Power saving device for radio communication terminal

Details Power saving device for radio communication terminal Power saving device for radio communication terminal

1998-12-16

2002-05-28

Maung, Nay (Department: 2681)

Telecommunications

Transmitter and receiver at same station

Radiotelephone equipment detail

C455S572000, C455S127500, C455S343200

Reexamination Certificate

active

06397090

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to radio communication terminals, and in particular, to a power saving device for reducing current consumption during a telephone conversation.
2. Description of the Related Art
In a CDMA (Code Division Multiple Access) or PCS (Personal Communication System) terminal, an RF (Radio Frequency) power amplifier is so designed as to have a maximum output power of +28dBm in order to satisfy the IS-98 standard and the J-STD-008 standard. In addition, a transmitter of the CDMA or PCS terminal includes an automatic gain control (AGC) amplifier for controlling the power level according to the strength of a received signal or a power control command transmitted from a base station. Accordingly, the terminal should increase the transmission power in an area where a signal transmitted from the base station has a low signal strength and decrease the transmission power in an area where the signal transmitted from the base station has a high signal strength.
In the meantime, the CDMA or PCS terminal, employing QPSK (Quadrature Phase Shift Keying) modulation, requires a linear amplifier. Therefore, the AGC amplifier adopts an A-class or AB-class bias. In such a case, however, the terminal consumes a constant current regardless of the transmission power.
FIG. 1
illustrates a conventional two-stage power amplifier. As illustrated, a driver amplifier
101
primarily amplifies an input RF signal RF
I
, and a final amplifier
103
secondarily amplifies the amplified RF signal output from the driver amplifier
101
. The driver amplifier
101
and the final amplifier
103
are both provided with a fixed level control signal (or a fixed gain control signal) to control the power level. Therefore, the amplifiers
101
and
103
consume a constant idle current regardless of the strength of the signal. This results in an increase in the current consumption.
To solve this problem, there is proposed a method of providing a variable voltage to the power amplifier to control a linear region of the power amplifier, thereby reducing the current consumption.
FIG. 2
illustrates an improved two-stage power amplifier. In the drawing, a variable voltage is provided to the driver amplifier
101
and the final amplifier
103
. When the transmission power is low, the variable voltage is lowered to reduce the idle current to the minimum value. In this way, it is possible to reduce the current consumption to some extent. However, each of the elements constituting the power amplifier have a different linear region. When some of the elements have a narrow linear region, it is difficult to obtain the desirable power saving effect. Furthermore, no matter how little the idle current flow may be reduced to, each stage of the power amplifier consumes the constant current. Thus, there is a limitation in the ability to reduce the current consumption. That is, even when the transmission power is low enough such that it is not necessary to drive the final amplifier, the idle current continues to flow into the final amplifier, wasting the current.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a power saving device for reducing current consumption by changing the number of power amplifying stages in a radio communication terminal.
To achieve the above object, there is provided a power saving device for a radio communication terminal including a first amplifier for high power and a second amplifier for low power including a signal path selector for switching an input signal to an input node of the first or second amplifier in response to a switching control signal. An output path selector selects one of the output signals from the first and second amplifiers in response to the switching control signal. An RSSI detector detects the signal strength of a signal received from a base station. A controller analyzes the detected signal strength, and generates a switching control signal of a first state, when the signal strength is low, to enable the signal path selector to switch the input signal to the first amplifier and enable the output path selector to select the output signal of the first amplifier. The controller also generates a switching control signal of a second state, when the signal strength is high, to enable the signal path selector to switch the input signal to the second amplifier and enable the output path selector to select the output signal of the second amplifier. A power supply blocks a first supply voltage to the first amplifier in response to the switching control signal of the second state, and blocks a second supply voltage to the second amplifier in response to the switching control signal of the first state.


REFERENCES:
patent: 3962553 (1976-06-01), Linder et al.
patent: 4323881 (1982-04-01), Mori
patent: 4449248 (1984-05-01), Leslie et al.
patent: 4804954 (1989-02-01), Macnak et al.
patent: 4964121 (1990-10-01), Moore
patent: 5054052 (1991-10-01), Nonami
patent: 5056109 (1991-10-01), Gilhousen et al.
patent: 5144296 (1992-09-01), DeLuca et al.
patent: 5179724 (1993-01-01), Lindoff
patent: 5203020 (1993-04-01), Sato et al.
patent: 5230096 (1993-07-01), Davies et al.
patent: 5241542 (1993-08-01), Natarajan et al.
patent: 5280650 (1994-01-01), Sobti
patent: 5287544 (1994-02-01), Menich et al.
patent: 5301225 (1994-04-01), Suzuki et al.
patent: 5369768 (1994-11-01), Takano
patent: 5381133 (1995-01-01), Erhart et al.
patent: 5384564 (1995-01-01), Wycoff et al.
patent: 5390357 (1995-02-01), Nobusawa et al.
patent: 5392287 (1995-02-01), Tiedemann, Jr. et al.
patent: 5428638 (1995-06-01), Cioffi et al.
patent: 5459457 (1995-10-01), Sharpe
patent: 5475374 (1995-12-01), Moore
patent: 5493282 (1996-02-01), Petreye et al.
patent: 5509015 (1996-04-01), Tiedemann, Jr. et al.
patent: 5513386 (1996-04-01), Ogino et al.
patent: 5565853 (1996-10-01), Jun-Young
patent: 5566081 (1996-10-01), Yoshizawa
patent: 5570369 (1996-10-01), Jokinen
patent: 5606728 (1997-02-01), Keba et al.
patent: 5638540 (1997-06-01), Aldous
patent: 5649315 (1997-07-01), Eaton
patent: 5666355 (1997-09-01), Huah et al.
patent: 5710981 (1998-01-01), Kim et al.
patent: 5734686 (1998-03-01), Kuramatsu
patent: 5740517 (1998-04-01), Aoshima
patent: 5740524 (1998-04-01), Pace et al.
patent: 5742636 (1998-04-01), Fukushi
patent: 5758269 (1998-05-01), Wu
patent: 5774813 (1998-06-01), Jokinen
patent: 5797090 (1998-08-01), Nakamura
patent: 5799256 (1998-08-01), Pombo et al.
patent: 5831479 (1998-11-01), Leffel et al.
patent: 5862460 (1999-01-01), Rich
patent: 5956638 (1999-09-01), Chang et al.
patent: 5999829 (1999-12-01), Chun et al.
patent: 6101373 (2000-08-01), Samuels

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