JP2001244753A - High-frequency power amplifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-frequency power amplifier, that can more simply correct nonlinear distortions caused by an amplified signal which results from nonlinearity in an input output characteristic of the power amplifier. SOLUTION: A mixer of the power amplifier compensates the linearity by controlling a level of an oscillated signal for up-conversion, in response to the level of input IF signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in the linearity of a power amplification response of a high-frequency power amplifier.

[0002]

2. Description of the Related Art As a method of improving the linearity of a power amplification response of a high-frequency power amplifier using a conventional technique, a method using a feedforward (FF) amplifier, a method using a negative feedback amplifier, and the like are known.

[0003]

The above-mentioned method using an FF amplifier, a method using a negative feedback amplifier, and the like have disadvantages in that the circuit configuration for realizing those methods is complicated, the number of components is large, and the cost is high. is there.

[0004]

According to the present invention, the characteristics of the mixer in the conversion section are utilized to control the level of the oscillation signal for performing up-conversion in the mixer in accordance with the level of the input IF signal. It compensates for linearity.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG.
This will be described below. IF input to IF signal input terminal 1
The signal passes through the directional coupler 2 and is up-converted by the mixer 3 according to the LO signal, and the band-pass filter (BP)
F) An RF signal is obtained by band limitation at 4. That R
The F signal is input to the power amplifier 8 to become an RF signal of a predetermined power, and output from the RF signal output terminal 9. Here, at the time of high power output operation, distortion generated in the power amplifier 8 becomes large and cannot be ignored. Therefore, in order to cancel the distortion, the level of the IF signal input to the IF signal input terminal 1 is detected via the directional coupler 2, and the control circuit 7 controls the pin attenuator 6 in accordance with the detected level. Control. By controlling the pin attenuator 6 as described above, the level of the LO signal that is the oscillation signal of the LO signal oscillator 7 is changed. Then, the LO signal whose level has been changed in this way can distort the RF signal output from the mixer 3 in a phase opposite to that of the above-described distortion in the power amplifier 8, thereby obtaining a pre-distortion effect. Thus, the linearity compensation of the power amplifier can be realized.

[0006]

As described above, according to the present invention, for example, in a TV broadcaster, characteristics such as a differential gain characteristic and an amount of lower band wave reproduction are improved. In addition, when a plurality of waves are simultaneously amplified, intermodulation distortion can be improved, so that a simple and inexpensive power amplifier can be obtained. Further, by improving the linearity, the operation level of the power amplifier increases, and higher efficiency can be achieved as compared with an amplifier without compensation.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the overall configuration of the present invention.

[Explanation of symbols]

1: IF signal input terminal, 2: directional coupler, 3: mixer, 4: bandpass filter (BPF), 5: LO signal oscillator, 6: pin attenuator, 7: control circuit, 8: high frequency power amplifier, 9 : RF signal output terminal.

Continued on the front page F-term (reference) 5J090 AA01 AA41 CA21 CA36 CA92 FA20 GN03 GN07 KA00 KA23 KA32 KA44 KA68 MA14 MA20 SA08 TA01 5J091 AA01 AA41 CA21 CA36 CA92 FA20 KA00 KA23 KA32 KA44 KA68 CA14 MA20 A20 CA01 KA00 KA23 KA32 KA44 KA68 MA14 MA20 SA08 TA01 VL08 VL10

Claims (1)

[Claims] A high-frequency power amplifier for up-converting an input signal into a high-frequency signal and then amplifying the power,
A high-frequency power amplifier that controls a level of a transmission signal input to a mixer for the up-conversion according to a level of the input signal.