JP2008011341A - Mobile wireless terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mobile wireless terminal capable of automatically matching impedance between a transmission/reception circuit and an antenna, with a simple configuration. <P>SOLUTION: In a receiver 113 of a mobile phone 1, a logical circuit 108 applies a voltage to a matching circuit 106 whose impedance is variable, so that the power intensity of the signal received from an antenna 101 becomes maximum. In a transmitter 112, a control circuit 110 calculates a required variation of transmission frequency based on a pre-held database, according to the value of applied voltage. A matching circuit corresponding to the variation is selected for use from among matching circuits 103a-e. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a portable wireless terminal that automatically matches the impedance of an antenna, and more particularly to a technique for improving communication performance.

In recent years, wireless devices such as mobile phones are rapidly becoming smaller and thinner, and antennas are being built into the main body.
A mobile phone, which is an example of a wireless device, is mainly used in the state of being close to the human body. However, when used in this way, the impedance of the antenna changes significantly due to the influence of the human body and external objects. As a result, the reception level of the signal is greatly reduced, causing a signal error and degrading the communication quality.

As one technique for improving communication quality, an antenna automatic matching circuit is disclosed (see Patent Document 1).
According to Patent Document 1, a receiving circuit that receives a signal via an antenna measures a received signal sensitivity index (hereinafter abbreviated as RSSI), and a control circuit applies a voltage to a variable capacitance diode connected to the antenna. Thus, the reactance value of the variable capacitance diode is changed, the applied voltage is adjusted so that the RSSI measured by the receiving circuit is maximized, and the impedance between the receiving circuit and the antenna is matched. This technique can be applied to signal reception, and the impedance between the transmission circuit and the antenna does not match. Therefore, when the transmission frequency and the reception frequency are different, the communication quality at the time of transmission still deteriorates.

Regarding transmission, Patent Document 2 is disclosed as another technique for improving communication quality.
According to Patent Document 2, a wireless circuit and an antenna are connected via a matching circuit that is a variable capacitance diode, and a control circuit applies a voltage to the matching circuit to change the reactance of the matching circuit. The power detection circuit measures the power of the signal output from the wireless circuit and the power at the antenna end via the matching circuit, and the control circuit compares both power values so that the degree of power loss is minimized. The impedance between the radio circuit and the antenna is matched by adjusting the voltage applied to the matching circuit.
JP 61-135235 A JP-A-11-251928

However, according to the method disclosed in Patent Document 2, the feedback control is performed using at least two power detection circuits and one comparator in addition to the circuit for measuring the received signal sensitivity index disclosed in Patent Document 1. There is a problem that a circuit is required and the circuit configuration becomes complicated.
Further, according to Patent Document 1, a nonlinear element such as a varactor diode is used as a matching circuit of a transmission circuit. In actual use, the nonlinear element reaches a saturation region, and a stable impedance value cannot be obtained. There was a problem of causing.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a portable wireless terminal that can automatically match the impedance between a transmission / reception circuit and an antenna with a simple configuration.

  In order to solve the above problems, the present invention is a portable wireless terminal including a transmission unit and a reception unit that share the same antenna and transmit and receive based on a communication specification that defines a specified transmission frequency and a specified reception frequency. The receiving unit includes a reception matching circuit connected to the antenna and having a variable impedance, changes the impedance, maximizes the power intensity of the signal received by the antenna, and is determined by the changed impedance. And the transmission unit is connected to the antenna and has a variable impedance and a transmission matching circuit, and acquires the parameter, and based on the acquired parameter, from the specified reception frequency by changing the impedance of the reception matching circuit The amount of change in the resonance frequency of the A control circuit that calculates a required change amount of the resonance frequency from the specified transmission frequency by subtracting a difference from the specified transmission frequency, and a change circuit that changes the impedance of the transmission matching circuit according to the required change amount. Including.

The portable wireless terminal of the present invention has the above-described configuration, thereby matching the impedance of the transmission unit and the antenna with a simple configuration of changing the impedance of the transmission unit according to the parameters determined by the reception unit, Communication quality can be improved.
The transmission matching circuit includes a plurality of transmission matching elements each having a different impedance, each transmission matching element is selectively connected to the antenna, and the changing circuit has an impedance corresponding to the required change amount. A transmission matching element may be connected to the antenna.

  In addition, the control circuit stores in advance a plurality of voltage values in association with the amount of change in the resonance frequency when the voltage indicated by each voltage value is applied to the reception matching circuit, and the prescribed reception based on the communication specifications. A storage circuit that stores a frequency and a specified transmission frequency, stores a change amount of a resonance frequency that changes when each transmission matching element is connected to the antenna, and obtains a voltage value as the parameter from the reception unit The circuit and the amount of change in the resonance frequency corresponding to the acquired voltage value are read out, and the difference between the specified reception frequency and the specified transmission frequency is subtracted from the read amount of change, thereby reducing the resonance frequency from the specified transmission frequency. The change circuit includes a calculation circuit that calculates a required change amount, and a selection circuit that selects a transmission matching element having an impedance corresponding to the required change amount. , It may be connected to the selected transmitted matching element to the antenna.

