JPH0879154A - Power control circuit - Google Patents

Abstract

PURPOSE: To provide a power control circuit simple in the configuration. CONSTITUTION: A power control circuit consists of communication equipment 1 which includes a 1st power amplifier circuit 3 that amplifies the transmission signal and also can vary its amplification factor by the control voltage and a 1st coupler 4 that monitors the output level of the transmission signal amplified by the circuit 3, and a booster 2 which is connected to the equipment 1 and includes a 2nd power amplifier circuit 15 that amplifies the output of the circuit 15 and a 2nd coupler 16 that monitors the output level of the transmission signal amplified by the circuit 15. Furthermore a 2nd switch 9 is added to select one of both detection signals which are monitored by the couplers 4 and 16, together with an error amplifier circuit 10 which amplifies the error detected by comparing the detection signal selected by the switch 9 with the reference voltage data stored previously in a memory 12. Then the amplification factor of the circuit 3 is controlled by the control voltage outputted from the circuit 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power control circuit for a wireless communication device such as a mobile phone.

[0002]

2. Description of the Related Art A mobile phone (hereinafter, also referred to as a mobile device for short) can be used by taking it outdoors, and can make a call even in a moving body such as an automobile, so that the communication is personalized and the lifestyle is diversified. In recent years, the usage has greatly increased.

In order to improve the convenience of carrying these mobile phones, it is necessary to make them compact and lightweight, but on the other hand, there are structural restrictions due to the battery capacity used, heat dissipation, etc., and their transmission output is Limited to less than 1W. Therefore, when the mobile phone is used in a car, it is not possible to secure a sufficient communication area by itself.
It has been used by expanding the communication area by connecting a power booster (power amplifier) increasing to W or 3 W to the outside. Such a mobile phone or a transmitter inside the power booster is usually controlled so that the transmission power level is changed stepwise, or a predetermined level is automatically output.
A power control circuit is provided for maintaining each. Such a booster circuit is described in, for example, Japanese Patent Laid-Open No. 3-224323 (H04B7 / 26).

[0004]

However, in the above-mentioned prior art, both the mobile phone and the booster circuit are powered by both.
In order to perform control, it was necessary to provide both sides with a power control circuit including a control circuit for controlling the transmission output. Therefore, there is a problem that the circuit scale in the power booster increases and becomes complicated.

[0005]

In order to solve the above-mentioned problems of the prior art, the present invention relates to a first power amplifier circuit capable of amplifying a transmission signal and varying the amplification factor by a control voltage, and the first power amplifier circuit. Communication device having a first coupler for monitoring the output level of the transmission signal amplified by one power amplifier circuit, and second power connected to the communication device and amplifying the output of the first power amplifier circuit In a power control circuit comprising an amplifier circuit and a booster having a second coupler for monitoring the output level of the transmission signal amplified by the second power amplifier circuit, the output signal of the first power amplifier circuit is an antenna. Alternatively, a first switch selectively supplying one of the second power amplifier circuits and the first and second couplers are used. A second switch that selects either one of the detected signals that have been perturbed, and an error amplifier that amplifies the error by comparing the detection signal selected by the second switch with the reference voltage data stored in advance in the memory. Circuit, and the amplification factor of the first power amplifier circuit is controlled by a control voltage output from the error amplification circuit.

Further, the power control circuit according to the present invention is provided with level adjusting means for adjusting the second coupler output power, and when the communication device is used alone and when the booster is connected to the communication device in series. By making the input level of the second switch the same as that at the time, the power control reference voltage data stored in the memory is shared.

Further, according to the present invention, each of the first and second detection circuits for detecting the output signals of the first and second couplers and converting the output signals into a DC voltage is provided, and the level adjusting means is used to provide the second signal. It is characterized in that the level of the detection circuit output signal is adjusted.

Further, the present invention is characterized in that the level adjusting means is configured by making the coupling degree of the second coupler different from the coupling degree of the first coupler.

[0009]

According to the first aspect of the present invention, when the communication device is used alone, the detection signal monitored by the first coupler is also used by connecting the booster to the communication device. In this case, the detection signal monitored by the second coupler is selected by the second switch, and the power amplifier is based on the result of comparison with the reference voltage stored in the memory of the communication device by the error amplification circuit. The amplification factor of is controlled.

According to the second aspect of the present invention, the second switch input level is set by the level adjusting means when the communication device is used alone and when the booster is connected to the communication device in series. The number of reference voltage data for power control, which are adjusted in the same manner and stored in the memory, is reduced.

