JP2002232304A - Impedance matching device - Google Patents

Abstract

(57) Abstract: An impedance matching device for impedance matching between a transmission signal generation circuit of a transmitter and an antenna, and reduces the load on switching of a relay for changing the reactance of a variable element included in the matching circuit. . A matching circuit is provided between a transmission signal generation circuit of a transmitter and an antenna, and the reactance of variable elements of the matching circuit is changed by switching a relay to transmit a transmission signal. When impedance matching between the generating circuit 7 and the antenna 8 is performed,
When the transmission signal from the transmission signal generation circuit 7 is off, the relay is switched to change the reactances of the variable elements X1 to X3 to match the impedance between the transmission signal generation circuit 7 and the antenna 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impedance matching device for impedance matching between a transmission signal generation circuit of a transmitter and an antenna, and more particularly to switching of a relay for changing the reactance of a variable element included in the matching circuit. The present invention relates to an impedance matching device with reduced burden.

[0002]

2. Description of the Related Art For example, when power is supplied from a circuit on a power supply side to a circuit on a load side in a communication device or the like, a matching circuit is inserted into a connection point between these two circuits to match impedances on the power supply side and the load side. Let it be done. When the impedances are matched in this way, there is no loss due to power reflection at the connection point between the two circuits, and the maximum power can be supplied to the load side.

FIG. 3 shows an example of a circuit configuration of a digital impedance matching device provided with such a matching circuit 16. The digital impedance matching device shown in the figure includes an impedance error detector (DISC) 11 and A
It comprises an / D (analog-digital) converter 12, a comparator (voltage comparator) 13, an MPU (microprocessor unit) 14, a variable element switching drive circuit 15, and a matching circuit 16, for example. It is provided between an input-side transmission signal generating circuit 17 having an impedance Z1 and an output-side antenna 18 having an impedance Z2. Note that, for example, the impedances Z1 and Z2 expressed in the form of complex impedances can generally change according to the frequency of a signal to be processed.

[0004] In the example shown in FIG.
Is composed of three variable elements (matching variable elements) Y1 to Y3. Specifically, one end of the matching variable element Y1 is connected to the input terminal of the matching circuit 16, and the other end of the matching variable element Y1 is connected to one end of the matching variable element Y3. The other end of the variable element for use Y3 is connected to the output terminal of the matching circuit 16. A matching variable element Y2 is connected to a connection point of these two matching variable elements Y1 and Y3.
Is connected, and the other end of the matching variable element Y2 is grounded.

Here, each of the matching variable elements Y1 to Y3 uses a group of capacitors and a group of coils that can switch the reactance to a plurality of discrete values stepwise in binary steps, for example, by switching relays. It is configured.

As an example, FIG. 4A shows a configuration example of a matching variable element formed by using n capacitors C1 to Cn and n relays K1 to Kn. Here, n is plural. In this matching variable element, one end of each of n relays K1 to Kn is connected in parallel to an input terminal, and the other end of each relay K1 to Kn is connected to one end of each of capacitors C1 to Cn. The other ends of the n capacitors C1 to Cn are connected to output terminals.
In such a matching variable element, the capacitance of the capacitor as the entire matching variable element can be variably switched in a binary step in accordance with the open / close switching state of each of the relays K1 to Kn. Are variably switched in binary steps.

[0007] As another example, FIG.
2 shows an example of the configuration of a matching variable element formed by using coils L1 to Lm and m relays S1 to Sm.
Here, m is plural. In this matching variable element, m coils L1 to Lm are connected in series between an input terminal and an output terminal, and relays S1 to Sm are connected between both ends of each coil L1 to Lm. I have. In such a matching variable element, the inductance of the coil as the entire matching variable element can be variably switched in a binary step according to the open / close switching state of each of the relays S1 to Sm. Are variably switched in binary steps.

Next, an example of the matching operation performed by the digital impedance matching device shown in FIG. 3 will be described.
In the digital impedance matching device shown in the figure, when the transmission signal generated by the transmission signal generation circuit 17 is input to the impedance error detector 11 and then output to the antenna 18 through the matching circuit 16, the following In this way, the impedance of the transmission signal generation circuit 17 on the input side is matched with that of the antenna 18 on the output side.

That is, the impedance error detector 11
Are converted into digital signals by the A / D converter 12 and the comparator 13 and input to the MPU 14, and each matching is performed by the MPU 14 via the variable element switching drive circuit 15 based on the input digital signal. By adjusting the reactances of the variable elements Y1 to Y3, the impedance of the entire matching circuit 16 is adjusted,
Thus, the input side and the output side are impedance-matched.

