JPH02172309A - Power amplifier - Google Patents

Abstract

PURPOSE:To decrease the gain deviation of a power amplifier circuit in a minute frequency step and to attain stable power control by providing a gain variable means able to be controlled by a digital signal and a conversion table controlling the variable means. CONSTITUTION:An input signal 4 passes though a pin attenuator(PIN ATT) 1 and is inputted to a digital ATT 6. The digital ATT 6 is controlled by a ROM 7 and the attenuation of the digital ATT 6 is varied for each minute frequency step so as to make the gain deviation of a power amplifier circuit 2 depending on the frequency. On the other hand, the ROM 7 stores the attenuation in response to the frequency step and outputs the attenuation in response to the signal of frequency information 8 to the digital ATT 6. Then a power detection circuit 3 detects power, converts the output power into a DC voltage to control the PIN ATT 1 thereby controlling the power inputted to the digital ATT 6. Thus, the high frequency power outputted from the power amplifier circuit 2 is more stably controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a power amplifying device that requires broadband performance, and particularly to power control of a device used at the final stage of a transmitter.

[Conventional technology]

Conventionally, there has been a power amplification system of this type as shown in FIG. In the figure, 1 is a bin attenuator (hereinafter referred to as PI
N.A. TT), 2 is a power amplifier circuit, and 3 is a power detection circuit. (Automa
tic Level Control) loop. Further, 4 is an input signal, and 5 is an output signal.

Next, the operation will be explained. Input signal 4 is PIN A
After passing through the TTI, the power is amplified in the power amplifier circuit 2, and the power of the power amplified high frequency signal is detected in the power detection circuit 3, and then converted into a DC voltage. With this DC voltage, PIN ATTl operates to increase the amount of attenuation when the output power is large, and to decrease the amount of attenuation when the output power is small. In this way, the power of the output signal 5 output from the power amplifier circuit 2 is controlled to be constant.

[Problem to be solved by the invention]

Conventional power amplifiers are configured as described above, so when wideband power amplification is performed, the frequency characteristics of the gain of the power amplifier circuit vary widely, and as a result, the loop gain of the ALC loop is not constant, resulting in power control There were drawbacks such as increased variations in power after the process and increased variations in loop stabilization time.

This invention was made in order to solve the problems of the conventional ones as described above, and provides a power amplifier that can more stably control the power after power control and can reduce the variation in ALC loop stabilization time. The purpose is to obtain equipment.

[Means to solve the problem]

The power amplifier according to the present invention is provided with gain variable means such as digital ATT or digital DC amplifier at required locations in the ALC loop, and this gain variable means is controlled by a conversion table such as ROM. .

[Effect]

In this invention, the gain variable means and the conversion table are provided in the ALC loop, and the gain variable means is controlled by the conversion table that stores gain data for each fine frequency step. It is possible to correct variations in gain due to frequency, and to reduce gain deviation of the power amplifier circuit.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure shows a power amplifier device according to an embodiment of the present invention, and in the figure, 6 is a digital ATT.

7 is a ROM, and 8 is frequency information. Other components are the same as in FIG.

Next, the operation will be explained. Input signal 4 is PIN A
After passing through the TTI, it is input to the digital ATT6. This digital ATT6 is controlled by a ROM7, and the digital ATT6 varies the amount of attenuation for each fine frequency step in order to keep the gain deviation of the power amplifier circuit 2 constant depending on the frequency. On the other hand, ROM7 stores the attenuation amount corresponding to each frequency step,
The amount of attenuation according to the signal of frequency information 8 is digitally ATT
Output to 6. In this way, digital ATT 6ROM?
By using the power amplifier circuit 2, an amplifier circuit with small gain deviation can be configured with fine frequency steps.

Then, the power detection circuit 3 converts the output power into a DC voltage by detecting the power, controls the PIN ATTI by this DC voltage, and connects the digital AT
Controls the power input to T6.

In this way, the high frequency power output from the power amplifier circuit 2 can be controlled more stably.

In the above embodiment, a digital ATT 6 is provided between the PIN ATTI and the power amplifier circuit 2, but as shown in FIG. The ATT6 may be provided, and the same effects as in the above embodiment can be obtained.

Moreover, as shown in FIG. 3, the power detection circuit 3 and the PIN
A digital DC amplifier 9 may be provided between the ATTI and the output signal power by amplifying the detected voltage of the power detection circuit with the digital DC amplifier, and the same effect as in the above embodiment can be achieved. play.

〔Effect of the invention〕

As described above, according to the power amplifier according to the present invention,
Since a gain variable means that can be controlled by a digital signal and a conversion table for controlling it are provided, the gain deviation of the power amplifier circuit can be reduced with fine frequency steps, and more stable power control can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a power amplifying device according to an embodiment of the present invention, FIG. 2 is a diagram showing a second embodiment of the present invention in which a digital ATT is provided in the front stage of a power detection circuit, and FIG. FIG. 4 is a block diagram showing a conventional power amplification system. In the figure, 1 is the PIN ATT, 2 is the power amplifier circuit, 3 is the power detection circuit, 6.9 is the digital ATT, digital DC amplifier (gain variable means), 7 is the ROM (conversion table), and 20 is the ALC loop (automatic). level control loop).

Claims (1)

[Claims] (1) In a power amplifier device that requires broadband performance, an attenuator that attenuates the input signal, a power amplifier circuit that amplifies the output of this attenuator, and a power amplifier that detects the power of the output signal output from this power amplifier circuit to the outside and an automatic level control loop consisting of a power detection circuit that outputs a control signal to an attenuator; a variable gain means that is inserted at a required point in the automatic level control loop and amplifies or attenuates the signal at the inserted point according to a digital control signal; A power amplification device comprising: a conversion table for converting external frequency information into a gain control signal for the gain variable means.