JPH05152976A - High frequency power amplifier circuit - Google Patents

Abstract

(57) [Summary] [Objective] To increase the manufacturing yield of a high-frequency power amplifier circuit configured by using distributed constants such as strip lines, and to be able to cope with a wide range of changes in operating conditions such as bias. [Configuration] An impedance matching circuit of a high frequency power amplifier circuit is configured using distributed constants, and part of the impedance matching circuit is replaced with an electrically controllable variable impedance circuit. [Effect] Since the variations in the input / output impedance characteristics depending on the characteristics of the amplification element such as MOSFET and GaAsFET can be individually corrected by the electrical setting, the above object is achieved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a high frequency power amplifier circuit,
Further, the present invention relates to a technique effective when applied to a multi-stage high frequency power amplification module using an insulated gate FET (field effect transistor) as an amplification element, and uses radio waves in the ultra high frequency band such as UHF or SHF. The present invention relates to a technique effectively used for a mobile radio communication device.

[0002]

2. Description of the Related Art In a radio communication device that uses radio waves in the ultra-high frequency band such as UHF or SHF, in order to power-amplify a low-frequency modulated high-frequency signal and feed it to an antenna,
A high frequency power amplifier circuit modularized as a hybrid integrated circuit is often used. As shown in FIG. 5, this type of high frequency power amplifier circuit includes drive circuits 1 and 2 and a final stage circuit 3.
In the multi-stage configuration, the circuits 1, 2 and 3 in each stage are each configured by using an insulated gate FET such as MOSFET or GaAs FET. Each circuit 1, 2,
The input / output parts of 3 are impedance matching circuits 4 and 4, respectively.
The input / output impedance (50Ω) of a certain standard is provided by 5, 6, and 7. The impedance matching circuits 4 to 7 are configured by combining the distributed constants of the strip line 8 and the like with fixed capacitors C1 to C4 and a fixed resistor R1 (for example, Japanese Patent Laid-Open Nos. 62-53009 and 62-120130). Japanese Patent Laid-Open No. Sho 58-1
14513).

[0003]

However, the present inventors have clarified that the above-mentioned technique has the following problems. That is, in an impedance matching circuit using distributed constants such as strip lines, the circuit constants are fixed depending on the dimensions and the like, and it is very difficult to change them. On the other hand, MOSFET and GaAs FET
The characteristics such as the gate capacitance of the amplifying element such as the above often vary greatly at the manufacturing stage.

For this reason, the above-mentioned high-frequency power amplifier circuit generally has poor input / output impedance reproducibility, and if it is attempted to obtain a circuit that conforms to the standard accurately, there is a problem that the manufacturing yield is significantly reduced. It was Also, MO
Insulated gate type FET such as SFET and GaAs FET
, The gate capacitance related to its input impedance also changes depending on the bias voltage. Therefore, the operating range of the above-described high-frequency power amplifier circuit is narrowed down, and it may not be possible to control the output power by varying the bias voltage in a wide range.

It is a first object of the present invention to provide a technique for increasing the manufacturing yield of a high frequency power amplifier circuit configured by using distributed constants such as strip lines. A second object of the present invention is to provide a high degree of freedom in the input / output impedance characteristics of a high frequency power amplifier circuit configured by using distributed constants such as strip lines so that it is possible to cope with a wide range of changes in operating conditions such as bias. To provide the technology to do so. The above and other objects and features of the present invention will be apparent from the description of the present specification and the accompanying drawings.

[0006]

Among the inventions disclosed in the present application, a brief description will be given to the outline of typical ones.
It is as follows. That is, the impedance matching circuit of the high frequency power amplifier circuit is configured using distributed constants, and a part of the impedance matching circuit is replaced with an electrically controllable variable impedance circuit.

[0007]

According to the above-mentioned means, MOSFET and GaA
It becomes possible to individually correct the variations in the input / output impedance characteristics depending on the characteristics of the amplification element such as the sFET. As a result, the object of increasing the manufacturing yield of the high frequency power amplifier circuit configured by using distributed constants such as strip lines is achieved. Further, it is also possible to achieve the object of giving flexibility to the input / output impedance characteristic of the high-frequency power amplifier circuit so as to be able to deal with a wide range of changes in operating conditions such as bias.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding parts. FIG. 1 shows an embodiment of a high frequency power amplifier circuit according to the present invention. The high-frequency power amplifier circuit shown in the figure is modularized as a hybrid integrated circuit for use in a transmitter of a mobile radio communication device in the quasi-SHF band, where 1 is a preliminary drive circuit and 2 is a final stage drive circuit. 3 is a final stage circuit, 4 to 7 are impedance matching circuits using distributed constants such as the strip line 8, 9
Is a variable impedance circuit forming a part of the impedance matching circuit, IN is an input, and OUT is an output.

Each of the drive circuits 1 and 2 and the final stage circuit 3 is composed of an insulated gate FET such as MOSFET or GaAs FET. The impedance matching circuits 4 to 7 intervene in the input / output portions of the circuits 1, 2 and 3 at the respective stages so that the input / output impedances of the circuits are fixed to a certain standard (5
0Ω). Here, in the impedance matching circuit 4 of the input section, a part of the circuit constant is replaced with the variable impedance circuit 9 by the variable capacitance diode D1. That is, the input impedance matching circuit 4 is configured by the fixed constants such as the strip line 8, the fixed capacitors C1 to C6, the fixed resistor R1 and the like and the variable constant by the variable capacitance diode D1.

