JP2007116339A - Impedance matching unit and wireless communication apparatus employing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mobile wireless apparatus capable of suppressing a mismatching loss lower under any circumstance by adaptively controlling the impedance between antennas and a wireless transmission circuit. <P>SOLUTION: In the impedance matching unit for carrying out impedance matching between the antennas 101, 108 and the wireless transmission circuit 107, a variable distributor 105 distributes a wireless signal from the wireless transmission circuit 107 into two; first and second wireless signals. A variable matching circuit 109 executes impedance conversion processing for the first or second wireless signal at a prescribed impedance conversion ratio and outputs the result to the antennas 101, 108, from which radio waves are emitted. When the antennas 101, 108 emits the wireless signals from the wireless transmission circuit 107, a signal strength detector 106 detects a level of a reflection wave signal reflected in the variable distributor 105, and a control section 111 changes the impedance conversion ratio of the variable matching circuit 109 to substantially minimize the level of the reflection wave signal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an impedance matching device that performs impedance matching so that the impedance of a wireless antenna matches the impedance of a wireless communication circuit, and a wireless communication device using the impedance matching device.

  In recent years, mobile communication systems using wireless communication devices such as mobile phones have been rapidly developed. In the wireless communication device, in order to perform wireless communication efficiently, it is necessary to match the impedance of the antenna so as to match the impedance of the wireless communication device. However, the mobile phone is used in the vicinity of the human body, and even if impedance matching is performed in free space, if the human body is close to the antenna, the impedance mismatching state occurs, transmission power is lost, and wireless communication cannot be performed. It may be in a state.

  Therefore, for example, Patent Document 1 proposes an automatic antenna matching circuit for impedance matching between a radio and an antenna. In the automatic antenna matching circuit, an impedance matching circuit that adjusts impedance by a varicap diode is provided between the radio and the antenna, and the power detection circuit 2 represents the power of signals at the front and rear stages of the impedance matching circuit. Generate two voltage signals. The comparator compares the two voltage signals. Based on the comparison result, the applied voltage control circuit generates a voltage signal for controlling the capacitance of the varicap diode so as to reduce the difference between the two voltage signals, and supplies the voltage signal to the varicap diode.

  In addition, as another method of changing the impedance of the antenna, the element value of the load impedance of the parasitic antenna is controlled so that the value of the current flowing through the housing during transmission of the wireless communication device is less than a predetermined value and the specific absorption A method of controlling the rate (SAR (Specific Absorption rate)) to be a predetermined value or less is disclosed (for example, see Patent Document 2).

Japanese Patent Application Laid-Open No. 11-251928. JP 2004-336742 A.

  However, in the antenna automatic matching circuit disclosed in Patent Document 1, since the varicap diode that is a variable impedance element is connected to the feeding antenna, the varicap diode may be destroyed during transmission. Further, in the wireless antenna device disclosed in Patent Document 2 and the wireless communication device using the wireless antenna device, since the feeding antenna and the parasitic antenna are independent, the load impedance of the parasitic antenna gives the impedance of the feeding antenna. The impact is small. Therefore, the effect of correcting the impedance deviated from the impedance matching state is small.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems and adaptively control the impedance so that the impedance matching device capable of keeping the impedance mismatch loss low in any situation of the mobile terminal, and the same It is to provide a wireless communication apparatus using the.

An impedance matching device according to a first invention is an impedance matching device that performs impedance matching between a plurality of antennas including a first antenna and a second antenna and a wireless communication device,
The radio signal from the radio communication device is distributed to a plurality of radio signals at a predetermined distribution ratio different from 1, and a first radio signal is output from the distributed radio signals, while the distributed radio Distribution means for outputting a second radio signal different from the first radio signal among the signals;
Variable matching means for executing impedance conversion processing with a predetermined impedance conversion ratio on the first or second radio signal output from the distributing means, and outputting and radiating to the first or second antenna;
Signal detection means for detecting a level of a reflected wave signal reflected to the distribution means when a radio signal from the wireless communication device is radiated from the first and second antennas;
Control means for changing the impedance conversion ratio of the variable matching means based on the level of the reflected wave signal detected by the signal detection means so that the level of the reflected wave signal is substantially minimized. It is characterized by that.

In the impedance matching device, when the distribution ratio is set so that the level of the first wireless signal is higher than the level of the second wireless signal, the first wireless signal from the distributing means is Output and radiate to the first antenna via the first impedance matching circuit, while output and radiate the second radio signal from the distributing means to the second antenna via the variable matching means A first state to
When the distribution ratio is set so that the level of the first radio signal is lower than the level of the second radio signal, the second radio signal from the distribution means is converted into a second impedance matching circuit. A second state in which the first radio signal from the distributing means is output and radiated to the first antenna via the variable matching means; It further comprises switching means for selectively switching between.

In the impedance matching apparatus, the distribution unit includes a radio signal received by the first antenna, and a radio signal received by the second antenna and then input through the variable matching unit. And output to the wireless communication device,
The signal detection means detects the level of the synthesized radio signal output from the distribution means,
The control means, based on the level of the synthesized radio signal detected by the signal detection means, has an impedance conversion ratio of the variable matching means so that the level of the synthesized radio signal is substantially maximized. It is characterized by changing.

  Further, in the impedance matching apparatus, the signal detection means includes an integration circuit, and outputs a level obtained by temporally integrating the level of the detected signal by the integration circuit to the control means.

A wireless communication system according to a second aspect of the present invention includes the impedance matching device,
And a radio communication device that receives and receives a radio signal received from the impedance matching device, while generating a radio signal to be transmitted and outputting the radio signal to the impedance matching device.

  Therefore, according to the impedance matching device and the radio communication terminal device using the same according to the present invention, the impedance can always be adaptively controlled in various environments where the antenna is placed, so that the loss due to the impedance mismatch loss is reduced. Therefore, it is possible to stably perform wireless communication with good communication quality. Also, by controlling the variable matching means connected to the auxiliary antenna mounted separately from the feeding antenna (specifically, controlling the reverse bias voltage to the variable capacitance diode to control the impedance conversion ratio) Therefore, it is possible to prevent a large amount of power from being applied to the variable matching means, thereby preventing the element from being damaged and stably controlling impedance matching.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In addition, in each following embodiment, the same code | symbol is attached | subjected about the same component.

First embodiment.
FIG. 1 is a block diagram showing a configuration of a portable wireless device equipped with an impedance matching device according to a first embodiment of the present invention. In FIG. 1, an antenna 101 is used as a communication antenna for a mobile phone, and an antenna 108 is used as a communication antenna for Bluetooth.

  First, a case where communication is performed using a mobile phone will be described. When information indicating that the mobile phone communication is performed or the Bluetooth communication is terminated is input from the input operation unit 112, the input operation unit 112 transmits the information to the control unit 111. Based on the information, the control unit 111 switches the switch circuits 102 and 104 as follows. Here, the switch circuit 102 includes three switches 120a, 102b, and 102c, and the switch circuit 104 includes three switches 104a, 104b, and 140c. The control unit 111 switches the switches 102a, 102b, and 102c to the contacts a, b, and b, respectively, and switches the switches 104a, 104b, and 104c to the contacts a, b, and b, respectively. A termination resistor 102R1 is connected to the contact b of the switch 102a, and a termination resistor 102R2 is connected to the contact b of the switch 102c. A termination resistor 104R1 is connected to the contact b of the switch 104a, and a termination resistor 104R2 is connected to the contact b of the switch 104c.

