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:
Oct. 26, 1999
Filed:
Aug. 08, 1997
Thomas Hornak, Portola Valley, CA (US);
Knud Knudsen, Menlo Park, CA (US);
Hewlett-Packard Company, Palo Alto, CA (US);
Abstract
An image-rejecting receiver comprises a tunable mixer stage, a time-share I-Q mixer stage, a complex filter, and an image rejector. The time-share I-Q mixer stage includes a switch assembly, inphase and quadrature polarity inverters, and a clock generator. The switch assembly generates pulses and distributes them in alternation to the polarity inverters. Performing distribution prior to polarity inversion preserves the orthogonality of the inphase and quadrature target signal components despite pulse-to-pulse bleeding. Charge accumulated at the distributor switch input is dumped between pulses to further minimize such bleeding. A current-mode field-effect-transistor implementation ensures unity gain across each polarity inverter so that they are gain-matched. Gain matching and preservation of orthogonality optimize the conditions for the complex filter to attenuate and for the image rejector to cancel an image signal. The polarity inverters are switched in quadrature to relax polarity-inverter transition timing tolerances, decreasing costs and increasing reliability.