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:
May. 20, 2003
Filed:
Feb. 21, 2002
David R. Pehlke, Chapel Hill, NC (US);
Aristotele Hadjichristos, Apex, NC (US);
William O. Camp, Jr., Chapel Hill, NC (US);
Ericsson Inc., Research Triangle Park, NC (US);
Abstract
An amplitude modulation circuit (modulator) provides modulated supply current, possibly in combination with modulated supply voltage, to a radio frequency (RF) power amplifier (PA), and includes a detection circuit responsive to changes in the ratio of that voltage to the modulated supply current, described herein as its AM modulation impedance. Such impedance (resistance) changes commonly arise from changing coupling characteristics at the RF antenna assembly driven by the PA. A gain control circuit may be associated with the detection circuit, and made responsive thereto, thus allowing adjustment of modulation gain control responsive to changes in PA AM modulation impedance. In one embodiment, this arrangement permits the modulator to hold a fixed modulation gain over changing PA AM modulation impedance, while in other embodiments, modulation gain varies in response to PA impedance changes to avoid signal clipping. Such clipping might otherwise occur where current modulation values in combination with increased PA resistance would result in PA voltages exceeding the supply voltage of the PA.