JPH03117929A - Automatic power controller - Google Patents

Abstract

PURPOSE:To reduce the fluctuation of transmission output due to temperature change and to prevent the increase of the power loss by providing plural directional couplers, which mutually have parallel relations and are different in degree of coupling, and a means which alternatively activates these directional couplers. CONSTITUTION:When a high transmission output will be set, a microcomputer 26 outputs a switch control signal 28 to turn on and off switches 35a and 35b respectively. That is, first directional couplers (29, 30a, and 34a) having a low degree of coupling are selected. When a low transmission output will be set, the microcomputer 26 outputs the switch control signal 28 to turn on and off switches 35b and 35a respectively. That is, second directional couplers (29, 30b, and 34b) having a high degree of coupling are selected. Thus, the transmission output variance is evaded and the increase of the power loss is evaded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to an automatic power control device suitable for controlling the transmission output power of a radio telephone device.

(Prior Art) FIG. 3 is a block diagram showing the configuration of an automatic output control circuit (APC) conventionally employed at the final stage of a wireless telephone device.

As shown in the figure, this automatic output control circuit connects the output of a high frequency power amplifier 1 to a strip line 2. It is taken out through a directional coupler consisting of a pickup line 3 coupled to this and a terminating resistor 4 of this pickup line 3, and is also taken out through a diode rectifier 5 and a smoothing filter (consisting of a capacitor 6 and a resistor 7). The DC voltage value obtained by this conversion is converted into a DC voltage value (
10 supplied from the microcomputer 9, and the gain of the high frequency power amplifier 1 is changed so that the deviation between them becomes zero.

In the figure, 11 is a voltage controller, and 12 is a bandpass filter for removing unnecessary power.

However, in such conventional automatic power control devices, when it is necessary to switch the transmission power in multiple stages, the strip line 2. If the coupling degree of the directional coupler composed of the pickup line 3 and the terminating resistor 4 is weak,
There is no problem when the transmission power is large, but when the transmission power is small, the power appearing on the pickup line 3 is also small, so that it is easily influenced by the forward voltage of the diode 5, as shown in the following equation.

VREF −Vdet −K −VFVREP,
Voltage rectified by the diode Vdet; pickup voltage of the directional coupler; rectification efficiency VF of the diode, forward voltage of the diode In this way, the influence of the forward voltage of the diode becomes easier, as shown in Figure 4. As shown, the forward voltage VF
varies with temperature, so diode 5
The rectified voltage V RIEI' changes, and the transmission power also changes due to the influence of temperature.

Furthermore, if the degree of coupling of the directional coupler is strong, the influence of temperature will not be much of a problem when the transmission power is small, but on the other hand, the power loss in the directional coupler itself will increase. That is, if the power at the antenna end is constant regardless of the degree of coupling of the directional coupler, there is a problem in that the stronger the degree of coupling of the directional coupler, the greater the power loss.

(Problem to be Solved by the Invention) As mentioned above, in the conventional automatic output control circuit, when it is necessary to switch the transmission power in multiple stages, the weak coupling of the directional coupler causes particularly low transmission. There was a problem in that the fluctuation of the transmission output becomes large during output, and if the degree of coupling of the directional coupler is strong, the insertion loss in the directional coupler becomes large especially when the transmission output is high, resulting in an increase in power loss. .

This invention was made in view of the above problems,
The purpose is to provide an automatic power control device that has little variation in transmission output due to temperature even when the transmission output is low, and that does not increase power loss in the directional coupler even when the transmission output is high. .

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention connects the output of a high frequency power amplifier to a strip line interposed between the output end of this amplifier and an antenna.

This is taken out through a directional coupler consisting of a pickup line coupled to this and a terminating resistor of this pickup line, and is converted to a DC voltage through a diode rectifier and a smoothing filter.The DC voltage obtained by this conversion is In an automatic power control device that compares a voltage value with a DC voltage value corresponding to a control 11 standard power value, and changes the gain of the high frequency power amplifier so that the deviation between them becomes zero, there is a mutually parallel relationship. The present invention is characterized by comprising a plurality of directional couplers having different degrees of coupling and means for selectively activating these directional couplers.

(Function) According to such a configuration, when it is necessary to switch the transmission power in multiple stages, for example, when the transmission power is low, a directional coupler with a strong coupling degree is selected to avoid fluctuations in the transmission power. Moreover, when the transmission power is high, by selecting a directional coupler with a weak coupling degree, an increase in power loss can be avoided.

(Embodiment) FIG. 1 is a block diagram showing the configuration of an embodiment of an automatic power control device according to the present invention.

In the figure, two directional couplers, which are essential parts of the present invention, are provided between the output end of the high frequency power amplifier 1 and the antenna 23.

That is, strip line 29. The pickup line 30a with a weak coupling degree and the terminating resistor 34a constitute a first directional coupler with a weak coupling degree, and two strip lines and the pickup line 30 with a strong coupling degree are configured.
b and the terminating resistor 34b constitute a second directional coupler with strong coupling.