The capacitance of the variable capacitance diode D1 forming the variable impedance circuit 9 changes according to the voltage applied in the opposite direction. The voltage for setting the capacitance of the variable capacitance diode D1 is divided by the resistors R2 and R3,
Also, it is supplied from the outside through an AC blocking circuit (decoupling) by the resistor R4 and the capacitor C6. Reference numeral 10 is an input terminal for the voltage Vc for setting the capacitance. FIG. 2 shows a layout configuration example of the impedance matching circuit 4, in which the strip line 8 is fixedly formed by a conductor pattern on an insulating substrate. Chip-shaped fixed capacitors are also attached to the capacitors C1 to C3, C5 and C6.

On the other hand, of the resistors R1 to R4, the resistors R2 and R3 which divide the voltage applied to the variable capacitance diode D1 are given arbitrary resistance values by laser trimming or the like. 11 and 12 are resistors R respectively
2 shows trimming marks of R3. As described above, a part of the input impedance matching circuit 4 configured by using the distributed constant of the strip line 8 is replaced with the variable impedance circuit 9 including the variable capacitance diode D1.

In the high frequency power amplifier circuit described above, the MOS
The variations in the input impedance characteristics depending on the individual characteristics of the amplifying elements such as FET and GaAsFET can be individually corrected by trimming the resistors R2 and R3 that divide the voltage applied to the diode D1. This trimming correction can be performed after the formation of the strip line 8 and the attachment of the amplification element are completed. As a result, the manufacturing yield of the high frequency power amplifier circuit configured by using the distributed constants of the strip line 8 and the like can be increased.

Here, in addition to the above-mentioned configuration, if the control voltage of the variable impedance circuit 9 is configured to be linked to the bias voltage of the amplification element, the bias voltage is changed for the output control of the high frequency power amplification circuit. However, it is also possible to automatically correct the input / output impedance change of the amplification element due to the change of the bias voltage so as to obtain the specified impedance characteristic in a wide output range. Further, as shown in FIG. 3, the variable impedance circuit 9 described above may be provided on the input side of the impedance matching circuit 4.

Further, as shown in FIG. 4, the control voltage of the variable impedance circuit 9 may be given from the operating power supply voltage Vdd of the high frequency power amplifier circuit. In the embodiment shown in the figure, a constant voltage circuit 13 using a Zener diode Dz is provided, and the constant voltage output of this constant voltage circuit 13 is applied to the variable capacitance diode D1 via the voltage dividing circuit of the resistors R2 and R3. It is like this. The impedance matching circuit 5, which is interposed between the stages and the output section,
6, 7 can also be configured similarly to the above case.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say. For example, the control voltage of the variable impedance circuit 9 may be variably set using a semi-fixed resistor such as a small potentiometer. In the above description, the invention made by the present inventor was mainly applied to the high frequency power amplification module forming the transmitter of the mobile radio communication device which is the background field of application, but the invention is not limited thereto. Instead, it can be applied to a high-frequency power amplifier circuit for wired communication using a transmission line such as a coaxial cable.

[0016]

The outline of the typical inventions among the inventions disclosed in the present application will be briefly described as follows. That is, it is possible to obtain the effect that the manufacturing yield of the high-frequency power amplifier circuit configured by using distributed constants such as strip lines can be increased.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of a high frequency power amplifier circuit according to the present invention.

FIG. 2 is a diagram showing a layout state of an impedance matching circuit used in the circuit of the present invention.

FIG. 3 is a diagram showing a second embodiment of a high frequency power amplifier circuit according to the present invention.

FIG. 4 is a diagram showing a third embodiment of the high frequency power amplifier circuit according to the present invention.

FIG. 5 is a diagram showing a configuration example of a conventional high frequency power amplifier circuit.

[Explanation of symbols]

 1 Preliminary drive circuit 2 Final stage drive circuit 3 Final stage circuit 4 to 7 Impedance matching circuit 8 Stripline 9 Variable impedance circuit D1 Variable capacitance diode R2, R3 Trimming resistor IN input OUT output

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Nagai 111 No. Nishiyokote-cho, Takasaki-shi, Gunma Hitachi Ltd. Takasaki Plant

Claims (7)

[Claims] 1. A high-frequency power amplifier characterized in that the impedance matching circuit of the high-frequency power amplifier circuit is constructed using distributed constants, and part of the impedance matching circuit is replaced with an electrically controllable variable impedance circuit. Amplifier circuit. 2. The high frequency power amplifier circuit according to claim 1, wherein a part of the impedance matching circuit is replaced with a variable capacitance diode whose capacitance value is set by a voltage applied via a resistance element. .. 3. The high frequency power amplifier circuit according to claim 1, wherein the amplifier element is an insulated gate field effect transistor. 4. The high frequency power amplifier circuit according to claim 1, wherein the control voltage of the variable impedance circuit is interlocked with the bias voltage of the amplifier element. 5. The high frequency power amplifier circuit according to claim 1, wherein the control voltage of the variable impedance circuit is applied from a power supply voltage through a constant voltage circuit and a resistance voltage dividing circuit. 6. The high frequency power amplifier circuit according to claim 1, wherein a control voltage is applied to the variable impedance circuit via a resistor whose resistance value is set by trimming. 7. The high frequency power amplifier circuit according to claim 1, wherein the high frequency power amplifier circuit constitutes a transmitter of a mobile radio communication device that uses radio waves in a frequency band of UHF or higher. Power amplifier circuit.