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:
Nov. 18, 2003
Filed:
Jul. 30, 2001
Brian Taylor Brunn, Lakeville, MN (US);
Ramesh Harjani, Minneapolis, MN (US);
Xilinx, Inc., San Jose, CA (US);
Abstract
Many electronic devices, such as computers and printers, communicate data to each other over wireline or wireless communications links. One component vital to such communications is a voltage-controlled oscillator (VCO)—a circuit that outputs an oscillating signal having an oscillation frequency based on a control voltage. Conventional VCOs adjust frequency based on a single control voltage input, which makes them vulnerable to unintended changes in the control voltage (and power-supply voltages relative to the control voltage.) These voltage changes cause frequency deviations that can make communications between devices less reliable. Accordingly, the present inventors devised a VCO that includes differential frequency control—frequency control based on the difference of two control voltages. The VCO, which uses a differentially tunable impedance, rejects common-mode noise (undesirable voltage variations that affect both control voltages) and thus bolsters reliability of communication circuits, such as phase-lock loops, receivers, transmitters, transceivers, and other devices that use it