According to the third aspect of the invention, since the level adjustment is performed after the RF signal output from the coupler is converted into the DC voltage by the detection circuit, the level adjustment means can be realized with a simple configuration. .

[0012] According to the invention of claim 4, the second
The level is adjusted by the coupler.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A power control circuit according to the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of a power control circuit according to the present invention, and is a block diagram when a power booster is connected to a mobile phone in an automobile or the like. The mobile phone 1 is on the left side of the alternate long and short dash line, and the power booster 2 is on the right side. 3 is a power amplifier circuit that amplifies a transmission RF signal, 4
Is a coupler having a coupling degree of 10 to 20 dB, 5 is a switch for selectively transmitting a transmission RF signal to either the portable device antenna 6 built in the mobile phone 1 or the power booster 2 via the terminal 7, 8 Is a detection circuit for detecting the level of the RF signal transmitted from the coupler 4, 9 is a switch, 10 is an error amplification circuit, and 11 is a control circuit for controlling the output based on a later-described reference voltage Vref stored in the ROM 12. The detection circuit 8, the control circuit 11, and the error amplification circuit 10 form a feedback loop for controlling a transmission output described later.

Reference numeral 13 is a detection circuit for detecting whether or not the mobile phone 1 is connected to the power booster 2. Based on the detection result of the detection circuit 13, the switch 5 and the switch 9 are switched and the control circuit 11 is controlled. Also sends the detection result. That is, when the mobile phone 1 is used alone and the power booster 2 is not connected, the switch 5 and the switch 9 are on the contact a side, and when the mobile phone 1 and the power booster 2 are connected, the switch 5 and the switch 5 are The switch 9 is switched to the contact b side. When the switch 5 is on the contact a side, transmission / reception is carried out by the portable device antenna 6 built in the mobile phone 1, and when the switch 4 is switched to the contact b side, the transmission signal is transmitted from the terminal 7 to the power booster 2 And is transmitted from the vehicle-mounted antenna 14 mounted outside the vehicle.

Like the mobile phone 1, the power booster 2 is also provided with a power amplifier circuit 15, a coupler 16 and a detection circuit 17, and the detection output of the detection circuit 17 is sent to the mobile phone 1 via a control terminal 18.

Next, the operation will be described. When the mobile phone 1 is used alone, the detection circuit 13 switches the switch 5 and the switch 9 to the contact a side. After the transmission RF signal is amplified by the power amplifier circuit 3, the coupler 4 outputs transmission signal power obtained by subtracting the coupling degree from the coupling output end. This RF signal level is envelope-detected by the detection circuit 8 in the next stage consisting of a diode, a resistor and a capacitor, converted into a DC voltage VDC and sent to the error amplification circuit 10 via a switch 9. Output VDC of detection circuit 8
Is compared with a reference voltage Vref generated by the control circuit 11 based on the ROM 12, and the output voltage VCONT of the error amplification circuit 10 changes according to the error. Further, the output of the error amplifier circuit 10 is fed back to the voltage control terminal of the power amplifier circuit 3, and the output level is controlled by increasing or decreasing the amplification factor of the power amplifier circuit 3.
Therefore, by controlling the reference voltage Vref generated by the control circuit 11, a transmission output corresponding to the Vref level is obtained and is transmitted from the portable device antenna 6 via the switch 5. Once Vref is fixed, the level is automatically stabilized by the feedback loop so that the transmission output is always constant, and the transmission output is held at a constant value.

Here, the control width and range of the power control circuit differ depending on the mobile station type. For example, in the domestic digital mobile phone system, the maximum output is 0.8
In mobile station type III with W, maximum is 2 with 4 dB step width.
It is regulated to 0 dB. Similarly, mobile station type I
(Maximum output: 3W) 28 at maximum with the same control step width
Up to dB, the mobile station type II (maximum output: 2 W) is regulated to control up to 24 dB with the same control step width.

Based on this, the reference voltage Vref is determined as shown in FIG. 2 according to each usage pattern of the portable device single use and the booster connection use, and is stored in the ROM 12. In other words, there are a total of 14 levels: 6 levels when using a portable device alone (for mobile station type III) and 8 levels when using a power booster (for mobile station type I).
The data of each Vref is stored.

