JPH01138805A - Transmission power controller - Google Patents

Abstract

PURPOSE:To attain power control immune to a temperature change by obtaining a reference signal from an input signal of an amplifier, comparing the amplified signal with the reference signal before detection so as to control the gain of the amplifier from the result thereby eliminating the need for a diode. CONSTITUTION:A high frequency signal from an input terminal (a) is amplified by a power amplifier 1, led to an output terminal (b) and part of it is given to a differential amplifier 3 via a capacitor 2. Moreover, the input high frequency signal is given to a phase adjusting device 4 and its output signal and the signal via the capacitor 2 are adjusted by a phase comparator 5 so as not to cause a phase difference. The adjusted high frequency signal is attenuated by the attenuation rate corresponding to a level control signal sent from a base station at a variable attenuator 6 and the result is inputted to the amplifier 3. The amplifier 3 compares both the input signals and the output signal controls the gain of the amplifier 1 via a rectifier 8 so that both are zero. Thus, prescribed transmission power is easily and accurately obtained. Since no diode is employed, it is not required to care about temperature change.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a transmission power sub-device for use in mobile radio equipment such as in-vehicle and portable radio telephones.

2. Description of the Related Art In general, the distance from a base station to a vehicle-mounted radio telephone, a portable radio telephone, etc. varies greatly, so it is necessary to automatically control transmission power accordingly to prevent interference.

For this reason, in this type of mobile radio system, a base station has traditionally sent out a level system signal to each mobile radio device, indicating how much transmission power should be used for that mobile radio device. Based on the level side leg signal, each radio telephone automatically adjusts its transmission power to correspond to the level side leg signal.

FIG. 3 is a schematic diagram of a conventional transmission power control device that enables such control.

In Fig. 5, a is an input terminal into which a high-frequency signal for transmission is input, and the high-frequency signal for transmission inputted here is outputted via a gain-invertible amplifier 102, etc. It is led to a terminal and applied to an isolator, etc. A part of the output of the amplifier 102 is transferred to the capacitor 10
3, detected by diode 104, and resistor 1o5. After being smoothed by a capacitor 106, it is applied to one input terminal of a comparator circuit 107. The other input terminal of the comparison circuit 107 is applied to the side overturn signal input terminal C.

It is configured so that a signal for level control that has been D/A converted by a D/A conversion circuit 108 is input, and the level of the signal detected by a diode 104 and smoothed by a resistor 105° capacitor 106 is the above-mentioned level. If the level of the side-turning signal is different from that of the side-turning signal, the above-mentioned comparison circuit 1
The output of the power amplifier 107 drives the overturning circuit 109 to change the gain of the power amplifier 101.

The detected and smoothed signal is turned to the side so that it becomes the same level as the level control signal.

Therefore, even with the conventional transmission power adjustment device configured in this manner, the transmission power can be automatically adjusted to different levels according to the level control signal transmitted from the base station.

Problems to be Solved by the Invention However, in this type of transmitting power secondary device that has been used in the past, a diode 104 is used to extract and detect a portion of the output of the amplifier 102, and therefore There is a problem in that when the temperature changes, the level of the detected and smoothed signal changes accordingly, making it impossible to obtain accurately specified transmission power. Therefore, as shown in U.S. Pat. No. 4,523,155 and as shown in FIG.
10° capacitor 111 is connected, and the capacitor 11
1 is provided with a temperature compensation circuit including a diode 112 and the like in the main column, and is configured to compensate for the temperature characteristics of the diode 104 by this temperature compensation circuit.

However, in this case, it is necessary to provide a separate temperature compensation circuit, and the signal applied to the other input terminal of the comparator circuit 107 simply converts the level control signal applied to the input terminal C into a D/A converter. Therefore, there was a problem in that it was relatively difficult to always accurately obtain the specified transmission power.

The present invention eliminates the above-mentioned drawbacks of the conventional technology, and aims to provide an excellent transmission power overturning device that has a simple configuration and is relatively strong against temperature changes without providing a special temperature compensation circuit. This is the purpose.

Means for Solving the Problems In order to achieve the above object, the present invention utilizes a signal applied to the input side of an amplifier as a reference AC source, and generates the reference AC source without detecting the signal amplified by the amplifier. The gain of the amplifier is automatically controlled to a gain corresponding to the level side-over signal transmitted from the base station based on the comparison result.

Therefore, according to the present invention, there is no need to use a detection diode as in the prior art, so there is no need to consider the temperature characteristics caused by the detection diode, and a transmission power overturning device that is relatively strong against temperature changes can be obtained. be able to.

