JPH05267941A - High efficiency type high frequency power amplifier - Google Patents

Abstract

PURPOSE:To provide the high frequency amplifier which can execute amplification with high accuracy even if a signal whose envelope is varied quickly is inputted, and has high efficiency as a whole. CONSTITUTION:The amplifier is provided with an envelope signal generating circuit 106 for generating an envelope of an input signal, and a detecting circuit 103 for detecting an output signal, and also, controls roughly a power supply voltage by a first variable power source circuit in which an output voltage is varied in accordance with an output of the envelope signal generating circuit 106, and also, controls minutely the power supply voltage by a second variable power source circuit 109 for controlling power source supply to a power source terminal 105 of a power amplifier 102 by an output of a comparing circuit 107 to which an output of a first variable power source circuit 108 is supplied, and which compares an output signal of the detecting circuit 104 and an output signal of the envelope signal generating circuit 106.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-efficiency type high frequency power amplifier used in a transmitting section of a wireless communication device.

[0002]

2. Description of the Related Art It is known that the power consumption of a wireless communication device depends on the power efficiency of a high frequency power amplifier arranged in a transmission section, and various methods have been proposed in order to improve the power efficiency. However, as wireless communication devices have been made smaller and lighter in recent years, it has been required to improve the power efficiency of the high frequency power amplifier due to the limitation of the capacity of the battery used as a power source.

As a method for improving the power efficiency of such a power amplifier, for example, one using the circuit of FIG. 2 can be considered. In FIG. 2, 201 is an input terminal, 202 is a power amplifier that amplifies a signal from the input terminal, 203 is an output terminal, 204 is a detection circuit that detects an output signal, and 205 is a power amplifier power supply that supplies power to the power amplifier. Supply terminal,
Reference numeral 206 denotes an envelope signal generation circuit that detects the envelope of the input signal and generates an envelope signal, and 207 denotes the detection circuit 204.
Is a variable power supply circuit for changing the power supply voltage by the signal from the comparison circuit 207, and 209 is a power supply input terminal for supplying power.

The operation will be described with reference to FIG. When a signal such as the input signal A is input to the input terminal 201,
The input signal A is saturated and amplified as shown by B by the power amplifier 202 set to the saturation amplification operation state. On the other hand, by comparing the signals of the envelope signal generation circuit 206 that generates the envelope signal component of the input signal A and the detection circuit 204 that detects the envelope signal component of the output signal D, the comparison circuit 207 causes both envelopes A control signal indicating the signal difference is output. By inputting the control signal to the variable power supply circuit 208, the power supply voltage C changes in proportion to the envelope signal component. By varying the voltage applied to the power supply terminal 205 of the power amplifier, the lost envelope component is reproduced and the output signal D is output to the output terminal 203. In this way, the power amplifier is operated for saturation amplification to improve power efficiency,
The envelope component (AM component) lost by the operation can be reproduced by changing the power supply voltage to be supplied.

An example of such a variable power supply circuit is Japanese Patent Laid-Open No. 62-
As shown in FIG. 6 of No. 274906, a circuit configuration in which a transistor acts as a variable resistor whose resistance value changes according to a control input (hereinafter referred to as a dropper type power supply circuit), or FIG. As shown in FIG. 8, a circuit configuration (hereinafter referred to as a switching type power supply circuit) in which the switching frequency is changed according to the control input and the oscillation output thereof is rectified by a rectifying circuit is considered.

[0006]

However, in the conventional variable power supply circuit of the power amplifier, when the switching power supply circuit is used, the power efficiency is good, but the envelope speed changes because the switching speed is limited. As shown in 4, the high-speed response becomes difficult and should be the envelope of Vb, but V
It becomes the envelope curve of a and the error becomes large. On the other hand, when the dropper type power supply circuit is used as the variable power supply circuit, the change in the envelope is followed, but there is a problem that the power efficiency is low.

[0007]

In view of the above problems, the present invention has a power amplifier having a signal input terminal, a signal output terminal and a power supply terminal, and an envelope for generating an envelope of an input signal of the power amplifier. A signal generation circuit, a detection circuit that detects the output signal of the power amplifier, a first variable power supply circuit whose output voltage changes according to the output of the envelope signal generation circuit, an output signal of the detection circuit, and the envelope. A comparison circuit for comparing the envelope signal from the signal generation circuit, is connected between the output terminal of the first variable power supply circuit and the power supply terminal of the power amplifier, and the output voltage changes according to the output of the comparison circuit. And a second variable power supply circuit configured as described above.

[0008]

According to the present invention, the variable power supply circuit of the power amplifier is divided into the first variable power supply circuit and the second variable power supply circuit, the voltage is roughly changed by the first variable power supply circuit, and then the output is further The second variable power supply circuit finely changes the power supply voltage of the power amplifier.