The reception matching circuit may be a variable capacitance element, the parameter may be a voltage value of a voltage applied to the reception matching circuit, and the control circuit may acquire the voltage value as the parameter. .
Each of the plurality of transmission matching elements may have an inductance value corresponding to a small section obtained by dividing the voltage section from the lower limit to the upper limit of the voltage that can be applied to the reception matching circuit into the same number as the number of transmission matching elements. Good.

Each of the plurality of transmission matching elements has an average impedance value corresponding to a small section obtained by dividing the voltage section from the lower limit to the upper limit of the voltage that can be applied to the reception matching circuit into the same number as the number of transmission matching elements. It is good as well.

According to this configuration, even when a wide range of signal power is used for signal transmission, a signal can be transmitted using an impedance value corresponding to each signal power value within the range, and the transmission unit and the antenna The communication quality can be improved by matching the impedance.

  In addition, the transmission unit and the reception unit perform wireless communication with other apparatuses using a plurality of communication channels, and each communication channel is assigned a specific transmission frequency and a specific reception frequency different from those of other communication channels based on communication specifications. The storage circuit stores a plurality of voltage values in advance for each communication channel in association with a change amount of a resonance frequency when a voltage indicated by each voltage value is applied to the reception matching circuit. The prescribed reception frequency and the prescribed transmission frequency based on the specification are stored, the amount of change in the resonance frequency that changes when each transmission matching element is connected to the antenna, and the calculation circuit uses the communication channel used Read out the change amount of the resonance frequency corresponding to the acquired voltage value, and from the read change amount, the prescribed reception frequency and the prescribed transmission frequency By reducing the difference, it is also possible to calculate the required amount of change in resonance frequency from said prescribed transmission frequency.

According to this configuration, it is possible to improve communication quality by using an optimum impedance value for each of a plurality of communication channels used for communication.
Further, each of the plurality of transmission matching elements may be a linear element.
According to this configuration, since a plurality of linear elements are used, impedance can be matched using a stable impedance value that does not reach the saturation region for a wide range of transmission power, and communication quality can be improved. .

The reception matching circuit may be a linear element.
According to this configuration, it is possible to improve the communication quality by using the linear element to match the impedance with a stable impedance value that does not reach the saturation region.
Further, the receiving unit includes a directional coupler that acquires a direct wave of a signal received by the antenna and a reflected wave generated in the receiving unit, and a comparator that compares the direct wave and the reflected wave. In addition, the difference between the direct wave and the reflected wave may be maximized by changing the impedance, and a parameter for determining the changed impedance may be output.

According to this configuration, it is possible to determine the parameter that determines the impedance with a simpler configuration than in the past.
The impedance matching method of the present invention uses the same antenna, transmits and receives based on a communication specification that defines a prescribed transmission frequency and a prescribed reception frequency, and an impedance matching method used for a portable wireless terminal including a transmission unit and a reception unit The reception unit includes a reception matching circuit connected to the antenna and having a variable impedance, and the transmission unit includes a transmission matching circuit connected to the antenna and having a variable impedance, and the impedance matching method The output step of changing the impedance of the reception matching circuit to maximize the power intensity of the signal received by the antenna, outputting a parameter determined by the changed impedance, acquiring the parameter, and acquiring the parameter Based on the above, the impedance change of the reception matching circuit Therefore, the amount of change in the resonance frequency from the specified transmission frequency is estimated by estimating the amount of change in the resonance frequency from the specified reception frequency and subtracting the difference between the specified reception frequency and the specified transmission frequency from the amount of change. And a change step of changing the impedance of the transmission matching circuit in accordance with the required change amount.

  The computer program of the present invention is a computer program used for a portable wireless terminal including a transmission unit and a reception unit that shares the same antenna and transmits and receives data based on a communication specification that defines a specified transmission frequency and a specified reception frequency. The reception unit includes a reception matching circuit connected to the antenna and having a variable impedance, the transmission unit includes a transmission matching circuit connected to the antenna and having a variable impedance, and the computer program An output step of changing the impedance of the reception matching circuit to maximize the power intensity of the signal received by the antenna, outputting a parameter determined by the changed impedance, obtaining the parameter, and based on the obtained parameter, Impedance change of the reception matching circuit Therefore, the amount of resonance frequency from the specified transmission frequency is estimated by estimating the amount of change in the resonance frequency from the specified reception frequency and subtracting the difference between the specified reception frequency and the specified transmission frequency based on the communication specifications from the amount of change. A control step of calculating a change amount; and a change step of changing an impedance of the transmission matching circuit in accordance with the required change amount.