Embodiment FIG. 1 is a schematic diagram of an embodiment of the transmitting force control sub-device of the present invention. In FIG. 1, a denotes an input terminal into which a high frequency signal to be transmitted is manually input.

b is an output terminal connected to an isolator or the like, and C is a side signal input terminal to which a level sterilization signal (binary encoded signal) transmitted from the base station is input. and,
1 is a gain controllable power amplifier that amplifies the high frequency signal input to the input terminal a; 2 is a capacitor that takes out a part of the high frequency signal amplified by the power amplifier 1; and 3 is a power amplifier that takes out part of the high frequency signal that has been amplified by the power amplifier 1; A differential amplifier is input to one input terminal; 4 is a phase adjuster that inputs the high frequency signal input to input terminal a and adjusts its phase; 5;
6 is a phase comparator that compares the phases of the high frequency signal whose phase has been adjusted by the phase adjuster 4 and the high frequency signal taken out via the condenser 2, and controls the phase adjuster 4 by its output; 6 is a phase comparator; The high frequency signal whose phase has been adjusted by the adjuster 4 is attenuated at a predetermined attenuation rate based on the signal transmitted from the base station and sent to the D/8 by the D/A converter circuit 7, and is then applied to the other input of the differential amplifier 3. a variable attenuator,
8 is a rectifier that rectifies the output of the differential amplifier 3.

In the above embodiment, the high frequency signal input to the input terminal a is amplified by the amplifier 1, guided to the output terminal A, and a part of it is taken out via the capacitor 2 and input to one input terminal of the differential amplifier 3. Ru. Also, before the high frequency signal input to the input terminal a is input to the amplifier 1, a part thereof is extracted and input to the phase adjuster 4. The output of the phase adjuster 4 is applied to a phase comparator 5, where its phase is compared with the high frequency signal taken out via the capacitor 2. If there is a phase difference between the two, the output controls the phase adjuster 4, and adjustment is made so that there is no phase difference between the two. The high frequency signal whose phase has been adjusted in this way is then applied to the variable attenuator 6, where it is attenuated at an attenuation rate corresponding to the level side leg signal transmitted from the base station. The attenuated high frequency signal is applied as the other input of the differential amplifier 3 and compared with the high frequency signal 2 taken out via the capacitor 2. If there is a difference between the two, the output is applied to the gain sterilization terminal of the power amplifier 1 via the rectifier 8, and the gain of the power amplifier is automatically sterilized so that the difference between the two becomes 0. . Therefore 1. J: According to the embodiment, input terminal a
By adjusting the level of the high frequency signal input to the base station to a predetermined constant value, it is possible to easily and accurately obtain the respective predetermined transmission power according to the level control signal transmitted from the base station. According to the above embodiment, after extracting the output of the amplifier, the output of the AC source serving as a reference, that is, the output of the phase adjuster 4, is directly compared with a signal only attenuated by the variable attenuator 6 without detecting it. Since the amplifier gain is set to the side by the comparison output,
There is no need to worry about the temperature characteristics of the detection diode as in the prior art, and the transmission power adjustment device can be made relatively resistant to temperature changes.

In the above embodiment, the variable attenuator 6 was provided between the phase adjuster 4 and the other input end of the differential amplifier 3.

It goes without saying that the capacitor 2 may be provided between the capacitor 2 and one input terminal of the differential amplifier 3 as shown in FIG.

Effects of the Invention As is clear from the above embodiments, the present invention utilizes a high frequency signal applied to the input side of an amplifier as a reference AC source, and compares the signal amplified by the amplifier with the reference AC source without detecting it. Based on the comparison result, the gain of the amplifier is automatically controlled to a gain corresponding to the level control signal transmitted from the base station.

Unlike conventional methods, this method does not require any detection diodes, so there is no need to consider the temperature characteristics caused by it, and the advantage is that it is possible to easily obtain a transmitter power overturning device that is relatively resistant to temperature changes. have

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of one embodiment of the transmission power control device of the present invention, FIG. 2 is a schematic configuration diagram of another embodiment, and FIG. 3 is a schematic configuration diagram of a conventional transmission power control device. It is. a...Input terminal, b...Output terminal, C...Control signal input terminal, ■...Power amplifier, 2...Capacitor,
3. Differential amplifier, 4. Phase adjuster, 5. Phase comparator,
6. Variable attenuator.

Claims (1)

[Claims] an amplifier circuit that amplifies a signal to be transmitted; a phase adjustment means that adjusts the phase of the signal taken out from the input side of the amplifier circuit so that it matches the phase of the signal taken out from the output side of the amplifier circuit; a variable attenuator that attenuates one of the phase-adjusted signals at a predetermined attenuation rate by a level control signal transmitted from the base station; A transmission power control device comprising means for comparing the other signals with each other and controlling the gain of the amplifier to a gain corresponding to a level control signal transmitted from the base station based on the comparison output.