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. 20, 1977
Filed:
May. 06, 1976
Jerome Danforth Harr, San Jose, CA (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
The ideal response expected of an electromagnetic transducer, particularly of the Magneto-Resistive (M-R) type, obtains with signal translating circuitry for amplifying the varying signal produced and for dynamically biasing the transducer for maintaining the transducing operation in the linear portions of the characteristics of both the transducer and the amplifying circuitry. An M-R transducer is connected to the input circuit of alternating signal differential amplifying circuitry for delivering the desired signal at output terminals. The offset voltage across the transducer is compensated by differentially biasing input transistors of the amplifying circuitry. Biasing direct current through and/or voltage across the M-R transducer is controlled by a circuit connected to the output terminal and responsive to the signal thereat for developing a slowly inversely varying unidirectional voltage, preferably within a low pass filter interposed in the control circuit for stability. A current handling device, conveniently a transistor having the control voltage applied to a base electrode, is connected in series with the transducer for dynamically adjusting the unidirectional biasing current flowing therethrough.