Specifically, the impedance error detector 1
1 detects an impedance error between the input-side impedance Z1 and the output-side impedance Z2 by separating it into, for example, a resistance component (R) and a phase component (φ), and digitally detects the detected impedance error via a comparator 13. The signal is converted to a signal and output to the MPU 14.

The MPU 14 is arranged to increase or decrease the reactance of each of the matching variable elements Y1 to Y3 to make the resistance component or the phase component of the impedance error zero or close to zero based on the digital signal inputted from the comparator 13. Control signal e, control signal f, and control signal g for performing control in the determined reactance increase / decrease direction.
Is output to the switching drive circuit 15 of the variable element.

The switching drive circuit 15 for the variable element includes the MPU 1
Control signal e, control signal f, control signal g
A signal e ′ for switching and driving a relay (variable element switching relay) provided in each of the matching variable elements Y1 to Y3,
The signal f 'and the signal g' are converted and output, whereby the reactance of each of the matching variable elements Y1 to Y3 is changed in a binary step to realize impedance matching between the input side and the output side. It should be noted that the signal lines from the variable element switching drive circuit 15 to the respective matching variable elements Y1 to Y3 are indicated by dotted lines in FIG.

As an example of a conventional technique for performing impedance matching, in an automatic antenna tuner described in Japanese Patent Publication No. 6-46712, an impedance matching between an output unit (transmission signal generating circuit) of a transmitter and an antenna is performed. In the meantime, it is possible to determine the band from the frequency of the transmission wave input to the antenna and to perform tap switching corresponding to the band to the matching coil, or to execute the tap switching when the carrier of the transmission wave is detected. In the case where no tap is detected, the tap switching is not executed and the state of the already set tap is maintained.

[0014]

However, in the conventional impedance matching device shown in FIG. 3, for example, the impedance error detecting circuit 11 detects the impedance error by separating it into a resistance component and a phase component. The impedance error detector 1
It is necessary to apply a high-frequency power transmission signal from the input side of the input device 1. For this reason, the variable element switching relays of the matching variable elements Y1 to Y3 are switched in a state where the high-frequency power is applied.

In such a conventional impedance matching device, it is necessary to use a relay capable of withstanding hot switching for performing relay switching in a state where high-frequency power is applied as a variable element switching relay. A relay having a large contact rating is required, and as a result, a special and expensive relay is required.

The present invention has been made to solve such a conventional problem. When impedance matching is performed between a transmission signal generation circuit of a transmitter and an antenna, the reactance of a variable element included in the matching circuit is changed. The load on switching the relays for
Thus, an object of the present invention is to provide an impedance matching device that enables a general-purpose, low-cost relay to be used as a variable element switching relay, for example.

[0017]

In order to achieve the above object, an impedance matching device according to the present invention includes a matching circuit provided between a transmission signal generation circuit of a transmitter and an antenna, and the matching circuit has When the impedance of the transmission signal generation circuit and the antenna is matched by changing the reactance of the variable element by switching the relay, the matching means switches the relay when the transmission signal from the transmission signal generation circuit is off, and reacts the variable element. Is changed so that the transmission signal generation circuit and the antenna are impedance-matched.

Therefore, when impedance matching is performed between the transmission signal generation circuit of the transmitter and the antenna, it is possible to reduce the burden of switching the relay for changing the reactance of the variable element included in the matching circuit. For example, a general-purpose, low-cost relay can be used as a variable element switching relay.

Here, as the transmitter, for example, various transmitters provided in a wireless communication device may be used. Further, as the transmission signal generation circuit, for example, various transmission signal generation circuits that generate wireless transmission signals may be used.
Also, various antennas may be used. Also, circuits having various configurations may be used as the matching circuit. The variable element can be configured using, for example, a coil, a capacitor, or both.