  An integrated circuit according to the present invention is an integrated circuit including a transmitter and a receiver that share the same antenna and transmit and receive based on a communication specification that defines a specified transmission frequency and a specified reception frequency. Including a reception matching circuit connected to the antenna and having a variable impedance, changing the impedance to maximize a power intensity of a signal received by the antenna, outputting a parameter for determining the changed impedance, and transmitting A transmission matching circuit connected to the antenna and having a variable impedance; and acquiring the parameter; and based on the acquired parameter, an amount of change in the resonance frequency from the specified reception frequency due to an impedance change of the reception matching circuit And the difference between the specified reception frequency and the specified transmission frequency from the amount of change. By reducing, comprising a control circuit for calculating the required amount of change in resonance frequency from said prescribed transmission frequency, and a change circuit for changing the impedance of the transmission matching circuit in accordance with the necessary amount of change.

  According to this configuration, the impedance between the transmission unit and the antenna can be matched and communication quality can be improved with a simple configuration in which the impedance of the transmission unit is changed according to the parameters determined by the reception unit.

<Overview>
The mobile phone 1 according to an embodiment of the present invention has a signal reception level that is greatly changed by a significant change in the impedance of the antenna under the influence of a human body or an external object that exists in the vicinity of the mobile phone 1. In such a case, the input / output impedance between the antenna and the transmission circuit and the input / output impedance between the antenna and the reception circuit are matched to maximize the signal level of the transmission output and the reception input. In addition, heating of the mobile phone 1 body and overvoltage discharge are prevented.

In an ideal state, the antenna of the mobile phone 1 has a frequency characteristic as shown by a frequency characteristic 301 in FIG. 2. As an example, the antenna transmits a signal using the transmission frequency Ftx and receives a signal using the reception frequency Frx. To do.
Here, the horizontal axis of FIG. 2 is frequency, and the vertical axis is RSSI (Received Signal Strength Indicator).

The RSSI is a signal indicating the intensity of the received signal, the unit is expressed in dBm, and in FIG. 2, the closer to the origin, the higher the transmission / reception level, that is, the better transmission / reception can be executed.
The cellular phone 1 transmits and receives signals using a plurality of channels, and a signal transmission frequency band, a reception frequency band, a transmission frequency, and a reception frequency are predetermined for each channel. Ftx and Frx described above indicate a transmission frequency and a reception frequency of a certain channel.

In an actual use state where a human body or the like is in proximity to the mobile phone 1, the frequency characteristic 301 changes like the frequency characteristic 302 in FIG.
For example, in the ideal state, the RSSI that is at the reception level RL1 decreases to the reception level RL2.
The cellular telephone device 1 improves the frequency characteristic 302 of FIG. 2A like the frequency characteristic 303 by controlling the matching circuit.

Here, since the mobile phone does not have a function of directly measuring the transmission frequency or the reception frequency, and usually has a function of measuring RSSI in order to display the signal strength, The improvement of the frequency characteristic is determined using RSSI.
Specifically, the mobile phone 1 repeatedly measures RSSI, and determines that the frequency characteristic is improved from the state of the frequency characteristic 302 to the state of the frequency characteristic 303 when the measured RSSI exceeds RL1. .

Although f1, f2, and fr in FIG. 2 will be described later, f1 represents the difference between the resonant frequency of the antenna in actual use and no adjustment state and the reception frequency in the ideal state, and f2 is real use and no use. The difference between the resonant frequency of the antenna in the adjusted state and the transmission frequency in the ideal state is shown.
In the mobile phone 1, the transmission power related to signal transmission is very large compared to the reception power. Therefore, a nonlinear element similar to the conventional matching circuit is used for the signal reception unit, and a plurality of transmission units are used for the transmission unit. A linear element is used.
<Configuration>
As shown in FIG. 1, the mobile phone 1 according to the embodiment includes an antenna 101, a duplexer 102, a transmission unit 112, and a reception unit 113. The transmission unit 112 includes a plurality of matching circuits 103a to 103a. e, a changeover switch 104, a transmission circuit 105, a control circuit 110, and a memory 111. A reception unit 113 includes a reception circuit 107 that outputs RSSI, a matching circuit 106, a logic circuit 108, and a D / A converter. 109.

The transmission circuit 105 is a circuit that performs control for wirelessly transmitting a signal via the antenna 101.
The duplexer 102 connected to the antenna 101 is a circuit for sharing the antenna between the transmission circuit 105 and the reception circuit 107.
Each of the matching circuits 103a to 103e is configured by only a linear element, one end is connected to a duplexer, and the other end is connected to a changeover switch.

Each of matching circuits 103a to 103e is selected according to voltage value VD1 applied to matching circuit 106.
When an appropriate matching circuit is selected and used from the matching circuits 103a to 103e, the impedance between the antenna 101 and the transmission circuit 105 is matched, and the signal is released into the air with a small loss. However, when an inappropriate matching circuit is selected and used, mismatch loss occurs between the antenna 101 and the transmission circuit 105, and a large loss occurs.

