US 5,589,796 AGranted

Method and apparatus for increasing amplifier efficiency

AssigneeMotorola, Inc.

InventorsWilliam P. Alberth, Jr., John J. Janssen, Armin Klomsdorf

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Abstract

A transmitter (107) includes amplifying circuitry (203) and control circuitry (215, 217, 219) for biasing the amplifying circuitry (203) so that it operates closer to saturation with increased efficiency. The gate voltage signal (213), which provides a gate bias, is coupled to the amplifying circuitry (203) and is dynamically varied by the processor circuitry (219) in response to the value of the amplifier control voltage (211) coupled to the amplifying circuitry (203). The amplifier control voltage (211), which has a value for maintaining the output power of the amplifying circuitry (203) at a constant, is produced by the integrating circuitry (217) in response to a comparison of the detected power output signal (216) produced by the detecting circuitry (215) and the power output control signal (218) produced by the processor circuitry (219). Efficiency is realized by dynamically varying the gate voltage signal (213) to its largest magnitude so that the amplifying circuitry (203) may operate as close to saturation as possible while still maintaining a constant output power.

Claims13

Dependent claims

Control circuitry for controlling amplifying circuitry, the amplifying circuitry for amplifying an input signal into an amplified output signal, the amplifying circuitry coupled to a power source and having a first, a second, and a third input, an output, a saturation point, an amplification magnitude responsive to an amplifier control signal, and a gate bias responsive to a gate voltage signal, the input signal coupled to a first input of the amplifying circuitry, the amplifier control signal coupled to a second input of the amplifying circuitry, the gate voltage signal coupled to a third input of the amplifying circuitry, the amplified output signal having an output power level and coupled to an output of the amplifying circuitry, the control circuitry comprising:

detecting circuitry for detecting the output power level of the amplified output signal, said detecting circuitry coupled to the output of the amplifying circuitry;
integrating circuitry, responsive to said detecting circuitry, for generating the amplifier control signal for setting the amplification magnitude of the amplifying circuitry so that the output power level of the amplified output signal remains at a constant level, said integrating circuitry coupled to an output of said detecting circuitry and coupled to the second input of the amplifying circuitry;
and
processor circuitry for dynamically varying the gate voltage signal to its largest operative magnitude causing the amplifying circuitry to function at or near the saturation point for increased efficiency, said processor circuitry coupled to said integrating circuitry, the third input of the amplifying circuitry, and to the power source.

1 more element

Control circuitry for controlling a multi-stage amplifier, the multi-stage amplifier comprised of a power amplifier driver and a power amplifier for amplifying an input signal into an amplified output signal, the power amplifier driver having a first and a second input, an output, and an amplification magnitude responsive to an amplifier control signal, the power amplifier coupled to a power source and having a first input coupled to the output of the power amplifier driver, a second input, an output, a saturation point, and a gate bias responsive to a gate voltage signal, the input signal coupled to the first input of the power amplifier driver, the amplifier control signal coupled to the second input of the power amplifier driver, the gate voltage signal coupled to the second input of the power amplifier, the amplified output signal having an output power level and coupled to the output of the power amplifier, the control circuitry comprising:

a directional coupler for electromagnetically coupling the amplified output signal from the output of the power amplifier without excessive loss;
a detector, responsive to the directional coupler, for generating a detected power output signal indicative of the output power level of the amplified output signal;
a microprocessor for generating a power output control signal comprised of a predetermined value dictating the output power level of the amplified output signal;
an integrator, coupled between the detector and an output of the microprocessor, for comparing the detected power output signal to the power output control signal;
a buffer, responsive to the integrator, for increasing or decreasing a magnitude of the amplifier control signal for setting the amplification magnitude of the power amplifier driver so that the output power level of the amplified output signal remains at a constant level;
and
an operational amplifier configuration, responsive to a voltage generated for dictating an increase or a decrease in the gate voltage signal via a comparison of the amplifier control signal and the power source to determine if the multi-stage amplifier is in saturation, for generating a negative magnitude of the gate voltage signal to operate the power amplifier at or near the saturation point for increased efficiency.

4 more elements

A method of controlling amplifying circuitry, the amplifying circuitry coupled to a power source and having a first, a second, and a third input, an output, a saturation point, a gate bias responsive to a gate voltage signal, and amplifying an input signal responsive to an amplifier control signal into an amplified output signal, the input signal coupled to the first input of the amplifying circuitry, the amplifier control signal coupled to the second input of the amplifying circuitry, the gate voltage signal coupled to the third input of the amplifying circuitry, the amplified output signal coupled to the output of the amplifying circuitry, the method of controlling the amplifying circuitry comprising the steps of:

(a) detecting a power level of the amplified output signal and generating a detected output power level signal;
(b) integrating the detected output power level signal and a power level control signal into the amplifier control signal;
(c) generating the amplifier control signal so that the amplified output signal remains constant;
and
(d) dynamically varying the gate voltage signal to a most negative operative magnitude such that the amplifying circuitry functions at or near the saturation point for increased efficiency.

2 more elements

Dependencies are inferred from the claim text.