JP2006060729A - Antenna matching equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide antenna matching equipment which prevents a power amplifier circuit from being damaged and eliminates a residual matching error after the completion of matching operation. <P>SOLUTION: There are provided a variable attenuator which is inserted and connected between an input terminal of the antenna matching equipment and a matching circuit, and a changeover switch for bypassing the variable attenuator. A control circuit outputs a variable attenuator control signal for changing an attenuator value of the variable attenuator on the basis of arithmetic processing and a changeover switch control signal for changing over the changeover switch. In the variable attenuator, the attenuator value is controlled to a great attenuation amount by the variable attenuator control signal so as to absorb a great reflection power caused by impedance mismatching that occurs just after the start of the matching operation, the attenuator value is controlled to a smaller attenuation amount as the reflection power caused by the impedance mismatching is reduced with advancement of the matching operation, and the attenuator value is controlled to approximately zero attenuation amount when the matching operation is completed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an antenna matching unit that automatically matches a power source impedance at a high-frequency signal output end of a power amplifier circuit with a load impedance at an input end of an antenna (aerial).

In the prior art, a matching unit inserted and connected between a transmitter and an antenna detects a signal component (Z) indicating an impedance difference between the transmitter and the antenna and a signal component (φ) indicating a phase difference. A matching operation that makes each value zero, and a voltage standing wave ratio (VSWR) that is a ratio of traveling wave power and reflected wave power are calculated, and the best point search of VSWR is performed, so that this becomes the best value. The matching accuracy is improved by performing this matching operation and repeating this matching operation. (For example, refer to Patent Document 1).
JP-A-9-162757 (page 3, FIG. 1)

FIG. 3 shows an example of a block diagram of the prior art antenna matching device.
In FIG. 3, 1 is a power amplifier circuit, 11 is an antenna, 2 is an antenna matching unit inserted and connected between the power amplifier 1 and the antenna 11, 4 is a matching circuit, 5 is a variable capacitor, 6 is a variable inductor, Reference numeral 7 is a Pf (traveling wave power) and Pr (reflected wave power) detection circuit, 8 is an R (impedance resistance) and Φ (impedance reactance) detection circuit, and 12 is a block of a control circuit.
The antenna matching unit 2 receives the detection signals of the matching circuit 4, the Pf / Pr detection circuit 7, the R / Φ detection circuit 8, the Pf / Pr detection circuit 7 and the R / Φ detection circuit 8 as inputs. Each of the detected signals is subjected to a matching operation calculation process, and the matching circuit 4 automatically performs impedance matching between the power amplifier circuit 1 and the antenna 11, and the control circuit 12 outputs matching control signals 20a and 20b. It is equipped with.
The matching operation in FIG. 3 will be described.
Prior to the start of the matching operation, the control circuit 12 sets the matching control signals 20a and 20b to the variable capacitor 5 and the variable capacitor 5 so that the respective variable positions of the variable capacitor 5 and the variable inductor 6 are set to the homing positions, which are predetermined start positions. Output to the inductor 6.
In the example of the matching circuit 4, the reactance of the variable capacitor 5 and the variable inductor 6 is controlled to a position where the minimum value is obtained.
A circuit formed by the matching circuit 4 and the antenna 11 connected in series with the matching circuit 4 serves as a load circuit for the output of the power amplifier circuit 1.
Next, high-frequency signal power (RF power) output from the power amplifier circuit 1 is input to the matching circuit 4. At the same time, the minute RF power is coupled to the signal circuit A 0 point and inputted to the R and Φ detection circuit 8. The R / Φ detection circuit 8 detects an R / Φ detection signal obtained as an error signal from the difference between the output impedance value of the power amplifier circuit 1 and the input impedance value of the antenna matching unit 2. The R and Φ detection signals are respectively compared with the R component and Φ component when the output impedance (reference impedance; for example, 50Ω) of the power amplifier circuit 1 is used. At this time, since the impedance of the signal circuit A0 point (impedance seen from the input terminal to the matching circuit 4 and the antenna 11 side) is not matched with the output impedance of the power amplifier circuit 1, the difference (error) of the R component or the Φ component A difference (error) is generated, and an error voltage corresponding to the error is generated as an R or Φ detection output.
The control circuit 12 takes in the R and Φ detection outputs output from the R and Φ detection circuit 8, and the capacitance value of the variable capacitor 5 so that the error from the reference impedance, which is the operation processing of the matching operation, approaches zero or zero as much as possible. The matching control signals 20a and 20b are output as drive signals for changing the inductance value of the variable inductor 6.
If the impedance of the signal circuit A0 point is the same as the reference impedance, the R and Φ detection circuit 8 is preliminarily adjusted so that the R and Φ detection outputs are each error voltage 0 V, assuming that no error has occurred. .
At this time, the minute RF power is coupled to the signal circuit A 0 point and is also input to the Pf and Pr detection circuit 7. The Pf and Pr detection circuit 7 detects Pf and Pr detection signals of Pf (traveling wave power component) and Pr (reflected wave power component). The Pf and Pr detection signals are supplied to the control circuit 12 as Pf and Pr values that are voltage values. The control circuit 12 calculates a ratio between the Pf value and the Pr value to obtain a standing wave ratio. The obtained standing wave ratio is compared with a prescribed value stored in the control circuit 12 in advance, and it is confirmed that it is equal to or less than the prescribed value.
With the above matching operation, when the standing wave ratio is not more than the specified value and the R and Φ detection outputs of the R and Φ detection circuit 8 come close to 0V and 0V, respectively, the impedance of the signal circuit A0 point Corresponds to the output impedance (reference impedance) of the power amplifying circuit 1 or infinitely, and the impedance matching between the power amplifying circuit 1 and the antenna 11 is achieved. At this time, the high frequency signal power (RF power) output from the power amplifier circuit 1 is supplied to the antenna 11 most efficiently.
The load impedance of the power amplifier circuit 1 immediately after the start of the matching operation is considerably lower than the reference impedance (eg, the reference impedance is 50Ω) because the reactances of the variable capacitor 5 and the variable inductor 6 are minimum values. In this case, the impedance of the matching circuit 4 including the variable capacitor 5 and the variable inductor 6 is about several Ω to several tens of Ω).
Since the load impedance of the power amplifier circuit 1 is lower than the reference impedance, the output is overloaded. This overload condition is reduced as the alignment operation proceeds. When the matching operation is completed, the output impedance of the power amplifier circuit 1 is almost the same as the load impedance, and the matching is achieved.
From the start of the matching operation to the middle stage of the matching operation, the output of the power amplifying circuit 1 is in an overload state. Therefore, an overcurrent flows through the semiconductor output amplifying element included in the power amplifying circuit 1 in the overloaded state. In rare cases, the internal circuit of the semiconductor may be damaged by overcurrent. This problem tends to occur more easily as the output amplifier element of a semiconductor for high power is used.