Selection of an appropriate matching circuit will be described later.
The changeover switch 104 includes switches 104a to 104e, and in accordance with a changeover instruction SW indicating any of the switches 104a to 104e acquired from the control circuit 110, the switch 104a to 104e indicated by SW is in a conductive state. That is, turn it on.

The memory 111 is a memory device for storing data written by the matching circuit 106. Information on the assigned communication channel is written in the memory 111.
The reception circuit 107 is a circuit that performs control for wirelessly receiving a signal via the antenna 101, measures the RSSI of the reception signal received via the antenna 101, the duplexer 102, and the matching circuit 106, and calculates an RSSI value. Is output to the logic circuit 108.

The logic circuit 108 monitors the RSSI value acquired from the receiving circuit 107, adjusts the value (VD1) of the voltage to be applied to the varactor diode so as to maximize the RSSI value, and outputs it to the D / A converter 109. To do.
The D / A converter 109 receives VD 1, performs D / A conversion on the received VD 1, and applies a voltage as a D / A conversion result to the matching circuit 106.

The matching circuit 106 is configured by a non-linear element such as a varactor diode, and the capacitance of the varactor diode is changed based on the voltage applied from the D / A converter 109, whereby the matching circuit 106 is connected between the antenna 101 and the receiver 107. To match the impedance.
The control circuit 110 acquires the applied voltage value VD1 of the varactor diode that optimizes impedance matching between the antenna 101 and the receiver 107 from the logic circuit 108, acquires communication channel information from the memory 111, and acquires the acquired VD1 Using the communication channel information and fr which is the difference between the resonant frequencies of the transmitting and receiving antennas, the optimum matching circuit is selected from the matching circuits 103a to 103e, and a switching instruction indicating the selected matching circuit is output to the changeover switch 104. Thus, impedance matching between the antenna 101 and the transmission circuit 105 is discretely taken.

As an example, the control circuit 110 holds in advance a frequency shift amount table shown in FIG. 3, a communication channel information table shown in FIG. 4, and a matching circuit selection table shown in FIG.
The frequency shift amount table indicates that the reception frequency is determined by the impedance change between the reception circuit 107 and the antenna 101 when the applied voltage value VD1 output by the logic circuit 108 to the D / A converter 109 and VD1 are given. Is data that has been measured in advance and indicates the correspondence with the frequency shift amount f1 that indicates how much is shifted.

The communication channel information table is data indicating the communication channel (CH), the frequency range corresponding to the communication channel, and the difference between the reception frequency and the transmission frequency in the communication channel.
For example, when the communication channel is 1CH, the frequency range used for communication is 1940 MHz to 1950 MHz, and the difference between the reception frequency and the transmission frequency is 40 MHz.

The matching circuit selection table is data indicating the shift amount of the transmission frequency and the number SW of the matching circuit to be used that is a matching circuit to be selected to shift the shift amount.
For example, when the shift amount of the transmission frequency is calculated to be 10 MHz, the control circuit outputs 1 as SW to the changeover switch 104.
Hereinafter, processing until the control circuit 110 selects one of the matching circuits 103a to 103e will be described.

The control circuit 110 reads the channel number CH currently used for communication from the memory 111 and acquires the value of VD1 from the logic circuit 108.
Next, the control circuit 110 reads the frequency shift amount f1 corresponding to the acquired VD1 from the frequency shift amount table.
Next, the control circuit 108 reads the frequency difference fr corresponding to the read CH.

The control circuit 108 calculates the transmission frequency f2 to be shifted by the following equation.
f2 = f1-fr
The control circuit 108 selects the SW corresponding to f2 from the matching circuit selection table and outputs it to the changeover switch 104.
<Operation>
The operation of the mobile phone 1 will be described separately for the reception operation and the transmission operation with reference to the drawings.
(Reception operation)
When the antenna 101 receives a signal (step S101), the received signal passes through the duplexer 102 and the matching circuit 106 and reaches the receiving circuit 107.

The receiving circuit 107 measures the RSSI of the received signal and outputs the RSSI value to the logic circuit 108 (step S102).
The logic circuit 108 acquires and stores the RSSI value, and increases the voltage value VD1 output to the D / A converter 109 by the voltage value dV (step S103).
The initial value of VD1 is zero.

The D / A converter 109 applies a voltage corresponding to VD1 increased by dV in step S103 to the matching circuit 106. The capacitance of matching circuit 106 is changed by increasing VV1 by dV in step S103, and the impedance between antenna 101 and receiver 107 is changed by the change in capacitance (step S104).
The receiving circuit 107 measures the RSSI of the received signal at predetermined time intervals, and outputs the RSSI value to the logic circuit 108.

