JPH08265210A - High frequency radio transmitter - Google Patents

Abstract

PURPOSE: To stabilize a line connection rate without depending on the using channel by outputting fixed output power from an antenna output terminal over the entire using channels. CONSTITUTION: Output control data including a correction value for indicating the relation of the output power passing loss of a directional coupler 2 and the using channel are stored in a memory 9 beforehand. When the using channel is set for transmission, a CPU 10 reads the output control data corresponding to the using channel and outputs control signals S10. The control signals S10 are converted to analog reference signals S11 in a D/A converter 11. The output power of a power amplifier 1 is detected in the directional coupler 2 and a detection diode 5 and detection signals S5 are outputted. The reference signals S11 and the detection signals S5 are compared in an operation amplifier 6 and the output power of the power amplifier 1 is controlled through a transistor 8 based on the compared result. The output power is branched and filtered from reception radio waves in a transmission/reception branching filter 3 and then, outputted from an antenna 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio frequency radio transmitter such as a car telephone unit or a mobile telephone unit, and more particularly to an output control system of its power amplifier.

[0002]

2. Description of the Related Art Conventionally, in a transmitter of a high frequency radio transmitter, the power of a modulated transmission signal is amplified by a power amplifier, and the output power of the power amplifier is sent to an antenna via a duplexer, and the antenna is transmitted. It emits radio waves transmitted from. An output control circuit is feedback-connected between the output terminal and the power control terminal of the power amplifier. When the output power of the power amplifier fluctuates, the fluctuation is detected by the output control circuit, and a feedback signal for canceling the fluctuation of the output is given to the power control terminal of the power amplifier so that the power amplifier always maintains a constant value. It is designed to deliver output power. On the other hand, the received radio wave is received by the antenna, demultiplexed with the transmission radio wave by the transmission / reception demultiplexer, and then sent to the receiving unit side for reception processing. The transmission / reception duplexer is composed of, for example, a transmission filter, a reception filter, and a demultiplexing circuit. Since one antenna is used for transmission / reception, the transmission / reception filter and the antenna are impedance-matched. The transmission filter and the reception filter are formed of, for example, dielectric filters made of dielectric ceramics that can be miniaturized. The equivalent circuit of this transmission / reception filter is composed of an inductance L and a capacitance C.

[0003]

However, the conventional high-frequency radio transmitter has the following problems and it is difficult to solve them. In the output section of the conventional high-frequency wireless transmitter, in order to prevent a communication failure due to a decrease in the output power from the antenna and a decrease in the line connection rate, feedback control of the output power of the power amplifier is performed by the output control circuit. As a result, a constant output power is always sent from the power amplifier. However, between the output terminal of the power amplifier and the output terminal of the antenna, there is a pass loss such as a duplexer, and the pass loss depends on the use frequency band (use channel) of the high frequency wireless transmission device. The output power at the output end of the antenna is not constant and varies depending on the channel used. Therefore, in actual use of the high frequency wireless transmitter, the line connection rate in the used frequency band (used channel) is affected (the line connection rate is lowered). As a method of preventing such a decrease in the line connection rate, for example, a directional coupler is inserted between the transmission / reception demultiplexer and the antenna, the output power is detected by the directional coupler, and it is determined that the output power is constant. A method of applying feedback to the power control terminal of the power amplifier is also considered. However, if a directional coupler is inserted between the transmission / reception demultiplexer and the antenna, the impedance matching between the transmission / reception filter forming the transmission / reception demultiplexer and the antenna may not be achieved, which may adversely affect the reception system. It is hard to adopt because it can be done. Therefore, it has been difficult to provide a power amplifier output control technology that is still technically sufficiently satisfactory.