When the mobile station type I is obtained by connecting the power booster, the maximum transmission level control range is 28d.
It becomes B and is controlled by the following operation. When the power booster 2 is used by connecting to the mobile phone 1, the detection circuit 13 is used.
When it is detected that the power booster 2 is connected, the switches 5 and 9 are switched to the contact b side,
The power amplifier circuit 3 is controlled by the detection output of the detection circuit 17 on the power booster 2 side, and power control is performed by a large feedback loop including the power booster.

That is, the transmission signal from the mobile phone 1 is sent to the power booster 2 via the terminal 7, and is sent from the vehicle-mounted antenna 14 via the power amplifier circuit 15 and the coupler 16. At this time, the detection circuit 1 of the power booster 2
The detection output detected by 7 is sent to the error amplification circuit 10 as VDC via the control terminal 18 and the switch 9. On the other hand, the control circuit 11 reads the reference voltage when the booster connection is used from the ROM 12, sends it as Vref to the error amplification circuit 10, and the transmission signal power is controlled based on this.

In this embodiment, the power booster 2
It is not necessary to provide a control circuit in, and the configuration is simple.

FIG. 3 is a block diagram showing a second embodiment. The same components as those in FIG. 1 are designated by the same reference numerals and their description will be omitted. The difference from the first embodiment is that a level adjusting circuit 19 for adjusting the level of the RF output output from the coupler 16 of the power booster 2 is provided. In the first embodiment, the presence or absence of the connection between the portable device 1 and the power booster 2 is detected, and a total of 14 units are used when the portable device is used alone and when the power booster is connected to the portable device. Although it is necessary to store the power control reference voltage Vref data in the ROM 12, the second embodiment reduces the ROM capacity. In the power booster 2, the signal supplied from the mobile phone 1 side is amplified by the power amplifier circuit 15 and input to the coupler 16. The output RF signal of the coupler 16 is transmitted via the vehicle-mounted antenna 14.
The signal level of the coupler 16 combined output signal is adjusted by a level adjusting circuit 19 such as an attenuator, fed back to the mobile phone 1 and supplied to the input terminal of the switch 9 on the b side.

In the detection circuit 8 at the next stage, the monitor signal from the switch 9 is subjected to envelope detection to generate a detection DC voltage VDC. The output of this detection circuit 8 is output by the error amplification circuit 10.
Based on the ROM 12, the reference voltage Vref generated in the control circuit 11 is compared with VDC, and the output voltage VCONT of the error amplifier circuit 10 changes according to the error.

The output of this error amplifier circuit 10 is fed back to the voltage control terminal of the power amplifier circuit, and the power is increased by increasing or decreasing the amplification factor of the power amplifier circuit.
The transmission signal level at the star output end is controlled stably.

Therefore, by controlling the reference voltage Vref generated by the control circuit 11, a transmission output corresponding to the Vref level is sent out from the vehicle-mounted antenna 111 and power control is performed.

Here, the level adjusting circuit 19 adjusts the output level of the coupling terminal of the coupler 16. That is, when the power output from the power booster is 3 W (type I of mobile station), the output level of the coupling terminal is attenuated by a certain amount by an attenuator, for example. The amount of this attenuation is determined by the feedback input level to the terminal b of the switch 8 in the mobile phone and the output from the coupling terminal of the coupler 4 when the output power of the mobile device when the mobile device is used alone is 0.8 W. The input level to a is set to the same value. At this time, the power control reference voltage Vref output from the control circuit 11 is, for example, 3.
16V is generated and input to the non-inverting input terminal of the error amplifier circuit 10.

FIG. 4 shows a power control stored in the ROM 12, which is generated when the portable device is used alone (mobile station type III) and when the power booster is connected (mobile station type I). 3 shows a reference voltage for ref.
Maximum output (0.8 W and 3 W), -4 dB control (0.
8W-4dB and 3W-4dB), ..., The reference voltage Vref generated during -20dB control (0.8W-20dB and 3W-20dB) is 3.16V, 2.92V, respectively.
... 1.98V, which is commonly used when the portable device is used alone and when the power booster is connected. In this example, the ROM
It is sufficient to store 8 pieces of data as the power control reference voltage in 12, and the memory capacity can be reduced by 6 as compared with the first embodiment.