FIG. 4 shows another example of a block diagram of a conventional antenna matching device in which the above-mentioned drawbacks of the prior art are addressed.
In FIG. 4, 10a and 10b are change-over switches inserted and connected between the power amplifier circuit 1 and the matching circuit 4, and 14 is connected between the power amplifier circuit 1 and the matching circuit 4 by switching the connection of the change-over switches 10a and 10b. It is a fixed attenuator having a reference impedance to be inserted and connected, and the control circuit 12 outputs a signal for switching and controlling the changeover switches 10a and 10b. The other blocks have the same configuration as that shown in FIG.
In the fixed attenuator 14, the contacts of the changeover switches 10 a and 10 b are inserted and connected between the power amplifier circuit 1 and the matching circuit 4 in accordance with the changeover switch control signal from the control circuit 12 during the matching operation. On the other hand, when the matching operation is completed, the contacts of the changeover switches 10a and 10b are directly connected between the power amplifier circuit 1 and the matching circuit 4 according to the changeover switch control signal from the control circuit 12, and the fixed attenuator 14 is removed. .
When the fixed attenuator 14 is connected, it works to reduce the reflected wave power, so the next problem that occurred in the configuration of FIG. 3 is “From the start of the matching operation to the middle of the matching operation. Since the output of the power amplifier circuit 1 is in an overload state, an overcurrent is caused to flow through the semiconductor output amplifier element included in the power amplifier circuit 1 in the overload state. The problem is that the more the semiconductor power amplifying element for high power is, the more likely this problem is to occur. That is, the output of the power amplifying circuit 1 is overloaded. Can be reduced.
As a result, it is possible to prevent an overcurrent from flowing through the semiconductor output amplifying element included in the power amplifying circuit 1, and to prevent damage to the internal circuit of the semiconductor.

