods and apparatus for generating a hard drive write signal

A write current circuit () adapted to drive a thin film write head () of a mass media information storage device. The write current circuit () further includes programming circuitry () driven such that parameters of the write current waveform can be varied, including the write current overshoot amplitude and/or overshoot duration. The present invention achieves technical advantages by providing the ability to program out or adjust for system introduced asymmetries in the write current waveform.

Write current waveform asymmetry compensation

A circuit () for use in a mass data storage device () has first () second () current driver circuits for providing write currents to the data transducer (). The first and second current levels are different, the second current level being lower than the first. The first current driver circuit () may be used to apply currents representing user data to the data transducer () and the second current driver circuit () may be used to apply currents representing servo information to the data transducer (). In addition, the first () and second () current drivers circuits may be operated at different frequencies. The first () and second () current driver circuits additionally may share at least some circuit components (--), and may operate at different write speeds.

Low power servo mode write driver

A write driver () produces balanced voltages across head () by using the input write data (WDX and WDY) drive transistors of a slower transistor type (typically PNP) on one half of an H-bridge configuration, while transistors of a faster transistor type (typically NPN) in the other half of the H-bridge configuration are driven indirectly by transistors of the slower type, with a trans-resistance in series with transistors of the faster type. Accordingly, the voltage nodes on either side of the write head are pulled to Vcc and Vee symmetrically. A trans-resistance block () uses current sources to pull current from capacitive nodes for faster switching.

Hi-speed preamplifier write driver for hard drive with improved symmetry

A write driver produces balanced voltages across head by using the input write data drive transistors of a slower transistor type (typically PNP) on one half of an H-bridge configuration, while transistors of a faster transistor type (typically NPN) in the other half of the H-bridge configuration are driven indirectly by transistors of the slower type, with a trans-resistance in series with transistors of the faster type. Accordingly, the voltage nodes on either side of the write head are pulled to Vcc and Vee symmetrically. A trans-resistance block () uses current sources to pull current from capacitive nodes for faster switching.

Hard disk storage system including a first transistor type and a second transistor type where a first voltage level pulls one of a first pair of transistors and a second voltage level pulls one of a second pair of transistors at substantially the same time

The present invention covers circuits to achieve high data rate writing.

Circuits to achieve high data rate writing on thin film transducer

A voltage-mode boosting write driver circuit () having a pair of voltage boosting PMOS transistor sets () coupled to a high current H-switch (). One set () of the boosting PMOS transistors correspondingly pulls output pin HY high, while the other transistor set () correspondingly pulls output pin HX high and the other output pin HY low thereby significantly improving the head voltage swing, and also achieving a faster slew rate. Moreover, resistors (R, R) of the H-switch are both matched to each other and impedance matched to a flex cable (T) interconnection impedance, which interconnection is coupled to the thin film head, to thereby eliminate signal reflection such that the write current (Iw) settles quickly with minimum ringing to achieve a high data rate. Moreover, less power dissipation and smaller number of devices used are achieved by making use of existing transient currents of the pre-driver emitter follower stage.

Method to increase head voltage swing and to reduce the rise time of write driver

A write current circuit ( ) adapted to drive a thin film write head (L ) of a mass media information storage device. The write current circuit includes a write current reference voltage circuit ( ) adapted to selectively establish amplitude of a write current signal. The write current circuit further includes programming circuitry (M -M ) driven such that several parameters of the write current waveform can be controlled, including the write current amplitude, overshoot amplitude and overshoot duration. The present invention achieves technical advantages by providing the ability to both produce an accurate write current, and also providing the ability to establish the write current waveform shape so that customers can optimize disk drive performance even when using different thin film write heads available from different suppliers.

Reference circuit for write driver circuit with programmable write current, overshoot duration and overshoot amplitude control

A write drive circuit ( ) for a hard disk drive selectively providing a current mode operation for high speed data write of a single channel, and selectively providing a voltage mode operation during a servo write operation. A central buffer has a first circuit ( ) providing a current mode drive signal to a head during a single channel write operation, and a second circuit ( ) providing a voltage mode drive signal for multi-channel servo write operation. The outputs of both circuits ( ) is provided over a common differential connection (T ) feeding a pre-driver circuit ( ) adapted to drive one or many heads, as determined by head select control lines ( ). The circuit provides >1.6 Gb/s data write speed in single channel write operation, and has an architecture utilizing only two signal lines for four channels.

Method to write servo on multi-channels with voltage mode data and single channel with current mode data

A disc drive includes a recording head preamplifier circuit having a plurality of preamplifiers. Each preamplifier includes a receiver circuit and a preamplifier enable circuit. The receiver circuit receives a serial command having command address bits. The preamplifier enable circuit is operatively coupled to the receiver circuit and generates an enable output for enabling the preamplifier when the command address bits match a first predetermined logic pattern which is unique to chat preamplifier and when the command address bits match a second predetermined logic pattern which is universal to the plurality of preamplifiers.

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Lakeville, MN, United States of America

Scott Gary Sorenson