JPH06164281A - High frequency band and high output amplifier - Google Patents

Abstract

PURPOSE:To provide a high frequency band and high output amplifier applicable to a system requiring a small channel spacing in which a problem of inter-adjacent channel interference due to distortion exists, and of small size and light weight without generating the distortion, and capable of issuing high efficiency/low distortion output. CONSTITUTION:The control circuit 34 of the high frequency band high output amplifier performs positive feedback control of an input application voltage to the gate of a final stage amplifier element 11 via an input side voltage supply part 23 setting a signal in which an input offset voltage Vgs offset is added on an input detection signal envelope-detected at an adder 32 as the input application voltage. When input with large amplitude is inputted, it arrives as the input of the final stage amplifier element 11 via a DC amplifier 20 and the adder 32, and a voltage feedback circuit 19 is operated setting operating points as classes B, C, then, the making of high efficiency/low distortion can be attained. When input with middle or small amplitude is inputted, the input of the final stage amplifier element 11 becomes shallow since the output of an input side detecting part 13 is decreased, and the operating point is moved to class A, and wave distortion can be improved by performing amplification in a linear operating area.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency band high power amplifier, and more particularly to a final stage amplifier of the high frequency band high power amplifier in a communication terminal station.

[0002]

2. Description of the Related Art Conventionally, as an amplifier circuit configuration of this type, as shown in FIG. 3, class B and class C operation FET amplifiers (final stage amplifying element) having excellent efficiency as compared with class A operation amplifiers. ) 11, the voltage feedback circuit 19 that has been subjected to the saturating-line feedback is intended to achieve high efficiency and low distortion.

This high frequency band high power amplifier has an input connector 10a which receives a high frequency modulated input signal 10-1 as an input.
Depletion type field effect transistor (FE
T) An amplifier which is the final stage amplification element 11 provided at the final stage, and an initial stage amplification element 1 provided for exciting the high frequency modulation input signal 10-1 and outputting the amplified signal 12-1
2, an input side voltage supply unit 23 connected to the gate of the final stage amplification element 11 and supplying a gate voltage Vgs fix, a voltage feedback circuit 19 for giving negative feedback to the high frequency band high output signal 10-2, and amplified to a high output. High frequency band high output signal 10
It has an output connector 10b for sending -2.

The voltage feedback circuit 19 removes a distortion component distorted by an operation in a non-linear region such as class B or class C in order to maintain a highly efficient operation. This voltage feedback circuit 19 has an input side detector 13a and an amplified signal 12-
1 is provided with an input detector 13, an output detector 15a and an attenuator 15b, which output a detection signal 13-1 obtained by detecting the modulation wave component of the amplified signal 12-1 by performing the saturation detection and amplification. Detection signal 15- which is obtained by extracting the modulation component of the signal 11-2
1, an output detector 15 that outputs 1, and a difference detector 1 that detects a difference 16-1 between the detected signal 13-1 and the detected signal 15-1.
6. The difference amplification unit 17 that amplifies the difference 16-1 and outputs the amplified difference signal 17-1 and the supply unit 18 that supplies the amplified difference signal 17-1. As a result, the output voltage control of the final stage amplification element is performed based on the input signal having the distortion component, and as a result, the distortion component after amplification is reduced while maintaining the high effects of class B and class C. Even when the power consumption is reduced, when the feedback of the conventional saturated wave detection is performed, the output applied voltage of the final stage amplification element 11 follows the modulated wave saturated line as shown in FIG. The variable power consumption reduces the average power consumption, resulting in high efficiency.

Referring to FIG. 5, Vin in the case where the final stage amplifying element 11 of this high frequency band high power amplifier is operated in class B
The -Iout characteristic curve (Vgs-IDS characteristic curve) is shown. The final stage amplifier element 11 is a depletion type and operates in a depletion region in which Vgs is negative. In the case of class B operation shown as an example of how to apply a bias, a class B operating point (Vgs fix = pinch off voltage Vp
At the operating point), receiving the input voltage Vin as an input,
A half cycle of the input voltage Vin is energized and amplified. In the amplification element output voltage control based on such input / output signal saturation detection, the amplification element input applied voltage is fixed.
At the pinch-off point Vp, when the input voltage Vi is (a) large amplitude input, (b) medium amplitude input, (c) small amplitude input waveforms (a ′), (b ′), (c) ´) is obtained.

[0006]

By the way, the input voltage V
When in is a large-amplitude input, it operates in the region of the Vin-Iout characteristic curve line, which is effective for improving efficiency and reducing distortion. On the other hand, when the input voltage Vin has a small amplitude input, it operates in the non-linear region of the Vin-Iout characteristic curve line and a little distortion occurs, but in the input / output state where clipping does not occur, it has an effect on high efficiency and low distortion. There is no.

However, when the medium amplitude is input, V
Since the rise of Iout of the in-Iout characteristic curve enters the non-linear region, the output waveform is considerably distorted, so that the output waveform is extremely lowered due to the distortion.

[0008] Therefore, it is difficult to realize a system that requires small frequency spacing division that causes interference between adjacent channels due to distortion, that is, a system that requires small channel spacing.

Therefore, the technical problem of the present invention can be applied to a system requiring a small channel spacing in which interference between adjacent channels due to distortion is a problem, and there is no distortion and high efficiency and low distortion output can be obtained. To obtain a possible high-frequency band high-power amplifier.