FIG. 5 is a block diagram showing a third embodiment of the present invention. In FIG. 5, the coupler 4 and the coupler 1
The output of the coupling terminal 6 is the detection circuit 8 and the detection circuit 20 respectively.
Then, the envelope curve is once detected and converted into a DC voltage. Further, the output of the detection circuit 20 is adjusted by the DC voltage level adjusting circuit 21 so that the input DC levels to the terminals a and b of the switch 9 become the same. After that, the first operation
The description is omitted because it is the same as the second embodiment.
According to the third embodiment, the level adjustment circuit 21 adjusts the DC voltage output from the detection circuit 20, so that the level adjustment circuit 21 shown in FIG.
The configuration of the level adjusting circuit becomes extremely simple as compared with the second embodiment shown in FIG.

FIG. 6 shows a fourth embodiment of the present invention. In FIG. 6, the coupling degree of each of the coupler 4 and the coupler 22 is different. That is, for example, the coupler 4 is tightly coupled and the coupler 22 is coarsely coupled. The difference in coupling degree between the two is equivalent to the amount of attenuation of the level adjusting circuit 19 in the second embodiment shown in FIG. 3, and by using the couplers having such different coupling degrees, the terminal a of the switch 9 and the The input signals to the terminal b are at the same level.

In FIG. 6, the coupler output RF signal is inputted to the detection circuit 8 via the switch 9. However, the coupled output of the coupler 4 and the coupler 2 are the same as in the third embodiment of FIG.
It is also possible to have a configuration in which the two combined outputs are respectively passed through a detection circuit and then both detection output signals are switched by a switch.

[0031]

As described above, according to the present invention, since the power control is performed by the communication device, it is not necessary to provide a control circuit such as a CPU for controlling the transmission output in the booster, and the structure is improved. A simple power control circuit can be realized.

Further, in the transmission power control circuit of the portable device and the power booster connected thereto by the level adjusting means, the reference voltage data for power control required when the portable device alone is used and when the power booster is connected.
Since the data can be shared by the portable devices, the circuit inside the power booster can be simplified. In addition, the memory capacity in the portable device can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing stored contents of a ROM 12 used in the first embodiment of the present invention.

FIG. 3 is a block diagram showing a second embodiment of the present invention.

FIG. 4 is a diagram showing stored contents of a ROM 12 used in a second embodiment of the present invention.

FIG. 5 is a block diagram showing a third embodiment of the present invention.

FIG. 6 is a block diagram showing a fourth embodiment of the present invention.

[Explanation of symbols]

 1 Mobile Phone (Communication Device) 2 Power Booster 3 First Power Amplifier Circuit 4 First Coupler 5 First Switch 6 Antenna 8 Detection Circuit 9 Second Switch 10 Error Amplification Circuit 11 Control Circuit 12 ROM (Memory) 14 Antenna 15 Second power amplifier circuit 16 Second coupler 19 Level adjusting circuit 20 Detection circuit 21 Level adjusting circuit 22 Coupler as level adjusting means

Claims (4)

[Claims] 1. A first power amplifier circuit capable of amplifying a transmission signal and varying an amplification factor by a control voltage, and a first power amplifier circuit monitoring the output level of the transmission signal amplified by the first power amplifier circuit. Device having a coupler, a second power amplifier circuit connected to the communication device for amplifying an output of the first power amplifier circuit, and an output level of a transmission signal amplified by the second power amplifier circuit. In a power control circuit comprising a booster having a second coupler for monitoring the first power amplifier circuit, the output signal of the first power amplifier circuit is selectively supplied to either the antenna or the second power amplifier circuit. Switch and a second switch for selecting one of the detection signals monitored by the first and second couplers. And an error amplification circuit for performing error amplification by comparing the detection signal selected by the second switch with reference voltage data stored in advance in the memory. The control voltage output from the error amplification circuit A power control circuit for controlling the amplification factor of the first power amplifier circuit. 2. The power control circuit according to claim 1, further comprising level adjusting means for adjusting the output power of the second coupler, when the communication device is used alone and when the booster is connected in series to the communication device. The power control circuit is characterized in that the reference voltage data for power control stored in the memory is shared by adjusting the input level of the second switch to be the same as when it is connected to. 3. The power control circuit according to claim 2, further comprising first and second detection circuits for detecting the output signals of the first and second couplers and converting the output signals into a DC voltage, and adjusting the level. A power control circuit, wherein the level of the output signal of the second detection circuit is adjusted by means. 4. The power control circuit according to claim 2, wherein the level adjusting means is configured by making the coupling degree of the second coupler different from the coupling degree of the first coupler. Power control circuit.