JPH03183203A - Transmission power control circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical field to which the invention pertains) The present invention relates to a transmission power control circuit for keeping the transmission power of a transmitter constant regardless of changes in temperature and frequency.

(Prior Art and Its Disadvantages) An automatic power control circuit (APC circuit) is known as a conventional method of controlling transmission power. An example of the circuit configuration is shown in FIG. In FIG. 1, 1 is a variable gain amplifier, 2
is the final stage power amplifier, 3 is a directional coupler, 4 is a detector, and 5 is a DC amplifier with a voltage comparison function that outputs an output that changes according to the human power only when the human power is higher than the set voltage. . In this circuit, when the transmission output increases and the detection output obtained by detecting a part of the transmission output extracted from the directional coupler 3 by the detector 4 exceeds the set voltage, the output power of the DC amplifier 5 increases. The output of the power amplifier 2 is kept constant by lowering the gain of the variable gain amplifier 1. Such a conventional circuit has the drawback that the characteristics of the directional coupler 3 and the wave detector 4 change due to changes in ambient temperature and changes in the transmission frequency, resulting in changes in the transmission output.

In other words, the characteristics of the directional coupler 3 and the detector 4 generally change depending on frequency and temperature, so in conventional circuits, they cannot be used in transmitters that are switched over a wide frequency range or transmitters that are used in a wide ambient temperature range. However, in order to keep the transmission output constant, there were problems such as the addition of a complicated compensation circuit and the need for delicate adjustments.

(Object of the Invention) An object of the present invention is to provide a transmission power control circuit free from these drawbacks by adding a simple characteristic compensation circuit.

(Structure and operation of the invention) The transmission power control circuit of the present invention is a transmission power amplifier circuit that amplifies a transmission input signal by a variable gain amplifier and a power amplifier and sends it out as a transmission output. a first non-volatile memory in which a control voltage value for compensating for the transmission power amplifier circuit is written in advance; a second non-volatile memory in which a control voltage value for compensating for frequency-dependent gain changes of the transmission power amplifier circuit is written in advance; an adder that reads and adds corresponding control voltage values from the first and second nonvolatile memories based on the ambient temperature detection output and transmission frequency data; and a D/A converter that converts the output of the adder into an analog voltage. , and is configured such that the output of the D/A converter is applied to the variable gain amplifier to control the gain so that the transmission output is substantially constant regardless of changes in temperature and frequency. That is.

The present invention will be explained in detail below with reference to the drawings.

FIGS. 2 and 3 are circuit block diagrams of a first embodiment and a second embodiment of the present invention.

In FIG. 2, numerals 6 and 7 are variable gain amplifiers and power amplifiers, which are the same as in the conventional configuration shown in FIG. 9 is a temperature sensor, and 10 is a nonvolatile memory (memory A, for example, ROM) in which a control voltage value for the variable gain amplifier 6 necessary for compensating the gain characteristics of the amplifier with respect to temperature is written. II is a similar memory (memory B) in which similar control voltage values regarding frequency are written, 12 is an adder (ADD), 13
is a D/A converter.

In the circuit shown in FIG. 2, a control voltage value corresponding to the ambient temperature detected by the temperature sensor 9 is read from the memory 10, and a control voltage value corresponding to the input transmission frequency data is read from the memory 11. , the outputs of both are added by an adder 12.

The voltage obtained by converting the addition output into an analog signal by the D/A converter 13 becomes a gain control voltage that compensates for gain fluctuations due to both temperature and frequency. By applying this gain control voltage to the variable gain amplifier 6, the transmission output becomes constant regardless of changes in temperature or frequency. Memory 10 and 1
The data to be written in advance in No. 1 is created by measuring the gain characteristics of the amplifier with respect to temperature and frequency so that the transmission output remains constant regardless of changes in temperature and frequency.

FIG. 3 shows a second embodiment of the present invention, in which readout control and addition of the memories 10 and 11 in FIG. 2 are performed by a computer (
This is done by the CPU. In this example, the creation and writing of data to be written into memory is also executed by the CPU program.

The dotted line in Figure 3 indicates the transmitter, 14°15,
17.19.20.21 are the same as 6.7.9, 10°11, and 13 in Fig. 2, which are a variable gain amplifier, a power amplifier, a temperature sensor, memory A, memory B, and a D/A converter. 18
is the CPU. 22 is a power meter, and 23 is an A/D converter, which are external circuits used when writing to the memory.

In normal transmission operation, the compensation control voltage value (direction) corresponding to the temperature is read out from the memory 19 by the CPU 18, and the compensation control voltage value corresponding to the frequency is read out from the memory 20 by the CPU 18.
8, added by CPU1B, and D/A
It is converted into an analog signal by the converter 21 and becomes a gain control voltage for the variable gain amplifier 14.

Data is written to the memories 19 and 20 by using a power meter 22 and an A/D converter 23 in an external circuit, and a gain control voltage value when the transmission power is set to a predetermined value is written into the memory.

By performing this at necessary temperature and frequency intervals, a table to be stored in memory is created. It is relatively easy to make the CPU 18 execute such a program.

In the second embodiment shown in FIG. 3, if the CPU is used to control other circuits of the transmitter, it is not possible to use the CPU for this transmission power control. Needless to say.

(Effect of the invention) The advantages of implementing the invention are as follows.

It is possible to configure a power amplifier circuit with flat temperature characteristics and transmission frequency characteristics, and there is no need for complicated compensation circuits or delicate adjustments, which has great effects on device manufacturing. Furthermore, directional couplers and detectors with good frequency characteristics and temperature characteristics are generally expensive, and the economical effect of not using them is also large.

Furthermore, since the main part is a digital circuit, there is little change over time, which is a great practical advantage.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a conventional transmission power control circuit.
FIG. 2 is a circuit block diagram showing a first embodiment according to the invention, and FIG. 3 is a circuit block diagram showing a second embodiment according to the invention. 1.6.14...Variable gain amplifier, 2,7.15...
・Power amplifier, 3... Directional coupler, 4... Detector, 5... DC amplifier, 9, 17... Temperature sensor, 1
0. II. 19, 20...Memory, I2...Adder, 13.2
1...D/A converter, 18...CPtJ, 22...
- Power meter, 23...A/D converter. Figure 2 Figure 2

Claims (1)

[Claims] In a transmission power amplifier circuit that amplifies a transmission input signal using a variable gain amplifier and a power amplifier and sends it out as a transmission output, a control voltage value for compensating for gain changes due to temperature of the transmission power amplifier circuit is set in advance. A first non-volatile memory in which data is written, a second non-volatile memory in which a control voltage value for compensating for frequency-dependent gain changes of the transmission power amplifier circuit is written in advance, and the An adder that reads and adds corresponding control voltage values from first and second nonvolatile memories, and a D/A converter that converts the output of the adder into an analog voltage, the D/A converter 1. A transmission power control circuit, characterized in that the transmission power control circuit is configured such that the output of the variable gain amplifier is applied to the variable gain amplifier to control the gain so that the transmission output remains approximately constant regardless of changes in temperature and frequency.