[0010]

According to the present invention, a part of the input and a part of the output of a FET amplifier provided as the final stage of a high-power amplifier are respectively detected, and the output detection voltage is the input voltage. In a high-frequency band high-power amplifier configured to control the FET amplifier so as to match the detection voltage, the input detection signal is input to a DC amplifier, and a voltage obtained by adding the output voltage with an input offset voltage is applied to the FET amplifier. A high-frequency band high-power amplifier having a control circuit for controlling an input applied voltage can be obtained.

[0011]

[Operation] According to the amplitude of the input detection signal detected by the saturating line detection,
The bias point at the input of the FET amplifier is controlled. That is,
The operating region, which is the operating point of the input of the FET amplifier, appropriately shifts according to the amplitude of the input detection signal. When the input detection signal has a large amplitude, the predetermined operating point of the FET amplifier shifts to the class B operating region. Further, when the input detection signal has a medium amplitude or less, since there is waveform distortion, the predetermined operating point of the FET amplifier shifts to the class A operating region.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A high frequency band high power amplifier according to an embodiment of the present invention will be described with reference to the drawings.

Referring to FIG. 1, the high frequency band high power amplifier of this embodiment is different from the conventional example in that a control circuit 34 is provided. The control circuit 34 controls the final stage amplification element 11
A circuit for performing positive feedback control so as to shift the operating region, which is the operating point, to a predetermined region, an input-side voltage supply unit 23, a DC amplifier 30 for amplifying the input detection signal that has undergone the saturation detection.
Input offset voltage Vgs o to the amplified input detection signal
and an adder 32 that adds ffset.

The operation of the high frequency band high power amplifier of this embodiment will be described.

For a large amplitude input, the input side detector 13
The output voltage of a becomes large, and the DC amplifier 30 and the adder 3
2, via the input side voltage supply unit 23, the final stage amplification element 11
Input to the gate. The input applied voltage of the final stage amplification element 11 is a pinch-off voltage in the case of class B operation,
In the case of class C operation, it is deeply biased to the negative side. Here, the settings of class B and class C are made by changing the gain of the DC amplifier 30. The feedback operation of the satiation detection is applied to the input applied voltage of the final stage amplifier element 11, and B,
High efficiency and low distortion at high output due to class C can be achieved.

For a medium amplitude input, the output voltage of the input side detector 13a is smaller than that for a large amplitude input, and the voltage applied to the gate of the final stage amplification element 11 is
It is shallowly biased to the negative side and operates in class A. Therefore,
Since the operating point moves from the non-linear region to the linear region, and the medium-amplitude swing is performed in the linear operating region on the Vin-Iout characteristic, the waveform distortion is improved compared to the conventional class B and C fixed biases. To be done.

Further, for a small amplitude input, the voltage applied to the gate of the final stage amplification element 11 is close to 0V, which is a shallow operating point. Even if the output voltage of the DC amplifier 30 moves to 0V and becomes 0V, the input applied voltage is the input offset voltage Vgs off added to the adder 32.
Since it is not shallower than set, class A operation is guaranteed.

As described above, the high-frequency band high-power amplifier of this embodiment operates mainly for low distortion because the efficiency is small for small and medium amplitude inputs.

[0019]

As described above, the present invention is provided with the control circuit, and the FET is responsive to the input detection signal detected by the saturated line detection.
The type of the modulated high frequency signal input to the high frequency band high power amplifier, that is, PSK (phase shift) is controlled by dynamically controlling the input / output applied voltage of the final stage amplification element that appropriately shifts the operating region, which is the operating point of the amplifier. It can be applied to systems that require small channel spacing, which causes interference between adjacent channels due to side lobes of modulated waves due to distortion, regardless of the (modulation) method, without distortion, and has high efficiency and low distortion. It becomes possible to convert the output.

Further, according to the present invention, since the radiator for heat radiation can be made small, the communication terminal station can be made small and lightweight.

[Brief description of drawings]

FIG. 1 is a block diagram of a high frequency band high power amplifier according to an embodiment of the present invention.

FIG. 2 is a Vgs-IDS characteristic curve for explaining the shift of the operating point of the FET amplifier of FIG.

FIG. 3 is a block diagram of a conventional example of a high-frequency band high-power amplifier.

4A and 4B are waveforms of a modulated wave component, a modulated wave satiety line, and a high frequency band high output signal of FIG.

5 is a Vin-Iout (Vgs-IDS) characteristic curve for explaining the shift of the operating point of the FET amplifier of FIG.

[Explanation of symbols]

 10a Input plug 10b Output plug 11 Final stage amplification element 12 First stage amplification element 13 Input side detection unit 13-1 Detection signal 13a Input side detection unit 15 Output side detection unit 15-1 Detection signal 15a Output side detection unit 15b Attenuator 16 difference detector 16-1 difference 17-1 amplified difference signal 18 output side voltage supply section 19 voltage feedback circuit 23 input side voltage supply section 30 DC amplifier 32 adder 34 control circuit

Claims (1)

[Claims] 1. A FET amplifier provided as a final stage of a high-power amplifier, detects a part of an input and a part of an output of the FET amplifier, and the FET detection voltage is matched with the input detection voltage. In a high-frequency band high output amplifier configured to control the above, a control circuit for controlling the applied voltage at the input of the FET amplifier by inputting the input detection signal to a DC amplifier and adding the output voltage with an input offset voltage A high-frequency band high-power amplifier having.