[0004]

In order to solve the above-mentioned problems, the first aspect of the present invention is to amplify the power of a high-frequency transmission signal at a level according to a control signal in an output section of a high-frequency radio transmission device. An output power amplifier, an antenna that radiates the output power in the form of a transmission radio wave and receives a reception radio wave, an output power of the power amplifier that is sent to the antenna, and a reception radio wave that is received by the antenna A power detecting unit that is connected between the power amplifier and the transmission / reception demultiplexer for separating and inputting to the receiving unit side and detecting the output power of the power amplifier and outputting a detection signal. And a memory. The memory includes a correction value indicating a relationship between an output power passage loss from the output side of the power amplifier to the antenna output end and a use channel that is a use frequency band, and outputs the use channel and the antenna output end. The storage device stores output control data indicating a relationship with an output power value to be output. Further, in the first aspect of the present invention, when a use channel is set during transmission, a memory access unit that reads out the output control data corresponding to the use channel from the memory and outputs a reference signal, the detection signal and the Comparison control means is provided for applying the control signal to the power amplifier for comparing the reference signal and changing the detection signal so that the level difference between the two signals becomes zero. According to a second aspect of the invention, in the radio frequency transmitter of the first aspect of the invention, the power detection means includes a directional coupler that extracts the output power of the power amplifier and a detection diode that detects the output signal of the directional coupler. I am configuring. The memory access means includes a central processing unit (hereinafter, referred to as CPU) that controls reading and writing of a memory, and a digital / analog converter (hereinafter, referred to as a CPU) that converts an output digital signal of the CPU into an analog reference signal.
D / A converter). Further, the comparison control means compares the detection signal output from the detection diode with the reference signal output from the D / A converter, and changes the detection signal so that the level difference between the two signals becomes zero. And an operational amplifier for controlling the output power of the power amplifier by outputting a control signal of a level corresponding to the output signal of the operational amplifier.

[0005]

According to the first and second aspects of the invention, since the high frequency radio transmitter is constructed as described above, when transmitting with a certain use channel, when the use channel is set, the memory access means uses the use channel. The output control data corresponding to the channel is read from the memory and the reference signal is output. On the other hand, the output power of the power amplifier is detected by the power detection means, and the detection signal is output from the power detection means. The comparison control means compares the reference signal with the detection signal, and the comparison control means controls the output power of the power amplifier so that the level difference between the two signals becomes zero.
The output power of this power amplifier is output from the antenna output end after being demultiplexed from the received radio wave by the transmission / reception duplexer through the power detection means. The output control data stored in the memory contains a correction value that indicates the relationship between the output power passage loss from the output side of the power amplifier to the antenna output end and the channel used, so the antenna output end over all used channels. Outputs a constant output power. Therefore, the above problem can be solved.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic block diagram of an output unit in a high frequency radio transmitter according to an embodiment of the present invention. The output section of this high-frequency wireless transmission device has a power amplifier 1 for amplifying the power of the transmission signal modulated in the transmission section, and its output terminal is connected with the duplexer 3 via the directional coupler 2. Further, an antenna 4 is connected to the transmission / reception duplexer 3. The power amplifier 1 is composed of a plurality of stages of amplification circuits such as GaAs FET (field effect transistor) that can obtain high efficiency at a low voltage, and outputs from several hundred mW to several mW by a control signal S8 given to a power control terminal. The power can be changed. The directional coupler 2 is an 8-terminal circuit (4-branch circuit) in which two transmission lines are coupled by an appropriate coupling element, and has a function of detecting the output power of the power amplifier 1. The directional coupler 2 includes a path difference type directional coupler, a series-parallel type directional coupler, a cross type directional coupler, a multi-element coupling type directional coupler, and a slot coupling type directional coupler. There is. The path difference type directional coupler includes a λ _g / 4 coupling type (where λ _g is a wavelength in a transmission line) and an anti-coupling type, and the former uses a coupling element of the same type as λ _g.
It cancels the wave that goes in the opposite direction of the sub transmission line after being separated by an odd multiple of / 4, and the latter excites the coupled wave of the opposite phase by two coupling elements that are separated by an odd multiple of λ _g / 4, and the sub transmission is performed. It cancels the waves going in the forward direction of the road. The series-parallel type directional coupler is a coupler that utilizes two transmission lines that are coupled by serially and parallelly coupled coupling elements having the same degree of coupling, and the phase relationship between the two is reversed depending on the traveling direction of radio waves. Is. The cross-shaped directional coupler is one in which two rectangular waveguides having the same long sides are made orthogonal to each other and slits of a cross shape are provided on the diagonal line of the common wall. The multi-element coupling type directional coupler is one in which a large number of loosely coupled coupling holes are provided in a common wall of two waveguides whose tube axes are parallel to each other. Further, the slot-coupling type directional coupler is one in which a slot in the tube axial direction is provided on a common wall of two waveguides.

