Amplifiers – With semiconductor amplifying device – Including frequency-responsive means in the signal...
Reexamination Certificate
2000-05-01
2001-04-10
Mottola, Steven J. (Department: 2817)
Amplifiers
With semiconductor amplifying device
Including frequency-responsive means in the signal...
C330S310000, C330S145000
Reexamination Certificate
active
06215359
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to dual band communication systems, and more particularly to impedance matching circuits for a power amplifier in a dual band transmitter.
BACKGROUND OF THE INVENTION
A dual mode transmitter can operate using two different systems. For example, an AM/FM dual mode transmitter can transmit both amplitude modulated and frequency modulated signals. For radiotelephones, a dual band transmitter can operate using two different cellular telephone systems. For example, a dual band GSM/DCS radiotelephone can use the Global System for Mobile Communications (GSM), which operates at 900 MHz, and the Digital Communications System (DCS), which is similar to GSM except that it operates at 1800 MHz.
In any radiotelephone, the power amplifier at the final stage of the transmitter should be matched to the impedance of the antenna. Additionally, harmonics of the transmitted frequency band should be suppressed to reduce interference with other communication systems operating at the harmonic frequencies. With a GSM/DCS dual band transmitter, it is difficult to suppress the first (1800) MHz harmonic during 900 MHz GSM transmissions and yet pass the 1800 MHz signal during DCS transmissions. Also the output impedance of a radiotelephone power amplifier should be matched to the antenna so that the impedance at the output of the amplifier is at the optimum impedance for power efficient amplification.
Thus, there is a need for a dual band power amplifier that can suppress harmonic frequencies during a first mode of transmission and also properly pass signals during a second mode of transmission, even when the signals of the second transmission are at or near a harmonic frequency of the first mode of transmission. There is also a need for a dual mode power amplifier with a limited number of parts and a low current drain.
REFERENCES:
patent: 4723306 (1988-02-01), Fuenfgelder et al.
patent: 4959873 (1990-09-01), Flynn et al.
patent: 5060294 (1991-10-01), Schwent et al.
patent: 5361403 (1994-11-01), Dent
patent: 5392463 (1995-02-01), Yamada
patent: 5406224 (1995-04-01), Mikami et al.
patent: 5423074 (1995-06-01), Dent
patent: 5432473 (1995-07-01), Mattila et al.
patent: 5455968 (1995-10-01), Pham
patent: 5530923 (1996-06-01), Heinonen et al.
patent: 5532646 (1996-07-01), Aihara
patent: 5748042 (1998-05-01), Norris et al.
patent: 5774017 (1998-06-01), Adar
patent: 6043721 (2000-03-01), Nagode et al.
patent: 6078794 (2000-06-01), Peckham et al.
patent: 6133793 (2000-10-01), Lau et al.
patent: 0 459 440 B1 (1996-09-01), None
patent: 2 236 028 (1991-03-01), None
patent: 2 260 871 (1993-04-01), None
Black Gregory Redmond
Peckham David Sutherland
Bowler II Roland K.
Chen Sylvia
Motorola Inc.
Mottola Steven J.
LandOfFree
Impedance matching for a dual band power amplifier does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Impedance matching for a dual band power amplifier, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Impedance matching for a dual band power amplifier will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2521427