  The cellular phone radio signal generated by the radio transmission circuit 107 is input to the variable distributor 105 via the signal strength detector 106 and the circulator 120. The variable distributor 105 distributes the input radio signal at a predetermined power distribution ratio (for example, 20: 1) set by the control unit 111, and the radio signal having larger power is the switch 104 a and the matching circuit 103. The wireless signal having a smaller power is output and radiated to the antenna 108 via the switch 104c, the matching circuit 110, and the switch 102c. Here, the matching circuit 103 matches the impedance viewed from the matching circuit 103 on the antenna 101 side with the impedance of the matching circuit 103 on the antenna 101 side, and the impedance viewed from the matching circuit 103 on the variable distributor 105 side of the matching circuit 103. This is an impedance conversion circuit having a fixed impedance conversion ratio for matching with the impedance of the variable distributor 105 side. The matching circuit 110 matches the impedance of the matching circuit 110 viewed from the antenna 108 side with the impedance of the matching circuit 110 on the antenna 108 side, and the impedance of the matching circuit 110 viewed from the variable distributor 105 side is variable. This is an impedance conversion circuit having a fixed impedance conversion ratio for matching with the impedance of the distributor 105 side. Further, the configurations of the variable matching circuit 109 and the signal strength detection unit 106 will be described in detail with reference to FIGS.

  A combined signal of the reflected signal from the antenna 101 and the antenna 108, the incident signal from the antenna 101 to the antenna 108, and the incident signal from the antenna 108 to the antenna 101 (that is, the signal strength from the variable distributor 105 via the circulator 120) The signal intensity of the reflected signal that is reflected (returned) to the detector 106 is detected by the signal intensity detector 106, and the detected signal intensity is transmitted to the controller 111. The control unit 111 performs control so as to change the reverse bias voltage applied to the variable capacitance diodes D1 and D2 (FIG. 2) of the variable matching circuit 109 so that the detected signal intensity is substantially minimized. The control unit 111 also controls the distribution ratio of the variable distributor 105 as will be described in detail later. At the time of reception, the radio signal for mobile phone received by the antennas 101 and 108 is input to the radio reception circuit 114 via the signal strength detector 113 via the circulator 120 and then demodulated. Here, the control unit 111 Is a reverse bias applied to the variable capacitance diodes D1 and D2 (FIG. 2) of the variable matching circuit 109 so that the signal strength of the received radio signal input from the circulator 120 to the signal strength detector 113 is substantially maximized. Control to change the voltage.

  Next, a case where communication is performed using Bluetooth will be described. When information indicating that Bluetooth communication or mobile phone communication is terminated is input from the input operation unit 112, the input operation unit 112 transmits the information to the control unit 111. Based on the information, the control unit 111 switches the switch circuits 102 and 104 as follows. The control unit 111 switches the switches 102a, 102b, and 102c to the contacts b, a, and a, respectively, and switches the switches 104a, 104b, and 104c to the contacts b, a, and a, respectively.

  The wireless signal for Bluetooth generated by the wireless transmission circuit 107 is input to the variable distributor 105 via the signal strength detection unit 106 and the circulator 120. The variable distributor 105 distributes the input radio signal at a predetermined power distribution ratio (for example, 1:20) set by the control unit 111, and the radio signal having a larger power is the switch 104b and the matching circuit 110. The radio signal having a smaller power is output to the antenna 101 via the switch 104a, the matching circuit 103, and the switch 102a, and then radiated.

  A combined signal of the reflected signal from the antenna 108 and the antenna 101, the incident signal from the antenna 108 to the antenna 101, and the incident signal from the antenna 101 to the antenna 108 (that is, the signal strength from the variable distributor 105 via the circulator 120 The signal intensity of the reflected signal that is reflected (returned) to the detector 106 is detected by the signal intensity detector 106, and the detected signal intensity is transmitted to the controller 111. The control unit 111 performs control so as to change the reverse bias voltage applied to the variable capacitance diodes D1 and D2 (FIG. 2) of the variable matching circuit 109 so that the detected signal intensity is substantially minimized. The control unit 111 also controls the distribution ratio of the variable distributor 105 as will be described in detail later. At the time of reception, the radio signal for mobile phone received by the antennas 101 and 108 is input to the radio reception circuit 114 via the signal strength detector 113 via the circulator 120 and then demodulated. Here, the control unit 111 Is a reverse bias applied to the variable capacitance diodes D1 and D2 (FIG. 2) of the variable matching circuit 109 so that the signal strength of the received radio signal input from the circulator 120 to the signal strength detector 113 is substantially maximized. Control to change the voltage.

  FIG. 2 is a circuit diagram showing a configuration of the variable matching circuit 109 of FIG. In FIG. 2, the common terminal of the switch 104b of the switch circuit 104 is connected to the switch 102b of the switch circuit 102 via the variable capacitance diode D1 that is a series load element, and via the variable capacitance diode D2 that is a parallel load element. Grounded. The bias voltage generator 121 generates a predetermined bias voltage based on a control signal from the control unit 111 and applies it to both ends of the variable capacitance diode D1 via the high frequency blocking inductors L11 and L12. The bias voltage generator 122 generates a predetermined bias voltage based on the control signal from the control unit 111 and applies it to both ends of the variable capacitance diode D2 via the high frequency blocking inductors L21 and L22. Here, each capacitance value can be changed by changing the bias voltage applied to each of the variable capacitance diodes D1, D2, and the impedance conversion ratio of the variable matching circuit 109 can be changed.

  FIG. 3 is a circuit diagram of a variable matching circuit 109A which is a modification of the variable matching circuit 109 of FIG. In the first embodiment, a variable matching circuit 109A may be used instead of the variable matching circuit 109. Compared with the variable matching circuit 109, the variable matching circuit 109A has a series load element Z1 inserted between the switch 104b and the variable capacitance diode D1, and a parallel load element Z2 inserted between the switch 104b and the variable capacitance diode D2. It is characterized by being inserted.

  In the initial state of the variable matching circuit 109, when communication is performed with a mobile phone, the antenna 101 is subjected to Bluetooth communication with bias voltages Vb1 and Vb2 that can be impedance matched in free space. Reference numeral 108 denotes a state in which bias voltages Vb1 and Vb2 that allow impedance matching in a free space are applied. For example, when communication is performed using a mobile phone, the bias voltage Vb1 is 3V and the bias voltage Vb2 is 3.5V. When communication is performed using Bluetooth, the bias voltage Vb1 is 4V and the bias voltage Vb2 is 4.5V.