The fixed attenuator 14 in FIG. 4 is connected during the alignment operation, and the alignment is completed and is removed when the device is in use. This is to prevent a reduction in power efficiency of the entire device due to power loss due to the fixed attenuator in the use state of the device. Therefore, the amount of attenuation of the fixed attenuator 14 is determined so that the output semiconductor circuit of the power amplifying circuit 1 is protected from damage at the maximum value of the reflected power due to impedance mismatch at a predetermined output of the power amplifying circuit 1. .
For this reason, the matching circuit 4 during the matching operation is in a matching state with reduced signal power, and the matching positions of the variable capacitor 5 and the variable inductor 6 included in the matching circuit 4 at this time and the matching operation are completed. When a predetermined signal power is supplied to the matching circuit 4, an error occurs in each matching position of the variable capacitor 5 and the variable inductor 6.
When the fixed attenuator 14 is removed and the power amplifying circuit 1 and the matching circuit 4 are directly connected, a matching error remains, and the output impedance of the power amplifying circuit 1 and the antenna 11 in the use state of the device are included in the load. A slight error occurs in the matching state with the impedance of the matching circuit 4, and the optimum matching state is not achieved. Therefore, the maximum efficiency of the radiation power of the antenna 11 cannot be obtained.

  Fixed in the matching operation of the matching circuit for matching the output impedance of the power amplifier circuit and the input impedance of the antenna after preventing the amplification element from being damaged due to the overload state at the output end of the power amplifier circuit as described above The problem is to eliminate the residual matching error when the attenuator is inserted and to prevent the matching accuracy from being lowered.

  An object of the present invention is to provide an antenna matching unit that solves the above-described problems, prevents damage to a power amplifier circuit, and eliminates a residual matching error after completion of a matching operation.

In order to achieve this object, the antenna matching unit is inserted and connected between a power amplifier circuit as a signal source and the antenna, and includes a matching circuit, a Pf / Pr detection circuit, an R / Φ detection circuit, and the Pf , Pr detection circuit and each detection signal output from the R, Φ detection circuit are input, and a calculation operation of matching operation is performed by each of the input detection signals, and the matching circuit is connected to the power amplification circuit and the antenna. An antenna matching device including a control circuit that outputs a matching control signal for automatically performing impedance matching between
A variable attenuator inserted and connected between the input terminal of the antenna matching unit and the matching circuit; and a changeover switch for bypassing the variable attenuator.
The control circuit outputs a variable attenuator control signal for changing the attenuator value of the variable attenuator based on the arithmetic processing and a changeover switch control signal for changing over the changeover switch.
The variable attenuator is controlled by the variable attenuator control signal so that a large amount of reflected power due to impedance mismatch generated immediately after the start of the matching operation is absorbed, and the attenuation value is increased as the matching operation proceeds. As the reflected power due to impedance mismatch is reduced, the attenuator value is controlled to a small attenuation amount, and when the matching operation is completed, the attenuator value is controlled to an attenuation amount of substantially zero,
The changeover switch is configured to be controlled to bypass the variable attenuator by a changeover switch control signal after the attenuation amount is controlled to be substantially zero.

  When the present invention is implemented, the matching accuracy of the conventional antenna matching device is lowered, whereas the antenna matching device of the present invention ensures an optimum matching state. In this way, the power amplifying circuit which is the signal source of the matching circuit is protected from an overload state that appears during the matching operation from the damage of the internal amplifying element of the power amplifying circuit and is used for protecting the power amplifying circuit. As a result, it is possible to improve the matching accuracy by eliminating the residual matching error due to the above-mentioned characteristics. Therefore, the service life of the power amplifier circuit is improved, and not only the reliability of the device but also the communication quality is improved. It is clear that it is effective.

A block diagram of the antenna matching device of the present invention is shown in FIG. In FIG. 1, reference numeral 1 denotes a power amplifier circuit, 11 denotes an antenna, and 2 denotes an antenna matching unit inserted and connected between the power amplifier circuit 1 and the antenna 11.
The antenna matching unit 2 includes a matching circuit 4 including a variable capacitor 5 and a variable inductor 6, a Pf (traveling wave power) and Pr (reflected wave power) detection circuit 7, R (resistance component of impedance), and Φ (impedance of impedance). Reactance) The detection circuit 8 and the changeover switches 10a and 10b have the same configuration as that in FIG. 4, and 3 is inserted and connected between the power amplifier circuit 1 and the matching circuit 4 by switching the connection of the changeover switches 10a and 10b. 9 is a matching control signal 20a for controlling the variable capacitor 5 provided in the matching circuit 4 with the detection outputs of the Pf, Pr detection circuit 7 and R, and Φ detection circuit 8 as inputs. A matching control signal 20b for controlling the variable inductor 6, a changeover switch control signal 21 for controlling the changeover switches 10a and 10b, and a variable attenuator are controlled. The control circuit 9 is configured to output a variable attenuator control signal 22 to be controlled. A variable attenuator control signal 22 for controlling the variable attenuator 3 is provided from the control circuit 9 in place of the fixed attenuator as compared with FIG. It is different in that it is output.