The logic circuit 108 acquires the RSSI value from the reception circuit 107, and determines whether the RSSI has improved compared to the previously acquired RSSI value, that is, whether the RSSI value has decreased (step S106).
When there is no change in RSSI (step S106: no change), that is, the RSSI value acquired last time matches the RSSI value acquired this time, or the difference between the RSSI value acquired last time and the RSSI value acquired this time is less than a predetermined value. When the change amount is small, the logic circuit 108 outputs the voltage value VD1 currently output to the D / A converter 109 to the control circuit 110 (step S110).

The matching circuit 106 writes communication channel information indicating the current communication channel in the memory 111 (step S111), and ends the process.
If it is determined in step S106 that the RSSI has improved (step S106: improvement), that is, if the RSSI value acquired this time is smaller than the RSSI value acquired last time, the logic circuit 108 further Then, it is determined whether or not dV has been increased (step S120). If it has been increased (step S120: YES), dV is further increased (step S121), and the process proceeds to step S104.

In step S120, if dV is not increased, that is, if it is decreased (step S120: NO), dV is further decreased (step S131), and the process proceeds to step S104.
If it is determined in step S106 that the RSSI has deteriorated (step S106: deteriorated), that is, if the RSSI value acquired this time is larger than the RSSI value acquired last time, the logic circuit 108 further sets dV for the previous time. It is determined whether or not it has been increased (step S130). If it has been increased (step S130: YES), dV is decreased (step S131), and the process proceeds to step S104.

In step S130, when it is determined that it has not been increased, that is, has been decreased (step S130: NO), dV is increased (step S121), and the process proceeds to step S104.
Through the above processing, the impedance between the antenna 101 and the receiving circuit 107 is matched, and the applied voltage VD1 to the varactor diode converges.
(Transmission operation)
The transmission operation will be described with reference to the flowchart shown in FIG.

The transmission circuit 105 outputs a signal to be transmitted, and the output signal passes through the change-over switch 104, passes through one of the selected matching circuits 103a to 103e and the shared device 102, and enters the air from the antenna 101. Released.
The control circuit 110 reads the information on the currently used communication channel (used communication channel information) written in the memory 111 by the matching circuit 106 (step S201).

The control circuit 110 acquires VD1 output from the logic circuit 110 to the D / A converter 109 from the logic circuit 110 (step S202).
The control circuit 110 reads the difference fr between the transmission frequency and the reception frequency corresponding to the communication channel indicated by the acquired used communication channel information from the communication channel information table (step S203).

Next, the control circuit 110 reads the received frequency shift amount f1 corresponding to the acquired VD1 from the frequency shift amount table (step S204).
The control circuit 110 sets the transmission frequency shift amount f2 to the following equation: f2 = f1−fr
(Step S205), the SW corresponding to the calculated f2 is selected from the matching circuit selection table and output to the changeover switch 104.

The changeover switch 104 puts the switch indicated by SW into a connected state (step S206).
Next, the control circuit 110 reads communication channel information from the memory 111 (step S207), and determines whether or not the channel is the same as the communication channel information read last time (step S208).

When there is a change in the communication channel information (step S208: YES), the process proceeds to step S202. When there is no change (step S208: NO), VD1 is acquired from the logic circuit 108 (step S209).
It is determined whether or not the acquired VD1 is the same as the previously acquired VD1 (step S210). If there is a change (step S210: YES), the process proceeds to step S204, and if there is no change (step S210). : NO), the process is terminated.

The mobile phone 1 repeatedly executes the above-described transmission operation and reception operation in parallel.
<Modification>
Needless to say, the present invention is not limited to the above-described embodiment. The following cases are also included in the present invention.
(1) A MEMS (Micro Electro Mechanical Systems) switch may be used as the changeover switch of the present embodiment.

As a result, power loss and the like in switching the matching circuit can be reduced.
(2) In this embodiment, a varactor diode is used to change the impedance value of the matching circuit of the receiving circuit. However, the present invention is not limited to this, and the impedance value can be adjusted by external control. Other circuit configurations may be used.
(3) In this embodiment, the example of using the matching circuits 103a to 103e as the matching circuit of the transmitter has been described as an example. However, the present invention is not limited to this, and two or more matching circuits are possible. Needless to say.

  (4) In the present embodiment, the control circuit 110 acquires the voltage applied to the matching circuit 106 and selects one of the matching circuits 103a to 103e using the voltage value. However, the present invention is not limited to this. Instead, the capacitance value of the varactor diode may be used instead of the voltage value. In this case, the change amount of the resonance frequency corresponding to the capacitance value of the varactor diode may be stored in the control circuit 110.