  FIG. 4 is a block diagram showing a configuration of the signal strength detection unit 106 of FIG. In FIG. 4, the radio signal from the radio transmission circuit 107 is output to the variable distributor 105 via the directional coupler 131. When the reflected signal or the radio signal from the variable distributor 105 is input to the directional coupler 131, the radio signal having a part of the power is separated by the directional coupler 131 and output to the signal intensity detector 132. The intensity is detected by the signal intensity detector 132 and output to the control unit 111.

  A method for adaptively matching the impedance of the antenna 101 and the antenna 108 in various environments in the portable radio apparatus configured as described above will be described. Assume that the antenna 101 is impedance matched in free space. The bias voltages Vb1 and Vb2 at this time are set to 3 V and 3.5 V, for example. A radio signal generated by the radio transmission circuit 107 is input to the antenna 101 through the directional coupler 131, the variable distributor 105, and the matching circuit 103 of the signal strength detection unit 106 and is radiated from the antenna 101. The radio signal generated by the radio transmission circuit 107 is also radiated from the antenna 108 via the variable distributor 105 and the variable matching circuit 109. At this time, the radio signal radiated from the antenna 101 and the radio signal radiated from the antenna 108 are radio signals distributed by the variable distributor 105 at a distribution ratio of 20: 1.

  The signal strength detector 132 of the signal strength detector 106 detects the voltage of the detected radio signal (hereinafter referred to as a reflected voltage), and outputs the detected reflected voltage to the controller 111. The voltage value at this time is an initial voltage Vt0. In the present embodiment, the initial voltage Vt0 is defined as a reflected voltage value that the antenna 101 or 108 considers to be in free space. For example, even if the antenna 101 or 108 is in free space, the reflected voltage varies slightly depending on the surrounding environment, but when the initial voltage Vt0 does not exceed 1V, the initial voltage Vt0 is set to 1V. The initial voltage Vt0 is an average value of several values acquired by the signal strength detection unit 106.

  When the antenna 101 is close to the human body, impedance mismatch of the antenna 101 occurs, a reflected signal from the antenna 101 is generated, and the signal returns to the directional coupler 131. In addition, the reflected signal from the antenna 108, the incident signal radiated from the antenna 101 and incident on the antenna 108, and the signal radiated from the antenna 108 and incident on the antenna 101 return to the directional coupler 131. At this time, the reflected signal from the antenna 101 and the incident signal radiated from the antenna 108 and incident on the antenna 101 and the reflected signal from the antenna 108 and the incident signal radiated from the antenna 101 and incident on the antenna 108 are respectively received by the variable distributor 105. Synthesized at a synthesis ratio of 20: 1.

  A combined signal in which the reflected signal from the antenna 101 and the incident signal radiated from the antenna 108 and incident on the antenna 101 are combined with the reflected signal from the antenna 108 and the incident signal radiated from the antenna 101 and incident on the antenna 108 at a distribution ratio of 20: 1. The signal is a reflected signal from the antenna 101 and an incident signal that is radiated from the antenna 108 and incident on the antenna 101 and 1/21 is a reflected signal from the antenna 108 and the antenna. The incident signal radiated from 101 and incident on the antenna 108 is included. When the reflected voltage Vt1 becomes larger than Vt0, the control unit 111 starts controlling the bias voltages Vb1 and Vb2 so that the reflected voltage becomes smaller. This state is referred to as a human body proximity state 1. The control processing of the bias voltages Vb1 and Vb2 will be described in detail with reference to FIGS.

  Next, it is assumed that Bluetooth communication is selected by the input operation unit 112 such as a button for notifying the start of Bluetooth communication. The input operation unit 112 transmits the information to the control unit 111, and the control unit 111 switches the switch circuits 102 and 104. Based on a command from the control unit 111, the radiation signal radiated from the antenna 101 and the radiation signal radiated from the antenna 108 are distributed at a distribution ratio 1:20 in the variable distributor 105, and the bias voltage Vb1, For example, Vb2 is set to 4V and 4.5V, respectively. The reflected voltage at this time is assumed to be the initial voltage Vt0. It is assumed that the antenna 108 enters the human body proximity state 1 and the reflected voltage Vt1 becomes higher than the initial voltage Vt0. At this time, the control unit 111 starts control of the bias voltages Vb1 and Vb2 so that the reflected voltage becomes small as in the case of communication of the mobile phone.

  Next, it is assumed that the Bluetooth communication is confirmed to be completed by the input operation unit 112 such as a button for notifying the end of the Bluetooth communication. The input operation unit 112 transmits the information to the control unit 111, and the control unit 111 switches between the switch circuit 102 and the switch circuit 104. Based on a command from the control unit 111, the wave radiated from the antenna 101 and the wave radiated from the antenna 108 are distributed at a distribution ratio 20: 1 in the variable distributor 105, and the bias voltages Vb1 and Vb2 of the variable matching circuit 109 are For example, it is set to 3V and 3.5V, respectively.

  In this embodiment, the antennas 101 and 108 provided for each communication are referred to as feeding antennas, and the other antennas are referred to as auxiliary antennas. For example, when performing communication with a mobile phone, the antenna 101 serves as a feeding antenna and the antenna 108 serves as an auxiliary antenna. Similarly, when performing communication by Bluetooth, the antenna 108 is a feeding antenna and the antenna 101 is an auxiliary antenna.

  FIG. 5 is a flowchart showing an impedance matching circuit control process (main routine) executed by the portable radio apparatus of FIG. In FIG. 5, first, in step S1, an initial value 0 is set to the parameter i of the distribution ratio update process. In step S2, predetermined initial values are set for the absolute initial change amount Δ, the end determination value Δ, and the reflection voltage Vt0. In step S3, the absolute initial change amount Δ0 is set as the initial change amount Δ. In step S4, an initial value 1 is set in the codes S1, S2 and S3. In step S5, the signal intensity detection unit 106 acquires the reflected voltage Vt1. In step S6, it is determined whether or not the reflected voltage Vt1 is greater than the reflected voltage Vt0. If Vt1> Vt0, the process proceeds to step S7, and if Vt1 ≦ Vt0, the process returns to step S5.

  In step S7, an initial change amount Δ is set for each of the change amounts Δ1 and Δ2. In step S8, update, evaluation and end determination processing (FIG. 6) of the bias voltage Vb1 is executed. Here, the bias voltage Vb1 is changed so that the reflected voltage Vt2 becomes small. In step S9, update, evaluation and end determination processing (FIG. 7) of the bias voltage Vb2 is executed. Here, the bias voltage Vb2 is changed so that the reflected voltage Vt2 becomes small. In step S10, as shown in Expression (1), half the initial change amount Δ is calculated, and the calculation result is updated as the initial change amount Δ.

[Equation 1]
Δ ← Δ / 2 (1)

  In step S11, it is determined whether or not the initial change amount Δ is smaller than the end determination value EV. If Δ <EV, the process proceeds to step S12. If Δ ≧ EV, the process returns to step S7. In step S12, distribution ratio update processing (FIG. 8) is executed. In step S13, the absolute initial change amount Δ0 is set as the initial change amount Δ, and the process returns to step S7. Further, processing of each subroutine in FIG. 5 (FIGS. 6 to 8) will be described in detail below.

