International Business Machines Corporation

Maxtor Corporation

Ching-Tzuen Tarn

Michael Anthony Moser

Stanley H Shepherd

Yakov M Lifchits

Tor W Moksvold

Colleen M Snavely

Mohamad A Rezvani

John Altieri

A spindle motor control for a disk drive including a spindle motor for rotating a data disk at a desired rotational speed, and a data transducer head positionable relative to selected ones of a multiplicity of concentric data tracks formed on a data storage surface of the data disk by a head position actuator structure operating within a head position servo loop, wherein the concentric data tracks are periodically interrupted by a plurality of servo sectors per rotation, each servo sector recorded with head position information. The spindle motor control includes: a servo detector for detecting the head position information in at least one servo sector on a selected track under the transducer head in relation to a timing signal at a reference frequency; a position detector for determining the circumferential position of the detected head position information on the selected track in relation to the timing signal; and a controller for controlling the rotational speed of the spindle motor as a function of said circumferential position, to regulate the circumferential position of the transducer in relation to the servo sectors on the data tracks.

Disk drive spindle motor speed and timing control

A lateral PNP bipolar transistor includes concentric circular emitter and annular base and dual collector regions. The inner collector region is moderately doped to provide good punch-through and Early voltage performance. The outer collector region is highly doped to provide low collector series resistance. A composite transistor made up of any desired number of individual transistors provides a transistor having a desired current capacity. The transistor annular base cross-section permits very accurate base width control during the manufacturing process.

Method for forming a lateral bipolar transistor with dual collector,

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San Jose, CA, United States of America

Ching-Tzuen Tarn