(5) In the present embodiment, the matching circuit 106 is configured by a varactor diode. However, the present invention is not limited to this, and linear elements 402a to 402e are replaced by a changeover switch 401 as shown in FIG. It is good also as a structure switched and used.
(6) In this embodiment, an example using one varactor diode has been described. However, the present invention is not limited to this, and a plurality of varactor diodes may be connected in series, or a plurality of varactor diodes may be connected in parallel. You may connect to.

Moreover, you may combine with at least 1 varactor diode and the other device which can adjust an impedance value with the control signal from the outside.
(7) In this embodiment, the case where one antenna is used has been described as an example. However, the present invention is not limited to this, and two or more antennas may be used as shown in FIG. .
In this case, the antenna changeover switch 503 provided in place of the duplexer 102 selects either the antenna 501 or the antenna 502 as two antennas, and the reception of the selected antenna described in <Operation> above. It is necessary to perform an operation and a transmission operation.

  (8) In this embodiment, the logic circuit 108 changes the applied voltage VD1 of the varactor diode so that the RSSI level output from the receiving circuit 107 is maximized. However, the present invention is not limited to this. . For example, as shown in FIG. 10, the directional coupler 601, the comparator 602, and the applied voltage control circuit 603 are configured, and the directional coupler 601 outputs (a) the duplexer 102 to the directional coupler 601. The difference between the two signal levels of the signal proportional to the signal level and (b) the signal proportional to the signal level from the matching circuit 106 to the directional coupler 601 is increased, that is, from the matching circuit 106 to the directional coupler 601. The control circuit 603 may control the voltage VD1 applied to the matching circuit 106 so as to reduce the reflected wave.

(9) In the present embodiment, a matching circuit is provided that evenly distributes the voltage applied to the varactor diodes and obtains an impedance value corresponding to each voltage section. However, the present invention is not limited to this. The voltage may be distributed unevenly.
(10) The transmission operation and the reception operation described in <Operation> of the present embodiment may be repeatedly executed at a preset time interval, or when there is a fluctuation in the VD1 that is greater than or equal to a preset threshold value. Alternatively, it may be performed when the RSSI measured in the receiving circuit 107 fluctuates by a predetermined threshold value or more.

(11) In the present embodiment, the matching circuit of the transmission unit has a single-stage configuration, but the present invention is not limited to this and may have a multi-stage configuration. For example, as shown in FIG. 11, a multi-stage configuration may be employed in which a plurality of matching circuits 702a to 702o are provided via antenna changeover switches 701a to 701e at the subsequent stage of the matching circuits 103a to 103e.
By providing the matching circuits 702a to 702o, the impedance between the antenna 101 and the transmission circuit 105 can be matched with higher accuracy.

(12) In the present embodiment, the matching circuit 103 of the transmission unit is switched by the antenna changeover switch 104. However, the present invention is not limited to this, and a matching circuit 903 using a PIN diode 901 as shown in FIG. It may be possible to switch the availability of.
If the PIN diode 901 is controlled to be disconnected, the matching circuit 902 is used alone. If the PIN diode 901 is controlled to be conductive, the matching circuit 902 and the matching circuit 903 are used. The impedance between the transmission circuit 105 and the antenna 101 is matched.

(13) Examples of the antenna 103 of the wireless device according to the present embodiment include a helical antenna, a whip antenna, an inverted F antenna, a chip antenna, and a meander line. However, the present invention is not limited to this, and any antenna can be configured. It is.
(14) Specifically, each of the above devices is a computer system including a microprocessor, a ROM, a RAM, a hard disk unit, a display unit, a keyboard, a mouse, and the like. A computer program is stored in the RAM or the hard disk unit. Each device achieves its function by the microprocessor operating according to the computer program. Here, the computer program is configured by combining a plurality of instruction codes indicating instructions for the computer in order to achieve a predetermined function.

  (15) A part or all of the constituent elements constituting each of the above devices may be configured by one system LSI (Large Scale Integration). The system LSI is a super multifunctional LSI manufactured by integrating a plurality of components on one chip, and specifically, a computer system including a microprocessor, a ROM, a RAM, and the like. . A computer program is stored in the RAM. The system LSI achieves its functions by the microprocessor operating according to the computer program. These may be individually made into one chip, or may be made into one chip so as to include a part or all of them.

The name used here is LSI, but it may also be called IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.
Further, the method of circuit integration is not limited to LSI, and implementation with a dedicated circuit or a general-purpose processor is also possible. An FPGA (Field Programmable Gate Array) that can be programmed after manufacturing the LSI or a reconfigurable processor that can reconfigure the connection and setting of circuit cells inside the LSI may be used.

Further, if integrated circuit technology comes out to replace LSI's as a result of the advancement of semiconductor technology or a derivative other technology, it is naturally also possible to carry out function block integration using this technology. Biotechnology can be applied.
(16) A part or all of the components constituting each of the above devices may be configured as an IC card or a single module that can be attached to and detached from each device. The IC card or the module is a computer system including a microprocessor, a ROM, a RAM, and the like. The IC card or the module may include the super multifunctional LSI described above. The IC card or the module achieves its function by the microprocessor operating according to the computer program. This IC card or this module may have tamper resistance.

