JPH06268458A - High output power amplifier - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to realize a high output power amplifier that suppresses oscillation, which is a problem in achieving high output in a high frequency high output power amplifier, and performs stable operation. [Structure] A high-frequency, high-output power amplifier that performs stable operation, and a power distribution circuit (3) for distributing an input signal input from an input line, and for amplifying the output of the power distributor. At least two amplification elements (4) connected in parallel with each other, and a power combining circuit (5) for combining the outputs of the respective amplification elements connected in parallel, and the power distribution circuit and the power combining circuit. Is formed of a coupled line type directional coupler (FIG. 2 (a)), and an oscillation prevention circuit (7, 8) is provided in at least one of the input / output terminals of the power amplifier.
Was set up. According to the present invention, there is an effect that oscillation of the high output power amplifier is prevented and stable operation is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high output power amplifier for communication, and more particularly to a high output power amplifier for operating a plurality of amplifiers in parallel in a high frequency band.

[0002]

2. Description of the Related Art Conventionally, a unit amplifier having an oscillation prevention circuit shown in FIG.
The high output power amplifier shown in FIG. 6 has been manufactured by combining and distributing power by a power distribution combiner such as (a) a branch type hybrid circuit and FIG. 4 (b) a Wilkinson type hybrid circuit.

In the unit amplifier of FIG. 5, the high frequency signal input to the high frequency input terminal 10 is input to the input side matching circuit 1.
1. The semiconductor device 13 is reached via the bias circuit 17 with the input side oscillation prevention circuit. Here, the high frequency signal is amplified and passes through the output side oscillation prevention circuit-equipped bias circuit 14 and the output side matching circuit 15 and reaches the high frequency output terminal 16.

In the high output power amplifier of FIG. 6, the high frequency signal input to the high frequency input terminal 20 is divided into four by the input side power combining / distributing circuit 21, is input to the unit amplifier 23, is amplified, and then is output side power combining. The distribution circuit 24 combines the four signals and outputs them to the high frequency output terminal 25.

[0005]

The power divider / combiner such as the branch type hybrid circuit and the Wilkinson type hybrid circuit used in the above-mentioned amplifier has sufficient isolation between the connected unit amplifiers at frequencies other than the used frequency. I can't get it. Therefore, even if each unit amplifier is stable, when it is operated in parallel, out-of-band oscillation occurs due to the sneak from one unit amplifier to the other unit amplifier due to variations in unit amplifier characteristics.

Therefore, an object of the present invention is to realize a high output power amplifier which suppresses oscillation which is a problem in achieving high output in a high frequency high output power amplifier and which operates stably.

[0007]

In order to achieve the above object, in a high output power amplifier of the present invention, a power distribution circuit for distributing an input signal input from an input line and an output of the power distributor are provided. At least two amplification elements connected in parallel for amplification, and a power combining circuit for combining the outputs of the respective amplification elements connected in parallel are provided, and the power distribution circuit and the power combining circuit are coupled to each other. A directional coupler is used, and an oscillation prevention circuit is provided on at least one of the input and output terminals of the power amplifier.

[0008]

The operation of the input / output power combining / distributing circuit is shown in FIGS.
By using the coupled line type directional coupler type shown in (3), it becomes possible to increase the isolation between the unit amplifiers operated in parallel at the out-of-band frequency. This utilizes the characteristic that the degree of coupling between two lines used in a coupled line type directional coupler decreases at an out-of-band frequency.

[0009]

EXAMPLES Examples of the present invention will be described in detail below. FIG. 1 is a high-power high-frequency amplifier using the present invention, and FIGS. 2A and 2B are external views of a quarter-wavelength 3 dB directional coupler which is an example of a circuit for performing power combination. The figure is shown. An equivalent circuit diagram is shown in (c).

In FIG. 1, the high frequency signal input from the high frequency input terminal 1 first enters the first input side coupled line type directional coupler 3 through the input side oscillation prevention circuit 7, and the power is split into two. Each divided power is further divided into two by the second input side coupled line type directional coupler and a total of 4
Distribution becomes unit amplifiers 4 (a) (b) (c)
It enters (d) and is amplified. The amplified signal enters the output side coupled line type directional coupler 5 to combine 4 signals into 2 signals, further combine the signals and reach the high frequency output terminal 6 via the output side oscillation prevention circuit 8.

When a 1/4 wavelength 3 dB directional coupler is used in the input / output power distribution / combining circuit, the coupling degree of each line used in the 1/4 wavelength 3 dB directional coupler is very high at the out-of-band frequency. It becomes smaller and each line becomes independent. Therefore, the high-frequency input terminal is connected to the input side of the unit amplifier 4 (a), and 5 is connected to the input side of the unit amplifier 4 (b).
0Ω termination resistor 2 (e) is connected, unit amplifier 4 (c)
A 50Ω termination resistor 2 (f) is connected to the input side of the unit amplifier 4
A 50Ω terminating resistor 2 (g) is connected to the input side of (d). Similarly, the output side of the unit amplifier 4 (a) is connected to the output side of the 50Ω terminating resistor 2 (h).
A 50Ω terminating resistor 2 (j) is connected to the output side of (b) and a 50Ω terminating resistor 2 is connected to the output side of the unit amplifier 4 (c).
In (i), the high-frequency output terminal 6 is connected to the output side of the unit amplifier 4 (d). That is, except for the input end of the unit amplifier 4 (a) and the output end of 4 (d), the 50Ω terminating resistor 2 is connected to all, and before the power distribution circuit on the input side,
And, by only providing one oscillation prevention circuit 7 or 8 after the power combiner circuit on the output side, a stabilizing load resistance is attached to the input and output of all the unit amplifiers, and the operation of the entire high output power amplifier is stabilized. Is.

