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:
Jan. 11, 1983
Filed:
Jun. 30, 1980
Robert M Evans, Ringoes, NJ (US);
Other;
Abstract
A multiplexing arrangement enables a plurality of control voltages for controlling respective ones of a plurality of varactor controlled tunable filters, employed, e.g., prior to the tuner of a television receiver to reject undesired signals, to be generated by a single digital to analog (D/A) converter. A controller, which may, e.g., comprise a microcomputer, sequentially applies digital control words to the D/A converter and substantially synchronously causes the resultant control voltages generated by the D/A converter to be applied, through respective switches to the tunable filters. The control voltages are applied to capacitors connected to d.c. control lines for the tunable filters. The high impedance of the varactor diodes included in the filters enables the capacitors to store respective control voltages for relatively long intervals before the control voltages need to be refreshed. This enables a large number of tunable filters to be controlled by a single D/A converter.