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:
Apr. 21, 2009
Filed:
Aug. 25, 2006
Myron J. Koen, Tucson, AZ (US);
Myron J. Koen, Tucson, AZ (US);
Texas Instruments Incorporated, Dallas, TX (US);
Abstract
A circuit includes a first variable resistor having a resistance which is variable in response to a resistance control signal. A resistance control circuit includes a first current source circuit for supplying a first current through a reference resistor. A second current source circuit supplies a second current through the first variable resistor. In operational amplifier has a first input coupled to a first conductor connecting the first current source to the reference resistor, a second input coupled to a second conductor connecting the current source to the first variable resistor, and an output applying the first resistance control signal to a control terminal of the first variable resistor, to force the resistance of the first variable resistor to be equal to a resistance of the reference resistor. The resistance of a second variable resistor of an attenuator is controlled in response to the resistance control signal.