The circuits shown in FIGS. 3A, 3B and 3C are
(A) is a circuit in which a high-pass filter is inserted in series in a signal line, and a low-pass filter in which a resistor is connected in series is connected in parallel to the signal line. ) Is a circuit in which a wideband isolator having a characteristic of absorbing reflected power from a direct current to an amplification frequency band is inserted in a signal line, and (c) is a capacitance C.
And an inductance L are connected in parallel to form a parallel resonant circuit, and a resistor connected in series to the circuit is inserted in parallel to the signal line.

[0013]

According to the present invention, a stable operation can be obtained by preventing an unstable phenomenon such as abnormal oscillation due to a reduction in isolation between unit amplifiers outside the amplification frequency band which occurs when a high output power amplifier is operated. To be

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a high output power amplifier using the present invention.

FIG. 2 is a diagram of a 3 dB directional coupler used in the present invention. (A) Planar circuit type 1/4 wavelength 3 dB directional coupler. (B) Coaxial line type ¼ wavelength 3 dB directional coupler. (C) An equivalent circuit diagram of a 1/4 wavelength 3 dB directional coupler.

FIG. 3 is a diagram for explaining an example of the present invention.

FIG. 4 is an equivalent circuit diagram of a power combiner / divider circuit that has been conventionally used. (A) An equivalent circuit diagram of a branch line type hybrid power combining and distributing circuit. (B) Wilkinson type hybrid power combining and distributing circuit equivalent circuit diagram.

FIG. 5 is an equivalent circuit diagram of a unit amplifier.

FIG. 6 is an overall configuration diagram of a conventional high output power amplifier.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... High frequency input terminal, 2 ... 50 Ω terminating resistor, 3 ... Input side coupling line type directional coupler, 4 ... Unit amplifier, 5 ... Output side coupling line type directional coupler, 6 ... High frequency output terminal, 7 ... Input Side oscillation prevention circuit, 8 ... Output side oscillation prevention circuit, 10 ... High frequency input terminal, 11 ... Input side matching circuit, 12 ... Bias circuit with input side oscillation prevention circuit, 13 ... Semiconductor device,
14 ... Bias circuit with output side oscillation prevention circuit, 15 ... Output side matching circuit, 16 ... High frequency output terminal, 17 ... Input side bias terminal, 18 ... Output side bias terminal, 20 ... High frequency input terminal, 21 ... Input side power combining Distribution circuit, 22 ... 50
Ω terminating resistor, 23 ... Unit amplifier, 24 ... Output side power distribution circuit, 25 ... High frequency output terminal.

Front page continuation (72) Inventor Haruhiko Funaki 216 Totsuka-cho, Totsuka-ku, Yokohama, Kanagawa Prefecture Space Technology Promotion Division, Hitachi, Ltd. (72) Inventor Akihiko Kobayashi 2-12-5 Iwamoto-cho, Chiyoda-ku, Tokyo (72) Inventor Teruki Okamoto 2-12-5 Iwamotocho, Chiyoda-ku, Tokyo Inside Space Communications Research Institute Co., Ltd.

Claims (5)

[Claims] 1. A high-frequency, high-output power amplifier that performs stable operation, comprising: a power distribution circuit for distributing an input signal input from an input line; and an amplifier for amplifying an output of the power distributor. At least two amplifier elements connected in parallel and a power combiner circuit for combining the outputs of the amplifier elements connected in parallel are provided, and the power distribution circuit and the power combiner circuit are coupled together. And a high-output power amplifier, characterized in that an oscillation prevention circuit is provided on at least one of the input and output terminals of the power amplifier. 2. The oscillation prevention circuit, when connected to the input terminal of the power amplifier, is connected to a high-pass filter connected to a signal line to which an input signal is input and an output terminal of the high-pass filter. And a resistor connected to the low-pass filter and the other to the ground, and the output end of the high-pass filter is arranged to be connected to the coupled line type directional coupler. A high output power amplifier according to claim 1 characterized. 3. The oscillation prevention circuit, when connected to the output terminal of the power amplifier, has a low-pass filter having one end connected to the output terminal, and one grounded and the other end of the low-pass filter. The high output power amplifier according to claim 1, wherein the high output power amplifier comprises a resistor connected to the low pass filter and a high pass filter connected to the other end of the low pass filter. 4. The oscillation prevention circuit comprises a parallel resonance circuit composed of a capacitance C and an inductance L resonating at an amplification frequency, and a resistor connected in series to the parallel resonance circuit. The high output power amplifier according to claim 1, wherein the input / output terminal of the power amplifier and the ground are connected in parallel. 5. The high output power amplifier according to claim 1, wherein the oscillation prevention circuit is a wide band isolator exhibiting a characteristic of absorbing reflected power from DC to an amplification frequency band.