Amplifiers – Combined with automatic amplifier disabling switch means
Patent
1997-10-08
2000-08-29
Shingleton, Michael B
Amplifiers
Combined with automatic amplifier disabling switch means
330124D, 330124R, 330126, 330295, H03G 330
Patent
active
061114596
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a power amplifier and a communication unit which process signals; at least one of the frequencies, the output powers and the modulation types of which are different from each other; and more particularly relates to a power amplifier and a communication unit having at least one switch.
BACKGROUND ART
In recent years, various kinds of information communication units, such as cellular phone units and portable information terminals, have been developed or have just started to be commercialized all over the world. Each of these information communication units operates based on its unique system. Thus, the frequency bands, the output powers and the modulation types are different from each other among these systems. Consequently, transmission power amplifiers adapted for the respective systems have been developed and integrated into the terminals.
In Japan, two types of communication methods are utilized for automobile radiotelephone units and cellular phone units, i.e., an analog type FM (frequency modulation) type and a digital type .pi./4 shift DQPSK (differential quadrature phase shift keying) type. Both of the analog and the digital types are assigned to the frequency band of 800 MHz, while only the digital type is assigned to the 1.5 GHz band. Furthermore, a cellular phone called "PHS" (personal handy-phone system) is for a digital type .pi./4 shift DQPSK type and the 1.9 GHz band. The output power of automobile radiotelephone units and cellular phone units is on the order of 1 W, whereas that of cellular phones is on the order of 10 mW. Since the former phone units have a cell radius of several kilometers and a hand-over function, the phone units of the former type can be used for communication even during travel in an automobile or the like. On the other hand, the phone units of the latter type have a cell radius of several hundreds of meters and have been developed by such an approach as to utilize conventional indoor-use cordless phone units for outdoor use. Furthermore, though the 2.4 GHz band, i.e., the ISM (Industrial Scientific Medical) band, has been globally assigned to industrial, scientific and medical applications, it is also under consideration to apply the ISM band to wireless LANs (local area networks) within offices, factories or various kinds of sites in accordance with the spread spectrum (SS) type so as to comply with the standard in which the output power is 10 mW/MHz (frequency band: 26 MHz). As can be seen from these tendencies, information communication units, which can be used anywhere at any time, will surely be popular for use in daily life in the near future.
Conventionally, a transmission power amplifier satisfying the desired frequency band and the desired output power is integrated into the corresponding terminal depending upon which of these types the terminal is based on. Thus, a user has been required either to have terminals of different types corresponding to the domestic service areas and applications, or to buy an expensive, large-sized terminal compatible with several different types for itself.
FIG. 35 is a block diagram of a conventional example. This conventional example is a multi-stage power amplifier for transmitting two different radio frequency (RF) signals having different frequency bands and output powers, in which two banks of power amplifiers corresponding to the respective frequency bands are used.
A first power amplifier PA1 includes: a first input matching circuit PA104; a first GaAs MESFET PA101; a first inter-stage matching circuit PA105; a second GaAs MESFET PA102; a second inter-stage matching circuit PA106; a third GaAs MESFET PA103; and a first output matching circuit PA107.
A second power amplifier PA2 includes: a second input matching circuit PA204; a fourth GaAs MESFET PA201; a third inter-stage matching circuit PA205; a fifth GaAs MESFET PA202; a fourth inter-stage matching circuit PA206; a sixth GaAs MESFET PA203; and a second output matching circuit PA207.
The power amplifier of this conven
REFERENCES:
patent: 3304507 (1967-02-01), Weekes et al.
patent: 4494077 (1985-01-01), Fukaya et al.
patent: 4794347 (1988-12-01), Muramoto
International Search Report for Application No. PCT/JP96/02770; Mailed Jan. 28, 1997.
Search Report for Application No. 96931987.0-2215-JP9602770; Dated Oct. 22, 1988 (EPO).
Ishikawa Osamu
Kunihisa Taketo
Nishijima Masaaki
Matsushita Electric - Industrial Co., Ltd.
Shingleton Michael B
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