Dell Products Inc.

Digital Equipment Corporation

Maxtor Corporation

Raymond Pavlak, Jr

Jingfeng Liu

Jason Pritchard

Lynn Lingyu Kong

Jinghuan Chen

A printed circuit board of an information handling system includes a dielectric layer, adjacent differential pairs, a ground layer, and a ground wall. The adjacent differential pairs are plated on the dielectric layer, and generate crosstalk between each other. The ground wall is in physical communication with and electrically coupled to the ground layer. The ground wall extends substantially perpendicular from the ground layer through the dielectric layer. A top surface of the ground wall is a specific height above a top surface of the adjacent different pairs. The ground wall suppresses the generated crosstalk based on the specific height and a width of the ground wall.

Crosstalk suppression microstrip line

Methods are disclosed for detecting a thermal asperity condition of a head that is configured to generate a read signal by reading data on a rotatable data storage disk in a disk drive. The read signal includes a data component and a thermal component. The read signal is compared to a thermal asperity threshold to detect occurrence of an excessive level of the thermal component of the read signal as a thermal asperity condition of the head. The thermal asperity threshold is varied in response to a rate of occurrence of data value transitions in the data component of the read signal. The thermal asperity threshold can be increased in response to a decrease in the rate of occurrence of data value transitions, and can be decreased in response to an increase in the rate of occurrence of data value transitions. By varying the thermal asperity threshold, the sensitivity of the thermal asperity detector may be improved to allow lower level thermal asperity conditions to be detected with increased accuracy. Related disk drives are also disclosed.

Detecting a thermal asperity condition of a disk drive head responsive to data value transitions

An optical angular position sensing system determines the angular position of a primary, beam-directing mirror by sensing the position of a beam from a secondary light source reflected from a secondary mirror on the back surface of the primary mirror. The position sensing system includes a photodetector that produces two output currents, the difference of which represents both the position of the reflected secondary beam and the intensity of the light source. A second servo-loop dynamically normalizes the output of the sensor by controlling the intensity of the light source to stabilize the total output of the sensor. The light source is oriented relative to the secondary mirror such that the mirror reflects a long dimension of a cross-section of the beam in a direction which is perpendicular to the direction of beam movement. The beam thus overlaps the transverse dimension of the photodetector so that maintenance of a predetermined light flux on the photodetector does not require precise placement of the light source or the sensor. To provide a low mass mirror, the primary mirror is formed on a silicon substrate and the secondary mirror is formed by adding a reflective coating to the back surface of the substrate. Forming the mirrors on two surfaces of the substrate also eliminates position errors related to differences in the relative positions of the two mirrors.

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Shrewsbury, MA, United States of America

Raymond Pavlak, Jr