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. 27, 2009
Filed:
Aug. 03, 2007
Hee Wong, San Jose, CA (US);
Michael Schwartz, San Jose, CA (US);
James Braatz, Kent, WA (US);
Shu-ing Ju, Palo Alto, CA (US);
Hee Wong, San Jose, CA (US);
Michael Schwartz, San Jose, CA (US);
James Braatz, Kent, WA (US);
Shu-Ing Ju, Palo Alto, CA (US);
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
Rejection of local oscillator harmonic response is provided in a mixing circuit with a pair of harmonic gating switches serially connected to the outputs of a balanced differential switching mixer and controlled by a gate clock signal having twice the frequency of a local oscillator signal controlling the switching mixer. An aperture or duty cycle of the gate clock signal determines which harmonic is rejected or suppressed, which is preferably a third and/or fifth harmonic since response of the balanced differential switching mixer to even harmonics is negligible. The resulting simple, efficient circuit is readily integrated directly into a phase-alternating mixer structure for a chopper-direct-conversion radio.