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:
Aug. 13, 1996
Filed:
Mar. 10, 1995
Haruhiko Koizumi, Osaka, JP;
Akihisa Sugimura, Osaka, JP;
Kazuki Tateoka, Osaka, JP;
Kunihiko Kanazawa, Kyoto, JP;
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
In a dual-mode radio telephone transmitter operative in both an analog modulation mode based on the FDMA system and a digital modulation mode based on the TDMA system, a DC bias voltage Vdd to be applied to a power amplification circuit is varied in accordance with the type of modulation, so that the input/output characteristics of the power amplification circuit can be optimized. To this end, a micro processor controls a switch interposed between the power amplification circuit and a positive DC power unit in such a manner that the DC bias voltage Vdd is 4.8 V for the FDMA mode, while the DC bias voltage Vdd is 6.0 V for the TDMA mode. The value of another DC bias voltage Vgg in the power amplification circuit is fixed. The value of the DC bias voltage Vdd is set higher in the TDMA mode than in the FDMA mode; thus, it becomes possible to increase the power added efficiency in the FDMA mode, without adversely affecting high linearity and high efficiency in the TDMA mode.