[0009]

FIG. 1 is a block diagram showing an embodiment of the present invention. In FIG. 1, 101 is an input terminal, 102 is a power amplifier that amplifies a signal from the input terminal, 103 is an output terminal, 104 is a detection circuit that detects an output signal, and 105 is a power amplifier power supply that supplies power to the power amplifier. Supply terminal,
Reference numeral 106 denotes an envelope signal generation circuit that detects the envelope of the input signal and generates an envelope signal, and 107 denotes the detection circuit 104.
A comparison circuit that compares the output of the envelope signal generation circuit 106 with the output of the envelope signal generation circuit 106; a first variable power supply circuit 108 that is a switching power supply circuit that changes the power supply voltage according to the output from the envelope signal generation circuit 106; Comparison circuit 10
The second variable power supply circuit 110 is a dropper type power supply circuit that changes the power supply voltage supplied to the power amplifier 102 according to the output from 7, and 110 is a power supply input terminal.

Next, the operation will be described with reference to FIG.
The envelope signal generation circuit 106 generates an envelope signal component from the input signal input from the input terminal 101. The envelope signal is directly input to the first variable power supply circuit 108. First
The variable power supply circuit 108 is a switching power supply circuit in which the envelope signal is supplied to the control input as shown in FIG.
The power supply voltage of the power amplifier 102 is changed like V1 in FIG. 5 in proportion to the envelope signal. Envelope signal generation circuit 106
The envelope signal of is further compared with the signal from the detection circuit 104 that detects the envelope of the output signal by the comparison circuit 107. The comparison circuit 107 outputs an error signal between the two signals. The second variable power supply circuit 109 is configured as shown in FIG. 7, and changes the power supply voltage of the power amplifier 102 at high speed as V2 in FIG. 5 according to the error signal. That is, the second variable power supply circuit 109 operates so as to compensate the envelope error generated by the first variable power supply circuit 108 indicated by the shaded portion in FIG.

Thus, the envelope component which is saturated and amplified by the operation and lost can be reproduced by changing the power supply voltage to be supplied, and as a whole, highly efficient and high-speed operation is possible. In addition, the envelope signal generation circuit 106
Instead of detecting the input signal and generating an envelope signal,
A circuit for generating an envelope signal based on data for modulating an input signal as shown by a broken line (for example, I and Q data when the input signal is obtained by quadrature modulating a baseband signal). But needless to say.

[0012]

According to the present invention, the power supply to the power amplifier is changed by the highly efficient first variable power supply circuit according to the envelope signal, and the output of the first variable power supply circuit has a high response characteristic. Since it was made to change further by the second variable power supply circuit of
A high-efficiency high-frequency linear power amplifier can be constructed as a whole.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram showing a conventional example.

FIG. 3 is a diagram showing a state of a signal during operation.

FIG. 4 is a diagram showing a state of an envelope.

FIG. 5 is a diagram showing a state of a power supply voltage of a power amplifier.

FIG. 6 is a diagram showing an example of a first variable power supply circuit.

FIG. 7 is a diagram showing an example of a second variable power supply circuit.

[Explanation of symbols]

 101 signal input terminal 102 power amplifier 103 signal output terminal 104 detection circuit 105 power amplifier power supply terminal 106 envelope signal generation circuit 107 comparison circuit 108 first variable power supply circuit 109 second variable power supply circuit 110 power supply input terminal 201 signal input terminal 202 power amplifier 203 signal output terminal 204 detection circuit 205 power amplifier power supply terminal 206 envelope signal generation circuit 207 comparison circuit 208 variable power supply circuit 209 power input terminal

Claims (4)

[Claims] 1. A power amplifier having a signal input terminal, a signal output terminal and a power supply terminal, an envelope signal generating circuit for generating an envelope of an input signal of the power amplifier, and an output signal of the power amplifier. A comparison circuit that compares the output signal of the detection circuit and the envelope signal from the envelope signal generation circuit, the first variable power supply circuit whose output voltage changes according to the output of the envelope signal generation circuit, A second variable power supply circuit connected between an output end of the first variable power supply circuit and a power supply terminal of the power amplifier and having an output voltage changed by an output of the comparison circuit. A high-efficiency high-frequency power amplifier featuring. 2. The first variable power supply circuit is a switching type high efficiency power supply circuit, and the second variable power supply circuit is a dropper type power supply circuit.
The high-efficiency type high frequency power amplifier described. 3. The high efficiency high frequency power amplifier according to claim 1, wherein the envelope signal generation circuit detects an envelope based on an input signal of the power amplifier and generates an envelope signal. 4. The high efficiency type high frequency power amplifier according to claim 1, wherein the envelope signal generating circuit generates an envelope signal based on digital data for modulation.