  FIG. 6 is a flowchart showing the update, evaluation, and end determination process (step S8) of the bias voltage Vb1, which is a subroutine of FIG. In FIG. 6, first, in step S21, (sign S1 × change amount Δ1) is added to the bias voltage Vb1, and the addition result is set as the bias voltage Vb1. In step S22, the control unit 111 applies the bias voltage Vb1 to the variable capacitance diode D1, and the signal intensity detection unit 106 acquires the reflected voltage Vt2. In step S23, it is determined whether or not the reflected voltage Vt2 is smaller than the reflected voltage Vt0. If Vt2 <Vt0, the impedance matching circuit control process is terminated, and if Vt2 ≧ Vt0, the process proceeds to step S24.

  In step S24, it is determined whether or not the reflected voltage Vt2 is smaller than the reflected voltage Vt1, and if Vt2 <Vt1, the process proceeds to step S25, and if Vt2 ≧ Vt1, the process proceeds to step S26. In step S25, the reflection voltage Vt2 is set to the reflection voltage Vt1. In step S26, the sign S1 is inverted as shown in equation (2).

[Equation 2]
S1 ← (−1) × S1 (2)

  In step S27, (2 × sign S1 × change amount Δ1) is added to the bias voltage Vb1, and the addition result is set as the bias voltage Vb1. In step S28, it is determined whether or not the bias voltage Vb1 is greater than 0. If Vb1> 0, the process proceeds to step S29. If Vb1 ≦ 0, the bias voltage Vb1 is not updated and the process proceeds to step S34. In step S29, the control unit 111 applies the bias voltage Vb1 to the variable capacitance diode D1, and the signal intensity detection unit 106 acquires the reflected voltage Vt2. In step S30, it is determined whether or not the reflected voltage Vt2 is smaller than the reflected voltage Vt0. If Vt2 <Vt0, the impedance matching circuit control process is terminated, and if Vt2 ≧ Vt0, the process proceeds to step S31.

  In step S31, it is determined whether or not the reflected voltage Vt2 is smaller than the reflected voltage Vt1, and if Vt2 <Vt1, the process proceeds to step S25, and if Vt2 ≧ Vt1, the process proceeds to step S32. In step S32, the sign S1 is inverted as shown in equation (2). In step S33, (symbol S1 × change amount Δ1) is added to the bias voltage Vb1, and the addition result is set as the bias voltage Vb1. In step S34, half the amount of change Δ1 is calculated as in equation (3), and the calculated value is updated as the amount of change Δ1.

[Equation 3]
Δ1 ← Δ1 / 2 (3)

  In step 35, it is determined whether or not the change amount Δ1 is smaller than the end determination value EV. If Δ1 <EV, the process returns to the original main routine, and if Δ1 ≧ EV, the process returns to step S21.

  FIG. 7 is a flowchart showing update, evaluation, and end determination processing (step S9) of the bias voltage Vb2, which is a subroutine of FIG. In FIG. 7, first, in step S41, (symbol S2 × change amount Δ2) is added to the bias voltage Vb2, and the addition result is set to the bias voltage Vb2. In step S42, the control unit 111 applies the bias voltage Vb2 to the variable capacitance diode D2, and the signal intensity detection unit 106 acquires the reflected voltage Vt2. In step S43, it is determined whether or not the reflected voltage Vt2 is smaller than the reflected voltage Vt0. If Vt2 <Vt0, the impedance matching circuit control process is terminated, and if Vt2 ≧ Vt0, the process proceeds to step S44.

  In step S44, it is determined whether or not the reflected voltage Vt2 is smaller than the reflected voltage Vt1, and if Vt2 <Vt1, the process proceeds to step S45, and if Vt2 ≧ Vt1, the process proceeds to step S46. In step S45, the reflection voltage Vt2 is set to the reflection voltage Vt1. In step S46, the sign S2 is inverted as shown in the equation (4).

[Equation 4]
S2 ← (−1) × S2 (4)

  In step S47, (2 × sign S2 × change amount Δ2) is added to the bias voltage Vb2, and the addition result is set to the bias voltage Vb2. In step S48, it is determined whether or not the bias voltage Vb2 is greater than 0. If Vb2> 0, the process proceeds to step S49. If Vb2 ≦ 0, the bias voltage Vb2 is not updated and the process proceeds to step S54. In step S49, the control unit 111 applies the bias voltage Vb2 to the variable capacitance diode D2, and the signal intensity detection unit 106 acquires the reflected voltage Vt2. In step S50, it is determined whether or not the reflected voltage Vt2 is smaller than the reflected voltage Vt0. If Vt2 <Vt0, the impedance matching circuit control process is terminated, and if Vt2 ≧ Vt0, the process proceeds to step S51.

  In step S51, it is determined whether or not the reflected voltage Vt2 is smaller than the reflected voltage Vt1, and if Vt2 <Vt1, the process proceeds to step S45, and if Vt2 ≧ Vt1, the process proceeds to step S52. In step S52, the sign S2 is inverted as shown in Expression (4). In step S53, (symbol S2 × change amount Δ2) is added to the bias voltage Vb2, and the addition result is set to the bias voltage Vb2. In step S54, as shown in Expression (5), half the change amount Δ2 is calculated, and the calculation result is updated as the change amount Δ2.

[Equation 5]
Δ2 ← Δ2 / 2 (5)

  In step S55, it is determined whether or not the change amount Δ2 is smaller than the end determination value EV. If Δ2 <EV, the process returns to the original main routine, and if Δ2 ≧ EV, the process returns to step 41.

  FIG. 8 is a flowchart showing distribution ratio update processing (step S12), which is a subroutine of FIG. The distribution ratio of the variable distributor 105 (ratio of the signal power radiated from the feeding antenna and the signal power radiated from the auxiliary antenna) is R1: R2. In FIG. 8, first, 1 is added to the parameter i in step S61, and the addition result is set to the parameter i. In step S62, it is determined whether or not the parameter i is equal to 1. If i = 1, the process proceeds to step S63, and if i ≠ 1, the process proceeds to step S65. That is, in the case of the first distribution ratio update process, the process proceeds to step S63, and in the case of the second and subsequent distribution ratio update processes, the process proceeds to step S65. In step 63, the reflection voltage Vt1 is set to the reflection voltage Vt3. In step 64, 1 is added to the distribution ratio parameter R2, the addition result is set to the distribution ratio parameter R2, and the process returns to the original main routine.

  In step S65, it is determined whether or not the distribution ratio DR of the variable distributor 105 is equal to 1. If DR = 1, the impedance matching circuit control process is terminated, and if DR ≠ 1, the process proceeds to step S66. In step S66, it is determined whether or not the reflected voltage Vt1 is smaller than the reflected voltage Vt3. If Vt1 <Vt3, the process proceeds to step S67, and if Vt1 ≧ Vt3, the process proceeds to step S69. In step S67, the reflection voltage Vt1 is set to the reflection voltage Vt3. In step S68, the code S3 is added to the distribution ratio parameter R2, and the addition result is set to the distribution ratio parameter R2.