The transmission / reception duplexer 3 sends the output power of the power amplifier 1 to the antenna 4, separates the received radio wave received by the antenna from the output power, and inputs it to the receiving section side. It is composed of a credit filter, a receiving filter, and a demultiplexing circuit. The transmission filter and the reception filter are configured by, for example, a small dielectric filter made of high-performance dielectric ceramic or the like. The transmission filter and the reception filter may be configured by other filters such as an LC filter and a surface acoustic wave filter instead of the dielectric filter. The branching circuit is composed of a strip line or the like. Since the equivalent circuit of the transmission / reception duplexer 3 is composed of the inductance L and the capacitance C, the passage loss (power attenuation amount) depends on the frequency. The transmission filter of the transmission / reception branching filter 3 is connected to the power amplifier 1 side, the reception filter is connected to the receiving section side, and the branching circuit is further connected to the antenna 4. The directional coupler 2 is connected to a detection diode 5 that detects the output power of the directional coupler 2 as a DC voltage (detection signal S5). The directional coupler 2 and the detection diode 5 constitute power detection means for detecting the output power of the power amplifier 1 and outputting the detection signal S5. The (−) side input terminal of the operational amplifier 6 is connected to the output side of the detection diode 5, and the reference signal S11 is input to the (+) side input terminal thereof.

The operational amplifier 6 is a circuit which compares the detection signal S5 given from the detection diode 5 with the reference signal S11 and changes the detection signal S5 so that the level difference between the two signals becomes zero. The output terminal is connected to the base of the PNP type control transistor 8 via the resistor 7 and the like. The emitter of the control transistor 8 is a low voltage power supply VCC
, And the collector is connected to the power control terminal of the power amplifier 1. This control transistor 8 has a function of changing the output power of the power amplifier 1 by changing the collector voltage (control signal S8) according to the magnitude of the base current given from the output terminal of the operational amplifier 6.
The operational amplifier 6, the resistor 7, the control transistor 8 and the like constitute a comparison control means. Further, the output section of this radio frequency radio transmitter is provided with a memory 9 which stores output control data for the power level to be output from the antenna output end. CPU 1 in memory 9
0 is connected, and the D / A converter 1 is further connected to the CPU 10.
1 is connected. The CPU 10 has a function of controlling reading / writing (access) of data from / to the memory 9 and outputting output control data read from the memory 9 in the form of a control signal S10. The D / A converter 11 is a CPU
It is a circuit that converts the digital control signal S10 output from 10 into an analog DC voltage (reference signal S11) and supplies the reference signal S11 to the (+) side input terminal of the operational amplifier 6. These CPU 10 and D / A converter 11
A memory access unit is constituted by the.

FIG. 2 is a diagram for explaining the output control data stored in the memory 9 in FIG. 1, and shows the frequency band (channel) used in the high frequency radio transmission apparatus with respect to the passage loss of the duplexer 3. It is a figure which shows a relationship. Between the output terminal of the power amplifier 1 and the antenna output end, a directional coupler 2 and a transmission / reception demultiplexer 3 cause a power passage loss. Generally, the passing loss of the duplexer 3 is larger than the passing loss due to the insertion loss of the directional coupler 2. Moreover, the transmission / reception duplexer 3 has the inductance L and the capacitance C.
Can be represented by an equivalent circuit of, and its pass loss (amount of power attenuation) changes depending on the frequency band used (channel used) in the high frequency wireless transmission device. For example, if the frequency band used is 82
4MH _z ~849MH _z, the use channel 0 to 800
Then, the transmission loss of the duplexer 3 is 2 dB for the channels 0 to 100 used, 1 dB for the channels 100 to 700 used, and 2 dB for the channels 700 to 800 used. However, although this passage loss varies depending on the structure of the transmission / reception duplexer 3 to be used, it is assumed here that the transmission / reception duplexer 3 having the passage loss as shown in FIG. 2 is used. In order to keep the passing loss of the duplexer 3 constant, it is necessary to add a correction value of 1 dB to 0 to 100 and 700 to 800 of the used channels. Therefore, including such a correction value,
Output control data indicating the relationship between the used channel and the output power value to be output from the antenna output terminal is stored in the memory 9 in advance.