Next, an example of the matching operation will be described. The matching operation is performed by the control operation of the control circuit 9. In the following, description will be made in the order of STEP of the alignment operation flowchart shown in FIG.
(STEP 1) Prior to the start of the matching operation, the matching control signals 20a and 20b are sent from the control circuit 9 so that the variable positions of the variable capacitor 5 and the variable inductor 6 of the matching circuit 4 are set to the homing positions, which are predetermined start positions. Is output to the variable capacitor 5 and the variable inductor 6. In the setting example of the homing position that is the starting position of the matching circuit 4, the reactance of each of the variable capacitor 5 and the variable inductor 6 is controlled to a minimum value.
The respective contacts of the changeover switches 10a and 10b are controlled by the changeover switch control signal 21 output from the control circuit 9 so that the variable attenuator 3 is inserted between the signal circuit points A and B prior to the start of the matching operation. .
The variable attenuator 3 is controlled by the variable attenuator control signal 22 output from the control circuit 9 so that the attenuator value prior to the start of the matching operation becomes an arbitrarily large amount of attenuation.
(STEP 2) The high frequency signal power (RF power) output from the power amplifier circuit 1 is input to the matching circuit 4 via the circuit of the changeover switch 10a, the variable attenuator 3, and the changeover switch 10b in series.
At the same time, the minute RF power is coupled to the signal circuit B point having the impedance of the signal circuit B point, and is input to the R and Φ detection circuit 8.
The load impedance of the power amplifier circuit 1 immediately after the start of the matching operation is considerably lower than the reference impedance (eg, the reference impedance is 50Ω) because the reactances of the variable capacitor 5 and the variable inductor 6 are minimum values. In this case, the impedance of the matching circuit 4 including the variable capacitor 5 and the variable inductor 6 is about several Ω to several tens of Ω).
(STEP 3) The R and Φ detection signals detected by the R and Φ detection circuit 8 are input to the control circuit 9.
R input to the control circuit 9, RB that is the R component of the Φ detection signal, and ΦB that is the Φ component are output impedance (reference impedance; for example, 50Ω) of the power amplifier circuit 1 stored in the memory in the control circuit 9. R0 as the R component and Φ0 as the Φ component.
(STEP 4) Since the matching operation is started and the impedance at the signal circuit B point (impedance seen from the antenna 11 side) is not matched with the output impedance of the power amplifier circuit 1 (signal circuit A point), the difference between the R components ( Error) or a difference between Φ components (error) occurs, and an error voltage corresponding to the error is generated as an R or Φ detection output. That is, the error voltages [VR; (the difference between RB and R0 is the voltage conversion value) and VΦ; (the difference between ΦB and Φ0 is the voltage conversion value)], which are the detection outputs of the R and Φ detection circuits 8, are the progress of the matching operation. Accordingly, the error is reduced, that is, the error is changed in the decreasing direction, and the control is performed in the direction in which the matching can be achieved. Since the load impedance of the power amplifier circuit 1 is lower than the reference impedance, the output is overloaded. This overload condition is reduced as the alignment operation proceeds.
(STEP 5) In the variable attenuator 3, the R and Φ detection circuit 8 detects the R and Φ detection signals obtained as error signals from the difference between the output impedance value of the power amplifier circuit 1 and the input impedance value of the antenna matching unit 2. The control circuit 9 performs arithmetic processing based on the value, and takes a large attenuation so as to absorb the large reflected power due to the impedance mismatch occurring immediately after the start of the matching operation, and the reflected power decreases as the matching operation proceeds. Therefore, the variable attenuator control signal output from the control circuit 9 is sequentially controlled so as to take a small attenuation.
Since the attenuation amount of the variable attenuator 3 is controlled using the error voltage that is the detection output of the R and Φ detection circuit 8, it is controlled in proportion to the error voltage, and the error voltage is large at the start of matching. The attenuation amount also takes a large value to absorb the maximum reflected power, and as the matching operation proceeds, the error voltage becomes small and the attenuation amount becomes a small value so that the signal circuit B point approaches the matching state with a predetermined signal power. Sequentially controlled.
(STEP 6) The alignment operation is completed when the control proceeds so that the error becomes zero. When the matching operation is completed, the signal circuit A point and the signal circuit B point are directly connected by the changeover switches 10a and 10b, and the variable attenuator 3 is controlled to be bypassed and removed.
After the matching operation is completed, the circuit formed by the matching circuit 4 and the antenna 11 connected in series to the matching circuit 4 becomes a load circuit in use of the system for the output of the power amplifier circuit 1.
When the matching operation is completed, there is no residual matching error, and the output impedance of the power amplifier circuit 1 is almost the same as the load impedance, so that an optimum matching state is achieved and a message can be transmitted.

