Apparatus for optimizing the performance of a power amplifier

• US 5,880,635 A
• Filed: 04/16/1997
• Issued: 03/09/1999
• Est. Priority Date: 04/16/1997
• Status: Expired due to Term

• Current Assignee: Sony Corporation (Sony Group Corp.), Sony Electronics Inc. (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.), Sony Electronics Inc. (Sony Group Corp.)
• Inventors: Satoh, Naotaka
• Primary Examiner(s): MOTTOLA, STEVEN J
• Application Number:
  US08/839,882
• Time in Patent Office: 692 Days
• Field of Search: 330/129, 330/144, 330/145, 330/279, 330/284
• US Class Current: 330/144
• CPC Class Codes: H03F 1/56 Modifications of input or output impedances, not otherwise provided for
• CPC Class Codes: H03G 3/3042 in modulators, frequency-changers, transmitters or power amplifiers transmission power control in bidirectional transmission systems H04W52/04

Abstract

The performance of a power amplifier used in a signal transmitter, such as in a communication system (e.g., a personal communication system PCS), is optimized by coupling a controllable impedance to the output impedance of the power amplifier. The power output level of the amplifier, which is variable over a range from a minimum level to a maximum level and which is accompanied by a corresponding amplifier output impedance change, is detected, as is the operating power supplied to the amplifier. The controllable impedance that is coupled to the amplifier output is controlled as a function of the detected amplifier power output level and sensed operating power.

Claims

1. Apparatus for optimizing the performance of a power amplifier in a signal transmitter, comprising:

a power amplifier supplied with operating power for amplifying a signal to be transmitted, said power amplifier having a source impedance and an output impedance and exhibiting a power output level that is variable over a range from a minimum level to a maximum level, and wherein said output impedance changes as said power output level varies;

an adjustable matching circuit coupled to said output impedance of said power amplifier and exhibiting a controllable impedance which comprises controllable inductance means;

power detecting means coupled to an output of said power amplifier for detecting said power output level and for producing a power level indicating signal indicative of the detected power output level;

operating power sensing means for detecting the operating power supplied to said power amplifier and for producing an operating supply indicating signal indicative of the operating power supplied to said power amplifier; and

impedance control means coupled to said power detecting means and to said operating power sensing means for controlling said controllable impedance of said matching circuit as a function of said power level and operating supply indicating signals.

3. The apparatus of claim 1 wherein said operating power sensing means comprises current detector means for detecting operating current supplied to said power amplifier from a power supply source.

2. Apparatus for optimizing the performance of a power amplifier in a signal transmitter, comprising:

a power amplifier supplied with operating power for amplifying a signal to be transmitted, said power amplifier having a source impedance and an output impedance and exhibiting a power output level that is variable over a range from a minimum level to a maximum level, and wherein said output impedance changes as said power output level varies;

an adjustable matching circuit coupled to said output impedance of said power amplifier and exhibiting a controllable impedance, said matching circuit including a field effect transistor (FET) having an output impedance;

power detecting means coupled to an output of said power amplifier for detecting said power output level and for producing a power level indicating signal indicative of the detected power output level;

operating power sensing means for detecting the operating power supplied to said power amplifier and for producing an operating supply indicating signal indicative of the operating power supplied to said power amplifier; and

impedance control means coupled to said power detecting means and to said operating power sensing means for controlling said controllable impedance of said matching circuit as a function of said power level and operating supply indicating signals;

said impedance control means being operable to supply a control signal to said FET to adjust the output impedance thereof.

4. Apparatus for optimizing the performance of a power amplifier in a signal transmitter, comprising:

a power amplifier supplied with operating power for amplifying a signal to be transmitted, said power amplifier having a source impedance and an output impedance and exhibiting a power output level that is variable over a range from a minimum level to a maximum level, and wherein said output impedance changes as said power output level varies;

an adjustable matching circuit coupled to said output impedance of said power amplifier and exhibiting a controllable impedance;

power detecting means coupled to an output of said power amplifier for detecting said power output level and for producing a power level indicating signal indicative of the detected power output level;

operating power sensing means for detecting the operating power supplied to said power amplifier and for producing an operating supply indicating signal indicative of the operating power supplied to said power amplifier;

said operating power sensing means comprising voltage controlling means for supplying a controllable operating voltage to said power amplifier such that said operating voltage increases when said power output level increases and said operating voltage decreases when said power output level decreases, and said operating supply indicating signal is representative of the operating voltage supplied to said power amplifier; and

impedance control means coupled to said power detecting means and to said operating power sensing means for controlling said controllable impedance of said matching circuit as a function of said power level and operating supply indicating signals.

6. The apparatus of claim 4 wherein said power detecting means comprises a directional coupler having an input port coupled to said power amplifier output, a power output port for providing the amplified signal to be transmitted and an indicating signal port for providing said power level indicating signal as a function of the power amplifier output.

7. The apparatus of claim 4 wherein said impedance control means comprises a processor and a look-up table, said look-up table storing impedance control values associated with respective power level and operating supply indicating signals, and said processor uses the power level and operating supply indicating signals produced by said power detecting and operating power sensing means to produce an address for addressing said look-up table.

8. The apparatus of claim 4 wherein said matching circuit includes a voltage-controlled capacitance and said impedance control means is operable to supply a control voltage to said voltage-controlled capacitance as a function of said power level and operating supply indicating signals.

9. The apparatus of claim 8 wherein said voltage-controlled capacitance comprises a varicap diode.

5. Apparatus for optimizing the performance of a power amplifier in a signal transmitter, comprising:

a power amplifier supplied with operating power for amplifying a signal to be transmitted, said power amplifier having a source impedance and an output impedance and exhibiting a power output level that is variable over a range from a minimum level to a maximum level, and wherein said output impedance changes as said power output level varies;

an adjustable matching circuit coupled to said output impedance of said power amplifier and exhibiting a controllable impedance;

power detecting means coupled to an output of said power amplifier for detecting said sower output level and for producing a power level indicating signal indicative of the detected power output level, said power detecting means comprising capacitor means coupled to said power amplifier output for producing a voltage as a function of said power output level;

operating sower sensing means for detecting the operating power supplied to said power amplifier and for producing an operating supply indicating signal indicative of the operating sower supplied to said power amplifier; and

impedance control means coupled to said power detecting means and to said operating power sensing means for controlling said controllable impedance of said matching circuit as a function of said power level and operating supply indicating signals.