Next, the operation of the high-frequency radio transmitter configured as above will be described. When transmitting with a certain use channel (for example, 300) using the high frequency wireless transmission device, the use channel 300 is set by a switch or the like. Then, the CPU 10 reads the output control data for the used channel 300 stored in the memory 9 in advance, and outputs the control signal S10 corresponding to the read data.
Is output. The control signal S10 is supplied to the D / A converter 11
Is converted into an analog reference signal S11 by the operational amplifier 6
Sent to the (+) side input terminal of. On the other hand, the output power of the power amplifier 1 is detected by the directional coupler 2, the detection signal S5 of the DC voltage is detected by the detection diode 5, and the detection signal S5 is sent to the (−) side input terminal of the operational amplifier 6. To be The operational amplifier 6 compares the level of the reference signal S11 with the level of the detection signal S5, and changes the output voltage according to the level difference. The output voltage of the operational amplifier 6 is sent to the base of the control transistor 8 as a base current, and the control signal S8 which is the collector voltage of the control transistor 8 is applied to the power control terminal of the power amplifier 1.
The output power of the power amplifier 1 is controlled. This allows
The output power corresponding to the reference signal S11 output from the D / A converter 11 is output from the power amplifier 1. This stable output power is transmitted / received to / from the duplexer 3 through the directional coupler 2.
Is demultiplexed and is radiated from the antenna 4 in the form of a transmission radio wave. Although the output power of the power amplifier 1 is attenuated due to the passage loss of the transmission / reception duplexer 3, the output control data stored in the memory 9 is data considering the passage loss. Corresponding output power will be output from the antenna output end.

Next, the channels used are, for example, 0 to 100.
Consider the case of sending by. The passing loss of the duplexer 3 in the used channels 0 to 100 is 2 as shown in FIG.
It is dB. In the conventional technology, since the output power of the power amplifier 1 is always input to the duplexer 3 at a constant output level, the output level corresponding to the channels 0 to 100 used is transmitted at the antenna output end. In this state, the line connection rate of the high frequency wireless transmitter is 0 to 100 channels used.
Depends on. On the other hand, in this embodiment, the correction value (1 dB) for the passage loss of the duplexer 3 is stored in the memory 9 in advance.
The output control data to which the correction value is added is read from the memory 9 by the CPU 10. The control signal S10 output from the CPU 10 is D /
Is converted into an analog reference signal S11 by the A converter 11,
Output power corresponding to the reference signal S11 is output from the antenna output end. Therefore, the output power of all used channels 0 to 800 at the antenna output end can be kept constant. Therefore, the line connection rate of the high frequency wireless transmitter is stable without depending on the channels 0 to 800 used. The present invention is not limited to the above embodiment, and various modifications can be made. Examples of modifications thereof include the following (a) to (e).

