Hewlett-packard Company

Agilent Technologies, Inc.

Philips Electronics N.v.

Bradley K Davis

Robert M Thelen

Johannes O Voorman

Derek L Knee

Michael Clinton Allyn

Joao N Ramalho

Patrice Gamand

In accordance with the present invention, a magneto-resistive head read amplifier circuit is provided which can be incorporated into a magnetic reader for reading information stored in magnetic form on a storage medium. The magneto-resistive head read amplifier of the present invention incorporates an inductor in the bottom current drain of the head read amplifier circuit which reduces or eliminates noise generated by the bottom current source transistor of the head read amplifier circuit. In accordance with a first embodiment of the present invention, the magneto-resistive head read amplifier is a single-polarity head read amplifier circuit which utilizes a bias current having a particular polarity. In accordance with a second embodiment of the present invention, the magneto-resistive head read amplifier is a dual-polarity head read amplifier circuit capable of operating with bias currents of opposite polarity. Both embodiments of the present invention preferably utilize a common mode feedback circuit and a differential feedback circuit which set the operating point of the head read amplifier circuits. The differential feedback circuit nulls the differential output voltage of the head read amplifier circuit and the common mode feedback circuit sets the minimum bias current for the magneto resistor. In the dual-polarity head read amplifier circuit, switching logic is utilized to enable the polarity of the bias current to selected.

Magneto-resistive head read amplifier

The present invention provides a write driver circuit for use in a magnetic read/write system for writing information to a magnetic storage medium. In accordance with a first embodiment of the present invention, the write driver circuit comprises a variable common mode circuit component for enabling the common mode output voltage of the write driver circuit to be varied and/or set to a preselected value. In accordance with a second embodiment of the present invention, the write driver circuit comprises a variable damping resistance circuit component for enabling the damping resistance of the write driver circuit to be varied and/or set to a preselected value in order to optimize write current rise time and overshoot. The write driver circuit may comprise both the variable common mode circuit component and the variable damping resistance component to enable both the common mode output voltage and the damping resistance to be varied and set to preselected values in order to optimize the performance of the write driver circuit. In accordance with another embodiment of the present invention, a relatively high-power write driver circuit is fabricated using a fabrication process normally used for fabricating relatively low-power write driver circuits. in accordance with this embodiment, the current sources of the write driver circuit are each comprised of a plurality of transistors connected in series in cascode configurations such that the voltage drop across any one of the transistors of the cascode configurations is limited to meet the requirements. of the fabrication process.

Programmable write driver circuit for writing information to a magnetic storage media

A scanning mouse has two optical navigation sensors to allow measurement of both translation and rotation of the scanning mouse. It also has an image sensor, and the ability to digitize the sensed image data. There may be a second image sensor at perpendicular to the first. A high speed digital data path connects the scanning mouse to the computer. Software in the computer processes image line data that includes the locations of the navigation sensors and the digitized image data to produce partial scanned images that are further assembled into a complete image within the environment of the computer. Each optical navigation sensor images as an array of pixels the spatial features of generally any micro textured or micro detailed work surface below the mouse. The photo detector responses are digitized and stored as a frame into memory. Motion produces successive frames of translated patterns of pixel information, which are compared by autocorrelation to ascertain the direction and amount of movement. A hold feature suspends the production of movement signals to the computer.

Scanning mouse for a computer system

A preamplifier circuit for a computer data storage system disk drive read/write head (or HSA) includes multiple test modes to enable electrical testing of the preamplifier, the read/write heads, and associated circuitry without physically probing the components or circuitry. Communication between the preamplifier and a host controller provides for test mode selection and test mode enablement within the preamplifier. Testing occurs using only the normal interface connector to the head disk assembly (HDA) in which the preamplifier and HSA are embodied. Properties such as electrical resistance, ESD, preamplifier bond wire connection integrity, head bond wire and solder joint integrity, and connections from the head slider to the preamplifier leads are all tested. Testing occurs without probing to provide efficient, reliable, and cost effective manufacturing and testing benefits of the read/write heads, flex assembly, HSA, and HDA.

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Ft. Collins, CO, United States of America

Bradley K Davis