  In step S69, it is determined whether or not the sign S3 is positive. If S3 is positive, the process proceeds to step 70. If S3 ≦ 0, the impedance matching circuit control process is terminated. In step S70, the sign S3 is inverted as shown in equation (6).

[Equation 6]
S3 ← (−1) × S3 (6)

  In step S71, (2 × S3) is added to the distribution ratio parameter R2, and the addition result is set to the distribution ratio parameter R2. In step S72, it is determined whether or not the distribution ratio parameter R2 is negative. If the distribution ratio parameter R2 is negative, the distribution ratio is not updated, and the impedance matching circuit control process is terminated. Return to the main routine.

  In the first embodiment described above, since the impedance can always be adaptively controlled in various environments in which the antenna 101 and the antenna 108 are placed, loss due to impedance mismatch loss can be reduced, and stable communication is possible. There is a specific effect that it is possible to perform high-quality communication.

  Furthermore, by adjusting the amount of power applied to the variable matching circuit 109 by the variable distributor 105, damage to elements (for example, variable capacitance diodes) that may be damaged when large power included in the variable matching circuit 109 is applied. It has a unique effect of preventing and stably controlling.

  Furthermore, when the feeding antenna and the auxiliary antenna are connected by the variable distributor 105, by adjusting the reverse bias voltage applied to the variable load element (variable capacitance diode in the present embodiment) of the variable matching circuit 109, The phase and amplitude of the radio signal radiated and reflected from the auxiliary antenna can be adjusted, and the variable distributor 105 can adjust the amplitude of the radio signal radiated and reflected from the auxiliary antenna. Therefore, by connecting the feeding antenna and the auxiliary antenna with the variable distributor 105, unlike when the variable distributor 105 does not connect the feeding antenna and the auxiliary antenna, the reflected signal of the feeding antenna is incident on the feeding antenna from the auxiliary antenna. Since it is possible to cancel the signal and the reflected signal of the auxiliary antenna and the incident signal from the feeding antenna to the auxiliary antenna, there is a specific effect that the adjustment range for adjusting the impedance of the antennas 101 and 108 can be expanded.

  In addition, when the reflected voltage is acquired, the control unit 111 can perform averaging, so that there is a specific effect that the reflected voltage that is an evaluation criterion for control can be stably acquired.

  In the first embodiment described above, the initial change amount Δ, the change amount Δ1, and the change amount Δ2 are updated by half as shown in the equations (1), (3), and (5), respectively. However, the present invention is not limited to this, and may be updated to 1/3. In addition, the update may be subtracted so as to decrease by 0.1V or decrease by 0.5V instead of dividing by a factor of 1/2 or 1/3.

  In the first embodiment described above, the control is started when the reflected voltage becomes higher than Vt0 and the control is performed so that the reflected voltage becomes smaller. However, the present invention is not limited to this, and the VSWR (voltage standing wave ratio) is controlled. ) May be controlled to be small.

  In the first embodiment, the bias voltage control method shown in FIGS. 5 to 8 is used. However, the present invention is not limited to this, and other methods such as a genetic algorithm may be used.

  In the first embodiment described above, the antenna 101 and the antenna 108 are a communication antenna for a mobile phone and a communication antenna for Bluetooth, respectively, but the present invention is not limited to this, and other communication such as a wireless LAN and a digital TV is possible. A combination with a general antenna may be used. Further, the antenna 101 and the antenna 108 may be communication antennas of the same mobile phone and may be a combination having different communication frequencies. Further, the antenna 101 and the antenna 108 may be a communication antenna of the same mobile phone, and a combination with the same communication frequency may be used.

  In the first embodiment described above, two antennas are used. However, the present invention is not limited to this, and there may be three or more antennas.

  In the first embodiment described above, the connection state of the switch circuit 102 and the switch circuit 104 is set to be used for communication of a mobile phone in the standard state, and the connection is switched when the input operation unit 112 detects communication by Bluetooth. Although configured, the present invention is not limited to this.

  In the first embodiment described above, the configuration of the variable matching circuit 109 is configured as shown in FIG. 2 using a variable capacitance diode whose capacitance value changes when a reverse bias voltage is applied. It is not limited to.

  In the first embodiment described above, the variable matching circuit 109 has only a variable capacitor. However, the present invention is not limited to this, and only the variable inductor may be used, and both the variable capacitor and the variable inductor may be used.

  In the first embodiment described above, the initial state of the variable matching circuit 109 is the state in which the antenna 101 or the antenna 108 can achieve impedance matching in free space. However, the present invention is not limited to this, and when the human body is in proximity. The impedance matching may be achieved in other states. Therefore, at this time, since the antenna 101 or the antenna 108 is impedance mismatched in the free space, the variable matching circuit 109 is also controlled in the free space.

  In the first embodiment described above, the variable matching circuit 109 is provided with one variable capacitance diode in series and in parallel as shown in FIG. 2, but the present invention is not limited to this, and only in series or in parallel. May be provided alone, in series, or in parallel.

  In the first embodiment described above, the directional coupler 131 is used in FIG. 4, but the present invention is not limited to this, and other devices such as a circulator may be used. Further, the signal intensity detection unit 106 is not limited to the configuration of FIG.

  In the above first embodiment, the distribution ratio of the variable distributor 105 (waves radiated from the antenna 101: waves radiated from the antenna 108) is specified with specific numerical values such as 20: 1. Is not limited to this.

  In the first embodiment described above, the reflected voltage is averaged and acquired by the control unit 111. However, the present invention is not limited to this, and the signal intensity detection unit 106 and the control unit 111 as shown in FIGS. RC or RL integrating circuits 151 and 152 may be provided between the two, and the voltage Vc of the capacitor C1 or the voltage Vr of the resistor R2 may be detected. By so doing, the change in the reflected voltage becomes smooth, and a stable reflected voltage can be acquired.

  In the first embodiment described above, the control is terminated when the distribution ratio becomes equal in step S65 (FIG. 8) of the distribution ratio update process in step S12. However, the present invention is not limited to this, and the ratio is 4: 1. The reference value for ending may be freely set, for example, ending when the relationship is satisfied.

  In the first embodiment described above, the transmission system has been described. However, the present invention is not limited to this, and control is performed so that the received power detected by the signal strength detector 132 of the signal strength detector 113 is increased. By doing so, it can also be applied to a receiving system.

Second embodiment.
FIG. 11 is a block diagram showing a configuration of a portable radio apparatus equipped with the impedance matching apparatus according to the second embodiment of the present invention. In FIG. 11, an antenna 101 is a communication antenna for a mobile phone, and an antenna 108 is a digital television antenna.

  First, a case where communication is performed using a mobile phone will be described. When information indicating that mobile phone communication or digital television communication is to be terminated is input from the input operation unit 112B, the input operation unit 112B transmits the information to the control unit 111A. Based on the information, control unit 111A switches switch circuit 141 as follows. Here, the switch circuit 141 includes two switches 141a and 141b. A termination resistor 141R1 is connected to the contact b of the switch 141a, and a termination resistor 141R2 is connected to the contact b of the switch 141b. In this case, the switches 141a and 141b are switched to the contacts a and a, respectively.