(A) In the above embodiment, the correction value corresponding to the passage loss of the duplexer 3 is stored in the memory 9 in advance. However, when the insertion loss of the directional coupler 2 is large and its passage loss cannot be ignored, a correction value corresponding to the passage loss of the directional coupler 2 is also stored in the memory 9 in advance, so that the antenna output end A constant output power can be output. (B) The power amplifier 1 is not limited to the above-mentioned embodiment, but can be composed of high frequency power amplifiers of various circuit configurations. Further, the power detection means for detecting the output power of the power amplifier 1 is composed of the directional coupler 2 and the detection diode 5, but may be composed of other circuits. (C) In the above embodiment, a correction value corresponding to the passage loss from the output terminal of the power amplifier 1 to the antenna output end is stored in the memory 9 in advance, and a constant output power is always output from the antenna output end. I am trying. However,
In the positional relationship between the high frequency radio transmitter and the base station,
In order to maintain a good communication state, it is desirable to perform control such that the output power is increased when the distance to the base station is long, and the output power is decreased when the distance to the base station is short. In such a case, data that allows the optimum output power to be output from the antenna output end according to the positional relationship with the base station may be stored in advance in the memory 9 as output control data. (D) In the above embodiment, the comparison control means is composed of the operational amplifier 6, the control transistor 8 and the like. However, the comparison control means is composed of various circuits such as a circuit structure using a comparator and other transistors. You may comprise. (E) In the above embodiment, the memory access means is configured by the CPU 10 and the D / A converter 11, but they may be configured by other memory access circuits.

[0013]

As described in detail above, according to the first aspect of the invention, the output control data including the correction value corresponding to the output power passage loss from the output side of the power amplifier to the antenna output end is stored in advance in the memory. The output control data is read by the memory access means and the output power of the power amplifier is controlled by the comparison control means. Therefore, at the antenna output end, a constant output power is always maintained over all the channels used. can get. Therefore, the line connection rate of the high frequency wireless transmitter is stable without depending on the channel used. Further, in order to maintain a good communication state, when the optimum output power is output from the antenna output terminal in correspondence with the positional relationship with the base station, the optimum output power corresponding to the positional relationship with the base station is output. The value of the output power value to be output from the antenna output terminal may be stored in advance in the memory as output control data. According to the second invention, the power detection means, the memory access means, and the comparison control means can be configured by a relatively simple circuit, and the device can be downsized.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an output unit in a high-frequency wireless transmission device showing an embodiment of the present invention.

FIG. 2 is a frequency band (channel) used by the high-frequency wireless transmission device with respect to the passing loss of the duplexer shown in FIG.
It is a figure which shows the relationship of.

[Explanation of symbols]

 1 Power Amplifier 2 Directional Coupler 3 Transmitter / Receiver Divider 4 Antenna 5 Detection Diode 6 Operational Amplifier 8 Control Transistor 9 Memory 10 CPU 11 D / A Converter S5 Detection Signal S8, S10 Control Signal S11 Reference Signal

Claims (2)

[Claims] 1. A power amplifier that amplifies and outputs power of a high frequency transmission signal at a level according to a control signal, an antenna that radiates output power in the form of a transmission radio wave and receives a reception radio wave, and the power. A transmission / reception duplexer for transmitting the output power of the amplifier to the antenna, and separating the reception radio wave received by the antenna from the output power and inputting to the receiving unit side; and the power amplifier and the transmission / reception duplexer. A power detection means connected between the power amplifier and detecting the output power of the power amplifier and outputting a detection signal; an output power passage loss from the output side of the power amplifier to the antenna output end; A memory that stores output control data that includes a correction value that indicates the relationship with the channel, and that indicates the relationship between the used channel and the output power value that should be output from the antenna output terminal, and the use channel during transmission. When a channel is set, a memory access unit that reads out the output control data corresponding to the used channel from the memory and outputs a reference signal, and compares the detection signal and the reference signal with each other to determine the level of both signals. A high-frequency wireless transmission device, comprising: a comparison control unit that gives the power amplifier the control signal for changing the detection signal so that the difference becomes zero. 2. The radio frequency radio transmitter according to claim 1, wherein the power detection means includes a directional coupler that extracts output power of the power amplifier, and a detection diode that detects an output signal of the directional coupler. Wherein the memory access means includes a central processing unit that controls reading and writing of the memory, and a digital / analog converter that converts an output digital signal of the central processing unit into the analog reference signal, The comparison control means compares the detection signal with the reference signal and changes the detection signal so that the level difference between the two signals becomes zero, and a level corresponding to the output signal of the operation amplifier. A high-frequency wireless transmission device comprising: a control transistor that outputs the control signal.