(17) The present invention may be the method described above. Further, the present invention may be a computer program that realizes these methods by a computer, or may be a digital signal composed of the computer program.
The present invention also provides a computer-readable recording medium such as a flexible disk, hard disk, CD-ROM, MO, DVD, DVD-ROM, DVD-RAM, BD (Blu-ray Disc). ), Recorded in a semiconductor memory or the like. Further, the present invention may be the computer program or the digital signal recorded on these recording media.

Further, the present invention may transmit the computer program or the digital signal via an electric communication line, a wireless or wired communication line, a network represented by the Internet, a data broadcast, or the like.
The present invention may be a computer system including a microprocessor and a memory, wherein the memory stores the computer program, and the microprocessor operates according to the computer program.

In addition, the program or the digital signal is recorded on the recording medium and transferred, or the program or the digital signal is transferred via the network or the like, and is executed by another independent computer system. It is good.
(18) The above embodiment and the above modifications may be combined.

The present invention is used as a wireless communication terminal such as a cellular phone in which proximity of a human body affects communication, and is implemented by a manufacturer that manufactures and sells a wireless communication terminal.

It is a block diagram of the mobile telephone in one Embodiment of this invention. It is a figure which shows the frequency characteristic of the antenna of one Embodiment of this invention. It is a figure which shows an example of the frequency shift amount table which a control circuit hold | maintains. It is a figure which shows an example of the communication channel information table which a control circuit hold | maintains. It is a figure which shows an example of the matching circuit selection table which a control circuit hold | maintains. It is a flowchart which shows reception operation | movement. It is a flowchart which shows transmission operation | movement. It is a block diagram of the mobile phone which concerns on a modification. It is a block diagram of the mobile phone which concerns on a modification. It is a block diagram of the mobile phone which concerns on a modification. It is a block diagram of the mobile phone which concerns on a modification. It is a block diagram of the mobile phone which concerns on a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Antenna 102 Duplexer 103a-e Matching circuit 104 Changeover switch 105 Transmission circuit 106 Matching circuit 107 Reception circuit 108 Logic circuit 109 D / A converter 110 Control circuit 111 Memory 112 Transmission part 113 Reception part 301 The frequency characteristic of the antenna in an ideal state 302 Frequency characteristics of antenna in actual use (no adjustment)
302 Frequency characteristics of antenna in actual use (after adjustment)
401 changeover switch 402 matching circuit 501 antenna 502 antenna 503 antenna changeover switch 601 directional coupler 602 comparator 603 applied voltage control circuit 701a to e changeover switch 702a to o matching circuit 703 transmitter 901 PIN diode 902 matching circuit 903 matching circuit

Claims (13)