  The wireless signal generated by the wireless transmission circuit 107 is input to the variable distributor 105 via the signal strength detector 106 and the circulator 120, and the variable distributor 105 distributes the input wireless signal with a predetermined power distribution ratio. Thereafter, one of the wireless signals to which power has been distributed is output and radiated to the antenna 101 via the matching circuit 103, while the other wireless signal to which power has been distributed is transmitted to the antenna 108 via the switch 141a and the variable matching circuit 109A. Output and radiate. Here, the variable matching circuit 109A may be the circuit of FIG. 3 or the circuit of FIG.

  In the present embodiment, signal strength detection is performed on the signal intensity of the combined signal of the reflected signal from the antenna 101 and the antenna 108, the incident signal from the antenna 101 to the antenna 108, and the incident signal from the antenna 108 to the antenna 101. The signal is detected by the unit 106 and the detected signal intensity is transmitted to the control unit 111A. The control unit 111A controls to change the reverse bias voltage applied to the variable capacitance diodes D1 and D2 (FIG. 2) of the variable matching circuit 109A so that the detected signal strength is substantially minimized. The controller 111A also controls the distribution ratio of the variable distributor 105 as will be described in detail later. At the time of reception, the radio signals received by the antennas 101 and 108 are input to the radio reception circuit 114 via the signal intensity detector 113 via the circulator 120 and then demodulated. Here, the control unit 111A includes the circulator The reverse bias applied to the variable capacitance diodes D1 and D2 (FIG. 2 or FIG. 3) of the variable matching circuit 109A so that the signal strength of the reception radio signal input from 120 to the signal strength detector 113 is substantially maximized. Control to change the voltage.

  Next, a case where a digital television system television signal is received will be described. When information for receiving digital television is input from the input operation unit 112B, the input operation unit 112B transmits the information to the control unit 111A. Based on the information, control unit 111A switches switch circuit 141 as follows. Here, the switches 141a and 141b are switched to the contacts b and b, respectively.

  The television signal received by the antenna 108 is input to the television receiving circuit 114A via the variable matching circuit 109A, the switch 141b, and the signal strength detector 113A, and signal processing including demodulation processing is executed. The television signal received by the antenna 108 is detected by the signal strength detector 113A, and the detected signal strength is transmitted to the control unit 111A. The controller 111A applies the variable capacitance diodes D1 and D2 (FIG. 2 or 3) of the variable matching circuit 109A so that the signal strength of the received television signal input to the signal strength detector 113A is substantially maximized. The reverse bias voltage to be controlled is changed.

  A method for adaptively matching the impedance of the antenna 101 and the antenna 108 in various environments in the portable radio apparatus configured as described above will be described. Assume that the antenna 101 is impedance-matched in free space by the matching circuit 103. During the operation of the wireless transmission circuit 107, the wireless signal generated by the wireless transmission circuit 107 is transmitted to the antenna 101 via the directional coupler 131, the circulator 120, the variable distributor 105, and the matching circuit 103 of the signal strength detection unit 106. Is output and emitted. Further, the radio signal distributed by the variable distributor 105 is output and radiated to the antenna 108 via the switch 141a and the variable matching circuit 109A. At this time, the power distribution ratio between the radio signal radiated from the antenna 101 and the radio signal radiated from the antenna 108 is, for example, 20: 1.

  The signal strength detector 132 of the signal strength detection unit 106 detects the reflected voltage of the reflected signal reflected and returned from the antennas 101 and 108, and transmits the detected reflected voltage to the control unit 111A. This reflected voltage is Vt0. In the present embodiment, Vt0 is defined as a reflected voltage value that the antenna 101 or 108 considers to be in free space. For example, even if the antenna 101 or 108 is in free space, the reflected voltage varies slightly depending on the surrounding environment, but when the reflected voltage Vt0 does not exceed 1V, the reflected voltage Vt0 is set to 1V. The reflected voltage Vt0 is an average value of several values acquired by the signal intensity detector 106.

  When the antenna 101 is close to a human body, impedance mismatch of the antenna 101 occurs, a reflected signal from the antenna 101 is generated, and the signal returns to the directional coupler 131 of the signal intensity detector 106. In addition, the reflected signal from the antenna 108, the incident signal radiated from the antenna 101 and incident on the antenna 108, and the incident signal radiated from the antenna 108 and incident on the antenna 101 return to the directional coupler 131 of the signal intensity detector 106. Come. At this time, the reflected signal from the antenna 101 and the incident signal radiated from the antenna 108 and incident on the antenna 101 and the reflected signal from the antenna 108 and the incident signal radiated from the antenna 101 and incident on the antenna 108 are combined in the variable distributor 105. Synthesized in a 20: 1 ratio. The signal intensity detector 132 of the signal intensity detector 106 detects the reflected voltage and transmits the detected reflected voltage to the controller 111A.

  Here, the reflected signal from the antenna 101 and the incident signal radiated from the antenna 108 and incident on the antenna 101 are combined with the reflected signal from the antenna 108 and the incident signal radiated from the antenna 101 and incident on the antenna 108 at a distribution ratio of 20: 1. The combined signal is a reflected signal from the antenna 101 and an incident signal that is radiated from the antenna 108 and incident on the antenna 101, and 1/21 is a reflected signal from the antenna 108 and the antenna. The incident signal radiated from 101 and incident on the antenna 108 is included. Here, when the reflected voltage Vt1 becomes larger than the reflected voltage Vt0, the control unit 111A starts to control the bias voltages Vb1 and Vb2 so that the reflected voltage becomes smaller. This state is referred to as a human body proximity state 1. Control of the bias voltages Vb1 and Vb2 will be described in detail with reference to FIGS.

  Next, it is assumed that reception of the television signal is selected by the input operation unit 112B such as a button for instructing reception start of the television signal. The input operation unit 112B transmits the information to the control unit 111A, and the control unit 111A switches both the switches 141a and 141b of the switch circuit 141 to the contact point b. The bias voltages Vb1 and Vb2 of the variable matching circuit 109A are applied so that the antenna 108 can achieve impedance matching in free space. The received power at this time is assumed to be Vt0. It is assumed that the antenna 108 enters the human body proximity state 1 and the received power Vt1 is greater than the received power Vt0. At this time, the control unit 111A starts to control the bias voltages Vb1 and Vb2 so that the received power becomes maximum.

  Next, it is assumed that the reception of the television signal is confirmed by the input operation unit 112B such as a button for notifying the completion of the reception of the television signal. The input operation unit 112B transmits the information to the control unit 111A, and the control unit 111A switches both the switches 141a and 141b of the switch circuit 141 to the contact point a. Based on a command from the control unit 111A, the radio signal radiated from the antenna 101 and the radio signal radiated from the antenna 108 are distributed at a distribution ratio of 20: 1 in the variable distributor 105, and the control unit 111A detects the signal intensity detector 106. The bias voltages Vb1 and Vb2 of the variable matching circuit 109A are impedance-matched in the free space so that the reflected voltage from the signal is substantially minimized and the received power from the signal strength detector 113 is substantially maximized. Applied to take.

