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:
Jul. 01, 2003
Filed:
Jun. 29, 1999
David Hoyt, Satellite Beach, FL (US);
Stuart W. Pullen, Raleigh, NC (US);
Patrick A. Begley, West Melbourne, FL (US);
Arecio A. Hernandez, Melbourne, FL (US);
Jeffrey M. Strang, Durham, NC (US);
Harris Corporation, Melbourne, FL (US);
Abstract
Pulse width modulated (“Class D”) amplifiers and controllers switching in the 50 khz to 2 MHz range generate harmonics which interfere with AM radio reception. This has precluded wide spread acceptance of class D amplifiers in products with an AM radio. The amplifiers described here use a modified modulation technique when operating with an AM radio to avoid generating harmonics at the receiver selected frequency or its intermediate (IF) frequency. One embodiment uses a harmonic avoidance modulator. A second embodiment uses two or more oscillators and tests for the least distorted output signal. A third embodiment switches the mode of operation to a class AB amplifier when an AM signal is amplified.