Differentiating amplifier responsive to track locations and variations of element values from desired values
AssigneeVTC Inc.
InventorsDavid E. Sutliff, Jeffrey A. Gleason
Life of this patent
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Abstract
An amplifier is compensated for variations in element values. A trim signal is generated based on element values of filter elements of a filter in the amplifier. An RC product in the amplifier is controlled based on the trim signal. The RC product corresponds to a product of a dynamic resistance value of a dynamic resistance element in the filter in the amplifier, and a capacitance value of capacitive elements in the filter. The RC product also determines a pole position of the amplifier. Gain in the amplifier is controlled based on the trim signal so that a desired gain is maintained.
Claims6
A variable bandwidth differentiating amplifier for a disk drive in which information is recorded in concentric tracks, the disk drive having a register containing an identification of the track from which information is being read, the amplifier comprising:
- a differential amplifier;
- a variable bandwidth filter operatively connected to the differential amplifier, the filter including;
- semiconductor means having a resistance value which varies with a bias current through the semiconductor means;
- and
- reactive means, having a reactive element value, connected to the semiconductor means;
- generating means for generating a trim signal based on variations of the resistance value and the reactive element value from desired values;
- and
- current source means, coupled to the semiconductor means, and responsive to the track identification in the register and responsive to the trim signal, for generating the bias current through the semiconductor means representative of the track from which information is being read, and representative of the trim signal.
Dependencies are inferred from the claim text.