  In this embodiment, an antenna set for each communication is called a feeding antenna, and the other antennas are called auxiliary antennas. For example, when performing communication with a mobile phone, the antenna 101 serves as a feeding antenna and the antenna 108 serves as an auxiliary antenna. Similarly, when a television signal is received, the antenna 108 is a feeding antenna and the antenna 101 is an auxiliary antenna.

  FIG. 12 is a flowchart showing an impedance matching circuit control process (main routine) executed by the portable wireless device of FIG. In FIG. 12, first, in step S1, an initial value 0 is set to the parameter i of the distribution ratio update process. In step S2, predetermined initial values are set for the absolute initial change amount Δ, the end determination value Δ, and the reflection voltage Vt0. In step S3, the absolute initial change amount Δ0 is set as the initial change amount Δ. In step S4A, an initial value 1 is set in the codes S1 and S2. In step S5, the signal intensity detection unit 106 acquires the reflected voltage Vt1. In step S6, it is determined whether or not the reflected voltage Vt1 is greater than the reflected voltage Vt0. If Vt1> Vt0, the process proceeds to step S7, and if Vt1 ≦ Vt0, the process returns to step S5.

  In step S7, an initial change amount Δ is set as the change amounts Δ1 and Δ2. In step S8, update, evaluation and end determination processing (FIG. 6) of the bias voltage Vb1 is executed. Here, the bias voltage Vb1 is changed so that the reflected voltage Vt2 becomes small. In step S9, update, evaluation and end determination processing (FIG. 7) of the bias voltage Vb2 is executed. Here, the bias voltage Vb2 is changed so that the reflected voltage Vt2 becomes small. In step S10, a half of the initial change amount Δ is calculated as in equation (1), and the calculation result is updated as the initial change amount. In step S11, it is determined whether or not the initial change amount Δ is smaller than the end determination value EV. If Δ <EV, the impedance matching circuit control process is ended, and if Δ ≧ EV, the process returns to step S7. The processing of each subroutine in FIG. 12 (FIGS. 6 and 7) is the same as that in the first embodiment, and thus description thereof is omitted.

  In the second embodiment described above, since the impedance can always be adaptively controlled in various environments where the antenna 101 and the antenna 108 are placed, it is possible to reduce the loss due to the impedance mismatching loss and stably communicate. There is a specific effect that it is possible to perform high-quality communication.

  Furthermore, by adjusting the amount of power applied to the variable matching circuit 109A by the variable distributor 105, damage to an element (for example, a variable capacitance diode) that may be damaged when a large amount of power included in the variable matching circuit 109A is applied. It has a unique effect of preventing and stably controlling.

  Further, when the feeding antenna and the auxiliary antenna are connected by the variable distributor 105, the auxiliary antenna is adjusted by adjusting the reverse bias voltage applied to the variable load element (variable capacitance diode in the present embodiment) of the variable matching circuit 109A. The phase and amplitude of the radio signal radiated and reflected from the auxiliary antenna can be adjusted, and the variable distributor 105 can adjust the amplitude of the radio signal radiated and reflected from the auxiliary antenna. Therefore, by connecting the feeding antenna and the auxiliary antenna with the variable distributor 105, unlike when the variable distributor 105 does not connect the feeding antenna and the auxiliary antenna, the reflected signal of the feeding antenna is incident on the feeding antenna from the auxiliary antenna. Since it is possible to cancel the signal and the reflected signal of the auxiliary antenna and the incident signal from the feeding antenna to the auxiliary antenna, there is a specific effect that a range in which the impedances of the antennas 101 and 108 are adjusted can be increased.

  In addition, when the reflected voltage and the received power are acquired, the control unit 111A performs averaging, so that there is a specific effect that the reflected voltage and the received power that are evaluation criteria for control can be stably acquired.

  In the second embodiment described above, the initial change amount Δ, the change amount Δ1, and the change amount Δ2 are updated to half as shown in the equations (1), (3), and (5). However, the present invention is not limited to this, and may be updated to 1/3. In addition, the update may be subtracted so as to decrease by 0.1V or decrease by 0.5V instead of dividing by a factor of 1/2 or 1/3.

  In the second embodiment described above, the control is started when the reflected voltage becomes larger than Vt0, and the control is performed so that the reflected voltage becomes smaller. However, the present invention is not limited to this, and the VSWR (voltage standing wave ratio) is controlled. ) May be controlled to be small.

  In the second embodiment described above, the bias voltage control method shown in FIGS. 6, 7 and 12 is used. However, the present invention is not limited to this, and other methods such as a genetic algorithm may be used. Good.

  In the above second embodiment, the antenna 101 and the antenna 108 are a mobile phone communication antenna and a television signal receiving antenna, respectively. However, the present invention is not limited to this, and other antennas for communication are used. It may be a combination.

  In the above second embodiment, two antennas are used. However, the present invention is not limited to this, and there may be three or more antennas.

  In the above second embodiment, the connection state of the switch circuit 141 is set to be used for communication of a mobile phone in the standard state, and the connection is switched when the input operation unit 112 detects communication by a digital television. The present invention is not limited to this.

  In the above second embodiment, the configuration of the variable matching circuit 109A is configured as shown in FIG. 3 using a variable capacitance diode whose capacitance value is changed by applying a reverse bias voltage. However, the present invention is not limited to this. Absent.

  In the second embodiment described above, the variable matching circuit 109A is configured with only the variable capacitor. However, the present invention is not limited to this, and only the variable inductor may be used, and both the variable capacitor and the variable inductor may be used.

  In the second embodiment described above, the initial state of the variable matching circuit 109A is the state in which the antenna 101 or the antenna 108 can achieve impedance matching in free space. However, the present invention is not limited to this, and when the human body is in proximity, etc. The impedance matching may be achieved in other states. Therefore, at this time, since the antenna 101 or the antenna 108 becomes impedance mismatched in the free space, the variable matching circuit 109A is controlled also in the free space.

  In the above second embodiment, as shown in FIG. 3, the variable matching circuit 109A is provided with one variable capacitance diode in series and in parallel, but the present invention is not limited to this, and only in series or in parallel. May be provided alone, in series, or in parallel.

  In the second embodiment described above, the directional coupler 131 is used in FIG. 4, but the present invention is not limited to this, and other devices such as a circulator may be used. Further, the signal intensity detection unit 106 is not limited to the configuration of FIG.

  In the second embodiment described above, the distribution ratio of the variable distributor 105 (waves radiated from the antenna 101: waves radiated from the antenna 108) is specified with specific numerical values such as 20: 1. Is not limited to this.

  In the second embodiment described above, the reflected voltage and the received power are obtained by averaging in the control unit 111A. However, the present invention is not limited to this, and the signal intensity detection unit 106 as shown in FIGS. Further, RC or RL integrating circuits 151 and 152 may be provided between the control unit 111A and the voltage Vc of the capacitor C1 or the voltage Vr of the resistor R2 may be detected. By so doing, changes in the reflected voltage and received power become smooth, and a stable reflected voltage and received power can be acquired. By averaging the received power, fluctuations in the received power due to fading can be suppressed.

