JPS61121536A - Control circuit for transmission power - Google Patents

Abstract

PURPOSE:To keep an approximately fixed level of electric power applied to a wave detecting part between large and small power modes, by extracting a partial output of a power amplifying part through plural detecting parts and connecting the extracted output to the wave detecting part after switching it. CONSTITUTION:The partial output of a power amplifying part 1 is extracted by detecting parts 51 and 52 via a strip line 6. In a large power mode, a command given from a base, a command obtained from the reception field information or the control signal obtained from said field information is supplied through a terminal 14. Then a switching part 12 is operated for selection of the part 51. While in a small power mode the part 12 selects the part 52 with an indication given from a power control signal generating part 13. Thus an approximately fixed level of electric power is applied to a wave detecting part 4 between the large and small power modes. An error detecting part 3 detects the difference between the DC voltage delivered from the part 4 and the reference voltage given from the part 13. A power supply voltage control part 2 is controlled by said error detection signal and the power supply voltage of the amplifier 1 is controlled via the part 2. Then the output of the amplifier 1 is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Applicability) The present invention relates to a transmission power control circuit for a transmitter that can be used in a mobile communication device.

(Prior art) In recent mobile communication devices, when communicating with a base station or a mobile communication device, the transmission power is changed according to the strength of the Kt field to prevent mutual modulation and cross-modulation. It's starting to look like this. The power level that is changed is typically between 1GdB and 30
dB, for example, if the transmission output is 10W, 1
m Vary the feed level from W to IW.

Conventionally, transmission power has been controlled by varying the amount of attenuation of an attenuation device attached to the output side of a transmitter or by varying the power supply voltage of an amplifier.

However, the former method requires an expensive attenuation device, and the latter method directly affects the output power characteristics from the frequency characteristics and temperature characteristics of the power amplifier, so the method shown in FIG. 3 has also been adopted. In Fig. 3, 1 is a power amplification section, 2 is a power supply voltage control section, 3 is an error amplification section, 4 is a detection section, 5 is a detection section, and 6
is a strip line, 7 is an isolator, and 8 is an antenna. In FIG. 3, a part of the output power amplified by the power amplifying section 1 is taken out from the strip line 6 through the detecting section 5. Next, the extracted minute power is converted into a Do voltage (Vd') by the detection section 4. Furthermore, the reference voltage (Vref) inputted through the base single voltage input terminal,
The Do voltage (Vd) is compared with the Do voltage (Vd) by the error amplification section 3, and the error voltage is amplified by the error amplification section 3. Furthermore, the error signal amplified by the error amplification section 3 controls the power supply voltage control section 2 to control the power supply voltage or input power of the power amplification section 1 to control the output voltage. Here, the detecting section 5 is generally formed by forming a coupler using the strip line 6 or by forming a capacitor.

(Problems to be Solved by the Invention) If the above method is adopted, an expensive attenuator is unnecessary and it is less likely to be affected by the characteristics of the amplifier.

However, in the above method, when the detection unit 4 attempts to obtain a detected voltage vd of 0.5 to 1 V at the minimum power for a variable power amount of 30 dB, the detected voltage at the maximum power is 15 to 1 V.
It becomes oV. In mobile communication devices, the power supply voltage is mainly 1zV system, so unless z4V system is created inside the device,
The error amplifier has a drawback in that it cannot compensate for voltages up to 15-zoV.

Another possible method is to insert a variable attenuator between the detection section 4 and the error amplification section 3 and to vary the attenuator depending on the power. Even if the method of inserting the variable attenuator is used as described above, the detection section must process a large voltage.
The drawback was that the detection diodes and the like were required to have high voltage resistance. Furthermore, since the high-frequency impedance of the detection section changes between low power and high power, there is also a drawback that the power deviation within the band becomes large at low power. For example, even if the power deviation at high power in the 800MHz band is ±0.5 dB, it is ±1,0 dll at low power.
It has the disadvantage of being magnified by 1C4. Furthermore, handling a large amount of high-frequency power in the detection section 4 has the disadvantage that distortion occurs in the detection diode, and the harmonics are radiated back to the antenna system through the coupler that was generating the harmonics.

An object of the present invention is to eliminate the above-mentioned drawbacks by providing two or more detection sections having different degrees of coupling and a changeover switch between the detection section and an error amplifier, and to An object of the present invention is to provide a power control circuit configured to suppress the power applied to the detection section to approximately constant by changing the ratio of power extracted from the detection section.