The control circuit 9 takes in the R and Φ detection outputs output from the R and Φ detection circuit 8, and the capacitance value of the variable capacitor 5 and the variable inductor so that the error from the reference impedance, which is the calculation process of the matching operation, becomes substantially zero. Matching control signals 20a and 20b are output as drive signals for changing the inductance value of 6.
Note that if the impedance of the signal circuit is the same as the reference impedance, the R and Φ detection circuit 8 assumes that no error has occurred, and the control conditions of the control circuit 9 are set in advance so that the R and Φ detection outputs are each error voltage 0V. It is said.
Further, the minute RF power is coupled to the signal circuit B point and is also input to the Pf and Pr detection circuit 7. The Pf and Pr detection circuit 7 detects Pf and Pr detection signals of Pf (traveling wave power component) and Pr (reflected wave power component). The Pf and Pr detection signals are supplied to the control circuit 9 as voltage values Pf and Pr. The control circuit 9 calculates the ratio between the Pf value and the Pr value, obtains the standing wave ratio, and stores it in the control circuit 9 in the memory. The standing wave ratio stored in the memory is compared with a specified value stored in the memory in the control circuit 9 in advance and is equal to or less than the specified value.

With the above matching operation, when the R and Φ detection outputs of the R and Φ detection circuits 8 become approximately 0 V, if the standing wave ratio is less than the specified value, the predetermined signals at the signal circuits A and B This is when the power impedance substantially matches the output impedance (reference impedance) of the power amplifier circuit 1, and the power amplifier circuit 1 and the antenna 11 are in impedance matching. At this time, the high frequency signal power (RF power) output from the power amplifier circuit 1 is supplied to the antenna 11 most efficiently. Furthermore, the most efficient radiation is made from the antenna 11.
As a result, it is possible to prevent an overcurrent from flowing through the semiconductor output amplifying element included in the power amplifying circuit 1, and to prevent damage to the internal circuit of the semiconductor.

  INDUSTRIAL APPLICABILITY The present invention is applied to a radio communication system used for short-wave mobile communication or fixed communication in which antenna impedance changes greatly depending on the radio frequency, antenna shape, and antenna installation environment, and can be used for a communication business or the like. .

It is a block diagram of the antenna matching device which concerns on this invention. It is a matching operation | movement flowchart figure of the antenna matching device which concerns on this invention. It is a block diagram of the antenna matching device concerning a prior art. (Conventional example 1) It is a block diagram of the antenna matching device concerning a prior art. (Conventional example 2)

Explanation of symbols

1 Power amplification circuit 2 Antenna matching device 3 Variable attenuator
4 Matching circuit 5 Variable capacitor
6 variable inductor 7 Pf, Pr detection circuit 8 R, Φ detection circuit 9, 12 control circuit 10a, 10b changeover switch
11 antenna 13 fixed attenuator 20a, 20b matching control signal 21 changeover switch control signal 22 variable attenuator control signal S1 to S6 STEP1 to STEP6

Claims (1)

It is inserted and connected between the power amplifier circuit which is a signal source and the antenna, and the matching circuit, the Pf / Pr detection circuit, the R / Φ detection circuit, the Pf / Pr detection circuit and the R / Φ detection circuit are output. Matching control in which each detection signal to be input is input, and a matching operation is calculated by each input detection signal, and the matching circuit automatically performs impedance matching between the power amplifier circuit and the antenna An antenna matching device including a control circuit for outputting a signal,
A variable attenuator inserted and connected between the input terminal of the antenna matching unit and the matching circuit; and a changeover switch for bypassing the variable attenuator.
The control circuit outputs a variable attenuator control signal for changing the attenuator value of the variable attenuator based on the arithmetic processing and a changeover switch control signal for changing over the changeover switch.
The variable attenuator is controlled by the variable attenuator control signal so that a large amount of reflected power due to impedance mismatch generated immediately after the start of the matching operation is absorbed, and the attenuation value is increased as the matching operation proceeds. As the reflected power due to impedance mismatch is reduced, the attenuator value is controlled to a small attenuation amount, and when the matching operation is completed, the attenuator value is controlled to an attenuation amount of substantially zero,
The antenna matching device, wherein the changeover switch is configured to be controlled to bypass the variable attenuator by a changeover switch control signal after the attenuation is controlled to be substantially zero.

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