  In the above second embodiment, the transmission system has been described. However, the present invention is not limited to this, and control is performed so as to increase the received power detected by the signal strength detector 132 of the signal strength detector 113. By doing so, it can also be applied to a receiving system.

  In the above second embodiment, the receiving circuit is divided into the radio receiving circuit 114 for the mobile phone and the television receiving circuit 114A for the digital television. However, the present invention is not limited to this, and the receiving circuit is not limited thereto. One may be used.

  In the above second embodiment, the variable element (variable capacitance diode) and the fixed element are combined. However, the present invention is not limited to this, and only the variable element as shown in FIG. 2 of the first embodiment. You may comprise.

Modified example.
FIG. 13 is a diagram showing a circuit configuration of a part of a variable matching circuit of a portable wireless device equipped with an impedance matching device which is a modification of the second embodiment according to the present invention. In the second embodiment described above, a part of the variable matching circuit 109A is configured by the variable capacitance diodes D1 and D2 whose capacitance can be changed by changing the voltage. It is composed of elements C11, C12, C13, C14 having fixed values and switches SW1, SW2, SW3, SW4. In FIG. 13, the switch controller 150 switches the switches SW1, SW2, SW3, and SW4 based on a command from the control unit, and thus has functions and effects equivalent to those of the variable capacitance diodes D1 and D2.

  As described above in detail, according to the impedance matching device and the wireless communication terminal device using the impedance matching device according to the present invention, the impedance can always be adaptively controlled in various environments where the antenna is placed. Loss can be reduced, and wireless communication with good communication quality can be performed stably. Also, by controlling the variable matching means connected to the auxiliary antenna mounted separately from the feeding antenna (specifically, controlling the reverse bias voltage to the variable capacitance diode to control the impedance conversion ratio) Therefore, it is possible to prevent a large amount of power from being applied to the variable matching means, thereby preventing the element from being damaged and stably controlling impedance matching.

It is a block diagram which shows the structure of the portable radio | wireless apparatus carrying the impedance matching apparatus which is 1st Embodiment based on this invention. FIG. 2 is a circuit diagram illustrating a configuration of a variable matching circuit 109 in FIG. 1. FIG. 12 is a circuit diagram showing a configuration of a variable matching circuit 109A of FIG. It is a block diagram which shows the structure of the signal strength detection part 106 of FIG. It is a flowchart which shows the impedance matching circuit control process (main routine) performed by the portable radio | wireless apparatus of FIG. 13 is a flowchart showing update, evaluation, and end determination processing (step S8) of the bias voltage Vb1, which is a subroutine of FIGS. 5 and 12. 13 is a flowchart showing update, evaluation, and end determination processing (step S9) of the bias voltage Vb2, which is a subroutine of FIGS. 5 and 12. 6 is a flowchart showing distribution ratio update processing (step S12), which is a subroutine of FIG. 5; It is a circuit diagram which shows the structure of the RC integration circuit which is a part of portable radio | wireless apparatus carrying the impedance matching apparatus which is a modification of 1st Embodiment based on this invention. It is a circuit diagram which shows the structure of the RL integrating circuit which is a part of portable radio | wireless apparatus carrying the impedance matching apparatus which is a modification of 1st Embodiment based on this invention. It is a block diagram which shows the structure of the portable radio | wireless apparatus carrying the impedance matching apparatus which is 2nd Embodiment concerning this invention. It is a flowchart which shows the impedance matching circuit control process (main routine) performed by the portable radio | wireless apparatus of FIG. It is a figure which shows the circuit structure of a part of variable matching circuit of the portable radio | wireless apparatus carrying the impedance matching apparatus which is a modification of 2nd Embodiment which concerns on this invention.

Explanation of symbols

101, 108 ... antenna,
102, 104, 141 ... switch circuit,
102a, 102b, 102c, 104a, 104b, 104c, 141a, 141b ... switches,
103, 110 ... matching circuit,
105: Variable distributor,
106, 113, 113A ... signal intensity detector,
107: wireless transmission circuit,
109, 109A ... variable matching circuit,
111, 111A ... control unit,
112, 112B ... input operation unit,
114 ... a wireless receiving circuit,
114A ... Television receiver circuit,
120 ... circulator,
121, 122 ... Bias voltage generator,
131 ... Directional coupler,
132: Signal strength detector,
151, 152 ... integrating circuit,
150: Switch controller D1, D2: Variable capacitance diode,
L1, L11, L12, L21, L22 ... inductors,
Z1 ... Series load element,
Z2: Parallel load element,
R1, R2 ... resistors C1, C11, C12, C13, C14 ... capacitors,
SW1, SW2, SW3, SW4 ... switch.

Claims (5)

An impedance matching device that performs impedance matching between a plurality of antennas including a first antenna and a second antenna and a wireless communication circuit,
The wireless signal from the wireless communication circuit is distributed to a plurality of wireless signals at a predetermined distribution ratio different from 1, and a first wireless signal is output among the distributed wireless signals, while the distributed wireless Distribution means for outputting a second radio signal different from the first radio signal among the signals;
Variable matching means for executing impedance conversion processing with a predetermined impedance conversion ratio on the first or second radio signal output from the distributing means, and outputting and radiating to the first or second antenna;
Signal detection means for detecting a level of a reflected wave signal reflected on the distribution means when a radio signal from the radio communication circuit is radiated from the first and second antennas;
Control means for changing the impedance conversion ratio of the variable matching means based on the level of the reflected wave signal detected by the signal detection means so that the level of the reflected wave signal is substantially minimized. An impedance matching device. When the distribution ratio is set so that the level of the first radio signal is higher than the level of the second radio signal, the first radio signal from the distribution means is converted into a first impedance matching circuit. A first state in which the second radio signal from the distributing means is output and radiated to the second antenna via the variable matching means; ,
When the distribution ratio is set so that the level of the first radio signal is lower than the level of the second radio signal, the second radio signal from the distribution means is converted into a second impedance matching circuit. A second state in which the first radio signal from the distributing means is output and radiated to the first antenna via the variable matching means; The impedance matching apparatus according to claim 1, further comprising switching means for selectively switching between. The distribution unit combines the radio signal received by the first antenna and the radio signal received by the second antenna and then input through the variable matching unit, and combines the radio signal with the radio communication circuit. Output to
The signal detection means detects the level of the synthesized radio signal output from the distribution means,
The control means, based on the level of the synthesized radio signal detected by the signal detection means, has an impedance conversion ratio of the variable matching means so that the level of the synthesized radio signal is substantially maximized. The impedance matching device according to claim 1, wherein the impedance matching device is changed.   4. The signal detecting unit according to claim 1, wherein the signal detecting unit includes an integrating circuit, and outputs a level obtained by temporally integrating the level of the detected signal by the integrating circuit to the control unit. The impedance matching device described in 1. The impedance matching device according to any one of claims 1 to 4,
A radio communication apparatus comprising: a radio communication circuit that generates a radio signal to be transmitted and outputs the radio signal to the impedance matching apparatus while receiving and receiving a radio signal received from the impedance matching apparatus.

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