Amplifiers – With semiconductor amplifying device – Including frequency-responsive means in the signal...
Reexamination Certificate
2000-10-25
2002-05-07
Pascal, Robert (Department: 2817)
Amplifiers
With semiconductor amplifying device
Including frequency-responsive means in the signal...
C330S306000, C330S310000
Reexamination Certificate
active
06384688
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a high-frequency power amplifier module for amplifying high-frequency signal and particularly to a high-frequency power amplifier module that may be used suitably to a dual-band system radio equipment that can transmit and receive a couple of band frequencies.
BACKGROUND ART
In the European digital cellular system that is now put into the service as the mobile communication system, it is assumed in the GSM (Global System for Mobile Communication) using the frequency of 0.9 GHz band that subscribers will exceed the system capacity in near future. Therefore, the mobile telephone apparatus (hand-held telephone) corresponding to the dual-band system using, in combination with the GSM system, the DCS (Digital Cellular System) 1800 system using the frequency band near 1.8 GHz is requested because this system is similar to the GSM communication system in such a point that the same modulation system GMSK (Gaussian-filtered Minimum Shift Keying) is introduced.
Here, since above two systems (GSM system and DCS1800 system) are almost used in common except for the frequency, it is possible to structure the hand-held telephone set that is used in common in the GSM/DCS1800 systems by providing only the high frequency unit such as the power amplifier module that can be used for dual band system.
Therefore, in order to achieve the power amplifier module corresponding to the dual-band system, two power amplifier module systems corresponding to each communication system are integrated within the module and are structured to selectively switch each system as required.
FIG. 7
illustrates a schematic structure of the mobile telephone apparatus discussed prior to the present invention. In the same figure, a reference numeral
13
designates a blanching filter;
14
, a dual-band transmitting/receiving antenna;
15
, a first radio frequency power amplifier module (RF power module) ;
16
, a second RF power module;
17
, a wide-band amplifier (WAMP);
18
, a radio frequency signal processing unit (RFSPU) ;
19
, a system control unit (CNTU) consisting of the central processing unit (CPU) ;
20
, an operation panel (OP) ;
21
, a transceiver consisting of a speaker (SP) and a microphone (MIC) or the like. Vcc designates the power supply voltage. Moreover, the communication systems that can be used through the switching operation include the GSM system and DCS1800 system.
A radio signal processing circuit
18
is comprised of a modem processing unit, transmitting/receiving IF (intermediate frequency) unit and frequency converting unit (up-/down-converter) or the like and a radio signal (f
1
or f
2
) of any one of the GSM system of 0.9 GHz band or the DCS1800 system of 1.8 GHz band selected is generated and output at the transmitting time. These two kinds of radio transmitting signals f
1
, f
2
are input respectively to the first RF power module
15
and the second RF power module
16
.
The RF power module
15
is a power amplifier module corresponding to the GSM communication system and is comprised of an RF power MOS field effect transistor T
1
for final stage amplifier, matching circuits MC
1
and MC
2
consisting of passive elements, and an inductance element Lc
1
for DC choke of drain bias. In this case, the transistor T
1
is formed to provide an output, through the switching of a gate voltage to cutoff bias level and predetermined bias level, with the first bias control signal
22
output from the CPU of system control unit
19
interlocked with the GSM/DCS1800 selection switch of the mobile communication apparatus body.
In the same manner, the RF power module
16
is the power amplifier module corresponding to the DCS1800 communication system and is comprised of the RF power MOS field effect transistor T
2
for final stage amplifier, matching circuits MC
3
and MC
4
consisting of passive elements, and inductance element Lc
2
for DC choke of drain bias. In this case, the transistor T
2
is formed to provide an output, through the switching of gate voltage impressed to the transistor T
2
to the cutoff bias level and the predetermined bias level with the second bias control signal
23
output from the CPU of system control unit
19
interlocked with the GSM/DCS1800 selection switch of the mobile communication apparatus body.
The RF power modules
15
and
16
are respectively designed in optimum to set the matching with the matching circuits MC
1
to MC
4
so that the radio signals of the respective communication systems can be amplified effectively.
Thereby, the apparatus is operated as a hand-held telephone set of the GSM system, the bias control signal
22
of the RF power module
15
is set to the predetermined bias level and meanwhile the bias control signal
23
of the RF power module
16
is set to the cutoff bias level. Thereby, it is possible to selectively operate only the RF power module
15
to amplify the GSM radio signal f
1
(0.9 GHz band).
When the apparatus is operated as a hand-held telephone set of the DCS1800 system, the bias control signal
23
of the RF power module
16
is set to the predetermined bias level and meanwhile the bias control signal
22
of the RF power module
15
is set to the cutoff bias level, thereby only the RF power module
16
is selectively operated to amplify the DCS1800 radio signal f
2
(1.8 GHz band).
The structure explained above is selectively used depending on the setting of communication system by respectively providing the exclusive RF power modules within the apparatus for two communication systems. The RF power modules provided within the apparatus are designed in the optimum manner for respective communication system, assuring economical and effective operation.
Moreover, the radio frequency power amplifier module used in the hand-held telephone set is required to satisfy the specifications of the high frequency characteristic determined by each system such as the output power and is also required to satisfy further high efficiency and reduction in size.
Here, the technique to control the harmonics is well known as the technique to realize further high efficiency operation of the power amplifier for transmitter. For example, the Japanese Published Unexamined Patent Application No. SHO 60(1985)-109310 discloses the structure that one end part of the 1/4 wavelength transmission line is terminated at a higher frequency, while the other end thereof is connected to an amplifier element and a series resonant circuit to obtain the desired basic waveform signal output from the serial resonant circuit. With this structure, the connecting point of the output side of the amplifying element and 1/4 wavelength transmission line is terminated for the basic waveform and odd number order harmonics and thereby the ideal class F operation mode in which a current and a voltage at the output terminal of the amplifying element become zero can be obtained, and high efficiency can also be attained.
The high frequency power amplifier circuit of the related art forms a power amplifier circuit, as illustrated in FIG.
8
(
a
), by connecting the other end of the 1/4 wavelength transmission line
24
with one end thereof is terminated for high frequency signal to the output side of an amplifying element
25
and one end of a series resonance circuit
26
and the other end of the series resonance circuit
26
to an output terminal
27
. Here, when the amplifying element
25
operates upon input of a basic signal, the voltages are distributed on the 1/4 wavelength transmission line
23
. FIG.
8
(
b
) illustrates the condition of voltage distribution on the 1/4 wavelength transmission line
24
. This voltage distribution can be obtained for signal inputs of basic frequency signal and double-frequency signal. Sine one end II of the 1/4 wavelength transmission line
24
is perfectly terminated for high frequency signal, the voltages are applied to the connection part I to open for the basic frequency signal and to terminate for the double-frequency signal. Moreover, above voltage distribution is similar to the third h
Fujioka Toru
Kagaya Osamu
Katsueda Mineo
Matsunaga Yoshikuni
Morikawa Masatoshi
Hitachi , Ltd.
Mattingly Stanger & Malur, P.C.
Nguyen Patricia T.
Pascal Robert
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