Amplifiers – Combined with automatic amplifier disabling switch means
Reexamination Certificate
1999-10-18
2001-07-24
Pascal, Robert (Department: 2817)
Amplifiers
Combined with automatic amplifier disabling switch means
C330S133000, C330S297000
Reexamination Certificate
active
06265935
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a radio transmission amplifier unit for use, for instance, in a mobile communication system that requires substantial control of the transmitting power from each mobile station.
PRIOR ART
For example, in a CDMA-based mobile communication system the base station sends a transmitting power control signal to respective mobile stations to control their transmitting powers so as to make the receiving levels of transmitting waves from any mobile stations substantially constant regardless of the distances between the mobile stations and the base station, thereby reducing interference that is attributable to the difference in receiving level among channels assigned with different spreading codes.
In
FIG. 1A
there is depicted a conventional radio transmission amplifier unit that forms part of a radio transmitter of a mobile station. The radio transmission amplifier unit has a variable gain-controlled amplifier (GCA)
11
, a pre-amplifier
12
and a main amplifier
13
. An input signal from an input terminal
10
is amplified by GCA
11
, then its output is amplified by the pre-amplifier
12
, and the amplified output is further amplified by the main amplifier
13
having a gain larger than that of the pre-amplifier
12
, thereafter being provided to an output terminal
14
. Though different according to its kind, the mobile station performs transmission, for example, with a maximum rated transmitting power of 0.3 W, normally, tens of milliwatts or so, for instance. Upon each reception of a transmitting-power-increase control signal from the base station, the mobile station controls GCA
11
to increase the transmitting power by a predetermined gain (dB), whereas, upon each reception of a transmitting-power-decrease control signal, it controls GCA
11
to decrease the transmitting power by a predetermined gain (dB).
FIG. 1B
shows, by way of example, an increase in the transmitting power controlling degree and variations in the operation efficiency of such a radio transmission amplifier unit by repeated reception of the transmitting-power-increase control signal. The conventional radio transmission amplifier unit is so designed as to provide maximum efficiency when the transmitting power is at the maximum as shown in FIG.
1
B. Consequently, when the transmitting power is low, the operation efficiency considerably decreases, resulting in a waste of power. This is particularly detrimental to a mobile station that uses a battery as the power supply as in the case of a portable telephone.
An object of the present invention is to provide a radio transmission amplifier unit which retains high efficiency even during its operation with a transmitting power smaller than the rating.
DISCLOSURE OF THE INVENTION
According to a first aspect of the present invention, a radio transmission amplifier unit, which amplifies a signal fed to an input terminal and provides it to an output terminal, is constructed to comprise:
a plurality of amplifiers provided between said input terminal and said output terminal and each having a power-supply terminal;
power supply means for supplying power to said plurality of amplifiers;
power-supply switching means for selectively connecting said power supply means to the power-supply terminals of said plurality of amplifiers to supply thereto power;
route switching means for switching the cascade connection of said plurality of amplifiers to connect the output of a selected one of said amplifiers to said output terminal; and
control signal generating means for generating switch control signals which specify the states of connection by said power-supply switching means and said route switching means in accordance with a transmitting power controlling degree corresponding to the transmitting power level and for applying said switch control signals to said power-supply switching means and said route switching means, respectively.
The radio transmission amplifier unit according to said first aspect of the invention may also be constructed so that first and second bias voltages are selectively supplied by a bias select switching means from said power supply means to the input sides of said plurality of amplifiers.
According to a second aspect of the present invention, a radio transmission amplifier unit, which amplifies a signal fed to an input terminal and provides it to an output terminal, is constructed to comprise:
a plurality of amplifiers connected in cascade between said input terminal and said output terminal, each amplifier having a power supply terminal;
power supply means for outputting at least first and second bias voltages;
bias select switching means for selectively applying either one of said first and second bias voltages to the input sides of said plurality of amplifiers to thereby selectively set their operating points; and
control signal generating means for generating a bias control signal which controls the selection of said bias select switching means in correspondence to the transmitting power level.
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Hagiwara Seiji
Kaneda Ryuusuke
Takami Tadao
Choe Henry
Connolly Bove Lodge & Hutz
NTT Mobile Communications Network Inc.
Pascal Robert
LandOfFree
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