A portable wireless terminal including a transmitting unit and a receiving unit that share the same antenna and transmit and receive based on a communication specification that defines a specified transmission frequency and a specified reception frequency,
The receiver is
Including a reception matching circuit connected to the antenna and having variable impedance, changing the impedance to maximize the power intensity of the signal received by the antenna, and outputting a parameter determined by the changed impedance;
The transmitter is
A transmission matching circuit connected to the antenna and having a variable impedance;
The parameter is acquired, and based on the acquired parameter, the amount of change of the resonance frequency from the specified reception frequency due to the impedance change of the reception matching circuit is estimated, and from the amount of change, the specified reception frequency and the specified transmission frequency A control circuit for calculating a necessary change amount of the resonance frequency from the specified transmission frequency by reducing the difference between
And a change circuit that changes the impedance of the transmission matching circuit in accordance with the required change amount. The transmission matching circuit includes a plurality of transmission matching elements each having a different impedance, and each transmission matching element is selectively connected to the antenna;
The portable radio terminal according to claim 1, wherein the change circuit connects a transmission matching element having an impedance corresponding to the required change amount to the antenna. The control circuit includes:
In advance, a plurality of voltage values and the amount of change in the resonance frequency when the voltage indicated by each voltage value is applied to the reception matching circuit are stored in association with each other.
Stores the specified reception frequency and specified transmission frequency based on the communication specifications,
A storage circuit that stores a change amount of a resonance frequency that changes when each transmission matching element is connected to the antenna;
An acquisition circuit for acquiring a voltage value as the parameter from the receiver;
The amount of change in the resonance frequency from the specified transmission frequency is read by reading the amount of change in the resonance frequency corresponding to the acquired voltage value and subtracting the difference between the specified reception frequency and the specified transmission frequency from the read amount of change. A calculation circuit for calculating
A selection circuit that selects a transmission matching element having an impedance corresponding to the required change amount, and
The portable radio terminal according to claim 2, wherein the change circuit connects a selected transmission matching element to the antenna. The transmission unit and the reception unit perform wireless communication with other devices using a plurality of communication channels,
Each communication channel is assigned a specified transmission frequency and specified reception frequency different from other communication channels based on the communication specifications,
The storage circuit for each communication channel
In advance, a plurality of voltage values and the amount of change in the resonance frequency when the voltage indicated by each voltage value is applied to the reception matching circuit are stored in association with each other.
Stores the specified reception frequency and specified transmission frequency based on the communication specifications,
Storing the amount of change in resonant frequency that changes when each transmit matching element is connected to the antenna;
The calculation circuit reads the amount of change in the resonance frequency corresponding to the acquired voltage value for the communication channel being used, and subtracts the difference between the specified reception frequency and the specified transmission frequency from the read amount of change. The portable wireless terminal according to claim 3, wherein a necessary change amount of the resonance frequency from the prescribed transmission frequency is calculated. The reception matching circuit is a variable capacitance element,
The parameter is a voltage value of a voltage applied to the reception matching circuit,
The portable radio terminal according to claim 1, wherein the control circuit acquires the voltage value as the parameter. The mobile wireless terminal according to claim 2, wherein each of the plurality of transmission matching elements is a linear element. Each of the plurality of transmission matching elements
3. The portable radio according to claim 2, having an inductance value corresponding to a small section obtained by dividing a voltage section from a lower limit to an upper limit of a voltage that can be applied to the reception matching circuit into the same number as the number of transmission matching elements. Terminal. Each of the plurality of transmission matching elements
The average impedance value corresponding to a small section obtained by dividing a voltage section from a lower limit to an upper limit of a voltage that can be applied to the reception matching circuit into the same number as the number of transmission matching elements. Mobile wireless terminals. The portable radio terminal according to claim 1, wherein the reception matching circuit is a linear element. The receiver is
A directional coupler for acquiring a direct wave of a signal received by the antenna and a reflected wave generated in the receiving unit;
A comparator for comparing the direct wave and the reflected wave;
The portable wireless terminal according to claim 1, wherein the impedance is changed to maximize a difference between the direct wave and the reflected wave, and a parameter for determining the changed impedance is output. An impedance matching method used for a portable wireless terminal including a transmission unit and a reception unit that shares the same antenna and transmits and receives based on a communication specification that defines a specified transmission frequency and a specified reception frequency,
The receiving unit includes a reception matching circuit connected to the antenna and having a variable impedance,
The transmission unit includes a transmission matching circuit connected to the antenna and having a variable impedance,
The impedance matching method is:
An output step of changing the impedance of the reception matching circuit to maximize the power intensity of the signal received by the antenna and outputting a parameter determined by the changed impedance;
The parameter is acquired, and based on the acquired parameter, the amount of change of the resonance frequency from the specified reception frequency due to the impedance change of the reception matching circuit is estimated, and from the amount of change, the specified reception frequency and the specified transmission frequency A control step for calculating a necessary change amount of the resonance frequency from the specified transmission frequency by reducing the difference between
A change step of changing an impedance of the transmission matching circuit in accordance with the required change amount. A computer program used for a portable wireless terminal including a transmitter and a receiver, which shares the same antenna and transmits and receives based on a communication specification that defines a specified transmission frequency and a specified reception frequency,
The receiving unit includes a reception matching circuit connected to the antenna and having a variable impedance,
The transmission unit includes a transmission matching circuit connected to the antenna and having a variable impedance,
The computer program is
An output step of changing the impedance of the reception matching circuit to maximize the power intensity of the signal received by the antenna and outputting a parameter determined by the changed impedance;
The parameter is acquired, and based on the acquired parameter, the amount of change in the resonance frequency from the specified reception frequency due to the impedance change of the reception matching circuit is estimated, and from the change, the specified reception frequency and the specification based on the communication specifications are estimated. A control step of calculating a necessary change amount of the resonance frequency from the specified transmission frequency by reducing a difference with the transmission frequency;
And a changing step of changing an impedance of the transmission matching circuit in accordance with the required change amount. An integrated circuit including a transmitter and a receiver that share the same antenna and transmit and receive based on a communication specification that defines a prescribed transmission frequency and a prescribed reception frequency,
The receiver is
Including a reception matching circuit connected to the antenna and having a variable impedance, changing the impedance to maximize a power intensity of a signal received by the antenna, and outputting a parameter that determines the changed impedance;
The transmitter is
A transmission matching circuit connected to the antenna and having a variable impedance;
The parameter is acquired, and based on the acquired parameter, the amount of change of the resonance frequency from the specified reception frequency due to the impedance change of the reception matching circuit is estimated, and from the amount of change, the specified reception frequency and the specified transmission frequency A control circuit for calculating a necessary change amount of the resonance frequency from the specified transmission frequency by reducing the difference between
And a change circuit that changes the impedance of the transmission matching circuit in accordance with the required change amount.

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