(Means for Solving the Problems) A transmission power control circuit according to the present invention includes a power amplification section, a plurality of detection sections, a changeover switch, a detection section, an error amplification section, and a power supply voltage control section. However, the transmission power is maintained at a specified value within the power range selected by the changeover switch.

The power amplification section is for generating transmission power, the plurality of detection sections are for extracting a part of the power sent to the antenna from the power amplification section, and the changeover switch is for generating a plurality of detection sections. The detector is for selecting one of the powers detected by the switch, and the detector is for converting the power sent from the changeover switch into a DC voltage.

The error amplification section is for comparing the DC voltage obtained from the detection section with a reference voltage and sending out an error signal from the specified power.

The power supply voltage control section is for controlling the power supply voltage of the power amplification section using the error signal obtained from the error amplification section.

(Example) Next, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the basic configuration of a transmission power control circuit according to the present invention.

In FIG. 1, 1 is a power amplification section, 2 is a wL power supply voltage control section, 3 is an error amplification section, 4 is a detection section, 51 and 52 are respective detection sections, 6 is a strip line, 7 is an isolator,
8 is an antenna, 9 is a high frequency signal input terminal, IO is a power supply terminal, 12 is a switching section, 13 is a power control signal generation section, 14
is a control signal input terminal.

In Fig. 1, in the detection units 51 and 52, the one with the smaller coupling degree is ``1m'', and the thicker b side is 52.When the power is high, commands from the base or control signals from received electric field information are sent to the terminal 14. input from above and operate the switching unit 12 to select the detection unit 51. When the power is small, the switching unit 12 selects the detection unit 52 according to the instruction from the power control signal generation unit 13. The above operation allows the detection output For example, the amount of voltage change is within the range of about 1 to 5 V for a variable amount of power of 30 dB, and the deviation of the power level within the band is also improved when the power level is low.

FIG. 2 is a block diagram showing an embodiment embodying the principle of FIG. 1. In Figure 2, the same elements as in Figure 1 are given the same numbers, 15 is a coaxial relay, 16 is a detection diode, 17 is a resistor, 18 is a capacitor, 1
91 and 192 are connecting bats, respectively. The detection units 51 and 52 have different distances from the strip line 6 (parameters) 191 and 1512 K, respectively, thereby forming capacitances.

The switching section 12 is configured using a coaxial relay 15, and the detection section 4 is configured using a detection diode 16, a capacitor 18, and a resistor 17.

The above explanation is an example in which only two detection sections are switched and used, but it is possible to cope with an even wider dynamic range by providing three or even four detection sections with different degrees of coupling. Not even.

(Effects of the Invention) As explained above, in the present invention, the degree of coupling between the stripline and the detection section is changed according to the power, and the power input to the detector is kept constant. Even in a transmitting device with a large amount of power, large high frequency distortion does not occur in the detection section, and even if there is distortion, it is suppressed from being transmitted to the antenna via the power detection section. Furthermore, since the input voltage to the error amplifier is suppressed to a relatively small range, there is an effect that a DC voltage conversion device is not required.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic configuration of a transmission power control circuit according to the present invention. FIG. 2 is a block diagram showing an embodiment of a transmission power control circuit according to the present invention. FIG. 3 is a block diagram showing a series of transmission power control circuits according to the prior art. 1... Power amplifier section 2... Power supply voltage control section 3...
- Error amplification section 4... Detection section 51, 52... Detection section 6... Strip line 7... Isolator 8... Antenna 12... Switching section 13.
...Power control signal generator 15...Coaxial relay 16
...Diode 17...Resistor 1B...Capacitor 191, 192...Pad

Claims (1)

[Claims] a power amplifying section for generating transmission power; a plurality of detecting sections for extracting a part of the power sent to the antenna from the power amplifying section; and one of the powers detected by the plurality of detecting sections. A changeover switch for selection, a detection section for converting the power sent from the changeover switch into a DC voltage, and a detection section that compares the DC voltage obtained from the detection section with a reference voltage to determine the difference from the specified power. an error amplification section for sending out an error signal; and a power supply voltage control section for controlling a power supply voltage of the power amplification section using the error signal obtained from the error amplification section, the power supply voltage control section being selected by the changeover switch. A transmission power control circuit characterized in that the transmission power is maintained at a specified value within a power range set by the transmission power control circuit.