JP2806129B2 - Transmission power control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave communication device, and more particularly to a transmission power control device for controlling transmission power.

[0002]

2. Description of the Related Art A conventional transmission power control apparatus has a variable attenuator 1 for varying the level of a modulated signal to be transmitted by a control signal as shown in FIG. A frequency converter 2 for frequency conversion;
A variable gain amplifier 3 for amplifying the output of the frequency converter 2, a detector 4 for detecting the output level of the variable gain amplifier 3, and a comparator for comparing the output of the detector 4 with a reference voltage 5 and an AG for outputting an AGC voltage for controlling the gain of the variable gain amplifier 3 so that the output of the detector 4 becomes equal to a reference voltage by the output of the comparator 5.
A C control circuit 6, a reference voltage generator 7 for generating a reference voltage for the comparator 5 according to an external control signal, and similarly control the attenuation of the variable attenuator 1 according to an external control signal. It has a variable attenuator control circuit 9.

[0003] This conventional transmission power control device is used for a transmission section of a radio communication station facing the same. The external control signal is control information sent from the opposite station to control the transmission output of the own station according to the reception level at the opposite station. For example, when the reception level at the receiving station is lower than a predetermined level, the output of the reference voltage generator 7 is changed by an external control signal, and the AGC control circuit 6 controls the variable gain amplifier 3 so that the gain of the variable gain amplifier 3 increases. The amplifier 3 is controlled. At this time, an increase in the power consumption of the transmitter due to an increase in the gain and an increase in the output of the amplifier in a case where output distortion such as pre-distortion is compensated.
In order to prevent the secondary distortion from increasing, the attenuation of the variable attenuator 1 is reduced by the variable attenuator control circuit 9 so that the variable gain amplifier 3
Is made to be constant.

[0004]

In this conventional transmission power control apparatus, the control of the attenuation of the variable attenuator 1 and the control of the gain of the variable gain amplifier 3 are performed by independent control circuits 9 and 6, respectively. It is necessary to control two points by an external control signal. For this reason, it is necessary to adjust the control circuits so that the operation timings of the respective control circuits 9 and 6 match, or to provide a separate circuit for adjusting the timing, which complicates the operation or complicates the structure. There was a point. SUMMARY OF THE INVENTION An object of the present invention is to provide a transmission power control device that controls a variable attenuator and a variable gain amplifier only by controlling one point by an external control signal, thereby preventing a complicated operation and a complicated structure. .

[0005]

SUMMARY OF THE INVENTION The present invention relates to a configuration for controlling the amount of attenuation of a variable attenuator and the gain of a variable gain amplifier in accordance with an external control signal, for controlling the output of the variable gain amplifier to a reference output. AG output from the AGC control circuit
There is a variable attenuator control circuit that receives the AGC voltage and controls the variable attenuator so that the C voltage becomes a constant value.
Further, the variable attenuator control circuit has a hysteresis characteristic in controlling the attenuation of the variable attenuator with respect to the AGC voltage change.

[0006]

The variable attenuator control circuit controls the variable gain amplifier so that the output voltage of the AGC control circuit for controlling the variable gain amplifier becomes constant while controlling the output level of the variable gain amplifier by an external control signal. To make the gain of the variable gain amplifier constant.

[0007]

Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of one embodiment of the present invention. The modulated wave output from the modulator is controlled in attenuation by a variable attenuator 1, is further converted into a radio frequency by a frequency converter 2, and the gain is controlled by a variable gain amplifier 3 to be output at a predetermined level. The output level is controlled to be constant by controlling the variable gain amplifier 3 by the AGC control circuit 6. That is, this control is performed by the detector 4
The AGC control circuit 6 compares the detected voltage output from the variable gain amplifier 3 with the reference voltage generated by the reference voltage generator 7 so that the output of the detector 4 becomes equal to the reference voltage. Is variable. The transmission power control changes the output level by varying the output voltage of the reference voltage generator 7 according to an external control signal. The variable attenuator 1 is controlled by a variable attenuator control circuit 8 to control the amount of attenuation.
Is controlled based on the output of.

FIG. 3 is a diagram showing the relationship between the gain of the variable gain amplifier 3 and the AGC voltage of the output of the AGC control circuit 6 and the amount of attenuation of the variable attenuator 1. Referring to FIG. The operation of the control circuit 8 will be described. The reference voltage generator 7 outputs the reference voltage V _REF1 or V _{REF2 according} to the external control signal. Here, it is assumed that V _REF1 is a voltage for increasing the output level of the variable gain amplifier 3 and V _REF2 is a voltage for _decreasing the output level, and binary transmission power control is performed.

When V _REF2 changes to V _REF1 , the output level becomes high, so that the gain of the variable gain amplifier 3 becomes G in FIG.
_STD changes to _GH . At this time, the attenuation of the variable attenuator 1 is reduced by the amount of gain increase (ATT OFF). As a result, the input level of the variable gain amplifier 3 rises, and the gain again becomes G _H → G _STD . Since the variable attenuator control circuit 8 has a hysteresis as shown in FIG. 3, G _H
→ Even if G _STD , the attenuation of the variable attenuator 1 does not change.

Further, when V _REF1 changes to V _REF2 , the output level decreases, and the gain of the variable gain amplifier 3 changes to G _STD → _GL in FIG. At this time, the attenuation of the variable attenuator 1 is increased by the amount of the decrease in the gain (ATT ON). As a result, the input level of the variable gain amplifier 3 decreases, so that the gain becomes G _L → G _STD . Since the variable attenuator control circuit 8 has hysteresis as described above, G _L → G
Even if it becomes _STD , the attenuation of the variable attenuator 1 does not change.

[0011]

As described above, according to the present invention, the variable attenuator control circuit controls the amount of attenuation of the variable attenuator based on the AGC voltage output from the AGC control circuit, whereby the input level of the variable gain amplifier is controlled. To control AGC
Since the variable attenuator is controlled so that the voltage is constant, only the reference voltage generator needs to be controlled by an external control signal. In addition, since the control of the variable attenuator is not performed independently, the control timing No adjustment is required, operation is simplified,
This has the effect of preventing the structure from becoming complicated.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of a transmission power control device of the present invention.

FIG. 2 is a block diagram of a conventional transmission power control device.

FIG. 3 is a characteristic diagram showing a relationship between a gain of a variable gain amplifier, an AGC voltage, and a variable attenuator control circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Variable attenuator 2 Frequency converter 3 Variable gain amplifier 4 Detector 5 Comparator 6 AGC control circuit 7 Reference voltage generator 8 Variable attenuator control circuit

Claims (2)

(57) [Claims] 1. A variable attenuator for varying an input modulation signal level by a control signal, a frequency converter for converting the output of the variable attenuator into a radio frequency, and amplifying the output of the frequency converter. A variable gain amplifier for
A detector for detecting said variable gain amplifier output level, external
To generate different reference voltages according to the control signal
Controlling a reference voltage generator, a comparator for comparing the reference voltage and the detector output, the gain of the variable gain amplifier so that by the comparator output is equal to the detector output to the reference voltage To output AGC voltage for
C control circuit, and detects the AGC voltage,
A transmission power control device comprising: a variable attenuator control circuit that controls the variable attenuator so that a pressure becomes a constant value. Wherein said variable attenuator control circuit, the AGC
2. The transmission power control device according to claim 1 , wherein the variable power attenuator for the voltage change has a hysteresis characteristic.