The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 12, 1995
Filed:
May. 19, 1993
Krishnaswamy Nagaraj, Wescosville, PA (US);
Reza S Shariatdoust, Califon, NJ (US);
American Telephone and Telegraph Company, New York, NY (US);
Abstract
A demodulator circuit receives an input signal read from a track of a magnetic medium and generates a control signal to maintain alignment of a read-write head with the track. The demodulator circuit includes at least one transistor. The at least one transistor has an electrode switchable between first and second voltage sources. The electrode is coupled to the second voltage source to block processing of the input signal. The electrode is coupled to the first voltage source to process the input signal. The at least one transistor provides an effective resistance when coupled to the first voltage source that is dependent on the voltage level of the first voltage source. The at least one transistor half-wave rectifies the input signal when the electrode is coupled to the first voltage source. In this manner, the at least one transistor provides an effective resistance when the electrode is coupled to the first voltage source, the magnitude of the effective resistance being determined by the voltage level of the first voltage source, half-wave rectifies the input signal, and simultaneously selects that portion of the input signal to rectify. Disk drive systems that utilize this technique have the advantage of at least one transistor simultaneously selecting the number of pulses to be integrated when turned on and blocking integration of the input signal when turned off, controlling the gain of an integrator by varying the resistance when turned on, and half-wave rectifying the incoming signal to vary the automatic gain control.