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:
Mar. 23, 2004
Filed:
Nov. 13, 2000
Adrian J. Bergsma, Ottawa, CA;
Ronald Douglas Beards, Mountain, CA;
John Jackson Nisbet, Nepean, CA;
Theodore Gregory Carron, Kanata, CA;
Nortel Networks Limited, St. Laurent, CA;
Abstract
A method and system for reducing local oscillator leakage from radio frequency mixers is disclosed. Compensating circuits are used to reduce or eliminate unwanted leakage from the mixer output signal by controlling the current in individual branches of a balanced input circuit of the mixer. The current is directly controlled by adjusting the voltage on the bases of the differential type amplifier input transistors, or by injecting current directly into the individual branches, or by extracting current directly from the individual branches. The current is also indirectly controlled by increasing the temperature of the mixer components with power dissipation elements that are not connected to the mixer. The compensating circuits are made of different combinations of resistor, transistor and current sink components. By using the compensating circuits with a radio frequency mixer, any DC current differential occurring between two output nodes of the input circuit are reduced or eliminated, resulting in high quality signal transmissions.