These first. The second directional coupler includes a switch 35a,
It is selectively activated by turning on or off 35b.

The output of the first directional coupler is converted to a DC voltage Va through a rectifier consisting of a diode 33a, a smoothing circuit consisting of a resistor 31a, and a capacitor 32a, and the output of the second directional coupler is converted from a diode 33b to a smoothing circuit consisting of a resistor 31a and a capacitor 32a. The voltage is converted into a DC voltage Vb through a smoothing circuit including a rectifier, a resistor 31b, and a capacitor 32b.

The DC voltages Va and Vb obtained by these conversions are applied to the common comparator 25 according to the operation of the switches 35a and 35b.
will be introduced to.

Then, as in the conventional example, the voltage controller 24 is operated by the output of the comparator 25, and the voltage controller 24 is operated by the output of the comparator 25.
4 controls the gain of the high frequency power amplifier 21.

In the figure, 22 is a band pass filter for removing unnecessary power, and 26 is a microcomputer.

Next, the operation of the automatic power control device having the above configuration will be systematically explained.

When setting high transmission output, microcomputer 2
6, it applies a corresponding voltage as the reference voltage V ref' and outputs the switch control signal 28 to turn on the switch 35a and turn off the switch 35b, as shown in FIG.

Then, the first directional coupler (29, 30
a, 34a) is selected, power loss can be reduced.

On the other hand, when setting a low transmission output, the microcomputer 26 applies the corresponding voltage as the reference voltage V ref' and outputs the switch control signal 28 to control the switch 35b as shown in FIG. is turned on and switch 35a is turned off.

Then, the second directional coupler (29, 30
b, 34b) is selected to reduce transmission power fluctuations due to temperature.

As described above, this embodiment has the advantage that there is little variation in the transmission output due to temperature even when the transmission output is low, and power loss in the directional coupler does not increase even when the transmission output is high.

Although the present invention has been applied to a wireless telephone device in the above embodiments, it is of course applicable to various other wireless transceivers.

〔Effect of the invention〕

As is clear from the above explanation, according to the present invention, even when the transmission output is low, there is little variation in the transmission output due to temperature.
Furthermore, it is possible to provide an automatic power control device that prevents power loss in the directional coupler from increasing even when the transmission output is high.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the configuration of the automatic power control device according to the present invention, Fig. 2 is a diagram showing the difference in the operating state of the switch when the transmission output is high and low, and Fig. 3 is a diagram showing the difference in the operating state of the switch when the transmission output is high and low. FIG. 2 is a block diagram showing an example. 21... High frequency power amplifier, 22... Band pass filter, 23... Antenna, 24... Voltage controller,
25... Comparator, 26... Microcomputer,
28...Switch control signal, 29...Strip line, 30a...Pickup line with weak coupling degree,
30b...Pickup line with strong coupling, 34
a. 34b...terminal resistor, 35a, 35b...switch. Figure 2 Figure 4 Procedure moss 1ff official book (method) % formula % Display of case Relationship to 1999 Patent Application No. 256696 Patent applicant (307) Toshiba Corporation Toshiba Corporation (104) Chuo, Tokyo 6th floor, Ginza Daisaku Building, 2-11-2, Ginza, Ward Telephone: 03-545-3508 (Representative) December 27, 1999 (Start gate: January 30, 1990) 7. Contents of the amendment Description of the claimed invention , page 11, lines 8 to 9, ``Figure 3 is a block diagram showing an example of a conventional device.''
Correct as shown below. ``Figure 3 is a block diagram showing an example of a conventional device, and Figure 4 is a diagram showing the voltage versus current characteristics of a diode.''

Claims (1)

[Claims] (1) A part of the output of the high-frequency power amplifier is transferred to a strip line interposed between the output end of the amplifier and the antenna, a pickup line coupled to the strip line, and a terminating resistor of the pickup line. This is extracted through a directional coupler consisting of a diode rectifier and a smoothing filter, and converted into a DC voltage. The automatic power control device changes the gain of the high frequency power amplifier so that the deviation thereof becomes zero, comprising: a plurality of directional couplers that are in a parallel relationship with each other and have different degrees of coupling; An automatic power control device characterized by comprising means for selectively activating these directional couplers. (2) an amplifying means for amplifying an input high frequency signal; a plurality of coupling means having different degrees of coupling for extracting at least a part of the output signal of the amplifying means; and an output signal of each of the coupling means. An automatic power control device comprising: an adjustment means for selectively selecting one output signal and adjusting the amplification degree of the amplification means based on the selected output signal. (3) The automatic power source according to claim (2), wherein the plurality of coupling means are a first directional coupler and a second directional coupler arranged in parallel to the output line of the amplification means. Control device. (4) The automatic power control device according to claim (3), wherein the first directional coupler has a higher degree of coupling than the second directional coupler. (5) The automatic power control device according to claim (2), wherein the adjustment means selects one of the output signals of the plurality of coupling means based on the required transmission power. (6) The automatic power control device according to claim (5), wherein the adjustment means compares a level control signal supplied from the outside with an output signal of the selected coupling means.