As the transmission signal, it is preferable to apply the present invention to a transmitter that generates a high-frequency power transmission signal by a transmission signal generation circuit and wirelessly transmits the signal by an antenna. It is also possible to apply the present invention. As an example of switching the relay when the transmission signal is off, as an example, a mode in which the on / off state of the transmission signal is determined and the relay is switched when the transmission signal is off can be used. As an example, it is also possible to use a mode in which the transmission signal is controlled to be turned off when the relay is switched.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A digital impedance matching device according to one embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a circuit configuration example of a digital impedance matching device of the present example to which the impedance matching device according to the present invention is applied. As shown in the figure, the digital impedance matching device of the present example comprises an impedance error detector 1, an A / D converter 2, a comparator 3, an MPU 4
And a variable element switching drive circuit 5 and a matching circuit 6. The digital impedance matching device of the present example is provided, for example, between the input-side transmission signal generation circuit 7 having the impedance Z1 and the output-side antenna 8 having the impedance Z2. The antenna 8 is provided in a transmitter of a communication device to which the present invention is applied.

Further, as shown in FIG.
Is composed of three variable elements (matching variable elements) X1 to X3. Specifically, one end of the matching variable element X1 is connected to the input end of the matching circuit 6, and the other end of the matching variable element X1 is connected to one end of the matching variable element X3. The other end of the variable element X3 is a matching circuit 6
Connected to the output end of the Further, one end of the matching variable element X2 is connected to a connection point of the two matching variable elements X1 and X3, and the other end of the matching variable element X2 is grounded. Further, each matching variable element X1 to X3
Can be configured using a circuit as shown in, for example, FIGS. 4A and 4B.

Next, an example of the matching operation performed by the digital impedance matching device of this embodiment will be described. Note that the matching operation performed by the digital impedance matching device of the present example is, for example, as described above, except that the MPU 4 controls the transmission signal generation circuit 7 to turn off the transmission signal when switching the variable element switching relay. This is the same as the matching operation performed by the digital impedance matching device shown in FIG.

Specifically, in the digital impedance matching device of this embodiment, the transmission signal generated by the transmission signal generation circuit 7 is input to the impedance error detector 1 and then output to the antenna 8 through the matching circuit 6. At this time, the impedance of the transmission signal generating circuit 7 on the input side and the antenna 8 on the output side are matched as follows.

That is, each element detected by the impedance error detector 1 is digitized by the A / D converter 2 and the comparator 3 and input to the MPU 4, and the variable element is set based on the digital signal input to the MPU 4. Of each matching variable element X1 through the switching drive circuit 5
The impedance of the entire matching circuit 6 is adjusted by adjusting the reactance of X3, and thereby the input side and the output side are impedance-matched. Also, MP
U4 controls the transmission signal generation circuit 7 to switch off the transmission signal when switching the relays provided in each of the matching variable elements X1 to X3.

Specifically, the impedance error detector 1
Detects an impedance error between an input-side impedance Z1 and an output-side impedance Z2, for example, by separating it into a resistance component (R) and a phase component (φ), and detects the detected impedance error via a comparator 3 as a digital signal. And outputs it to MPU4.

The MPU 4 is configured to increase or decrease the reactance of each of the matching variable elements X1 to X3 to make the resistance component or the phase component of the impedance error zero or close to zero based on the digital signal input from the comparator 3. And outputs a control signal a, a control signal b, and a control signal c for controlling the determined reactance increasing / decreasing direction to the switching drive circuit 5 of the variable element.

When the MPU 4 outputs the control signals a, b, and c as described above to the variable element switching drive circuit 5, the MPU 4 synchronizes the control signals a, b, and c with the transmission signal generation circuit. A transmission on / off signal d for switching on / off the output of the transmission signal from the transmission signal generator 7 is output to the transmission signal generation circuit 7.

The variable element switching drive circuit 5 converts the control signal a, control signal b, and control signal c input from the MPU 4 to the relays (variable element switching relays) provided in the respective matching variable elements X1 to X3. A signal a ', a signal b', and a signal c 'for switching driving are converted and output, whereby the reactance of each of the matching variable elements X1 to X3 is changed in a binary step, and the impedance between the input side and the output side is changed. Achieve alignment. In FIG. 1, the variable element switching drive circuit 5
Therefore, the signal lines to the matching variable elements X1 to X3 are indicated by dotted lines for easy viewing.

FIG. 2A shows an example of the output timing of the control signals a, b and c output from the MPU 4 for switching the variable element switching relay, and FIG. Transmission on / off signal d output from MPU 4 to turn on / off the transmission signal from
(B) shows an example of the output timing, and an example of the relationship between these two output timings is shown. Note that the horizontal axes in FIGS. 7A and 7B indicate time, and the vertical axes indicate signal levels.

As shown in FIGS. 3A and 3B, in this example, when the transmission signal from the transmission signal generating circuit 7 is off, the control signals a, b, c which are turned off or on. When the variable element switching relays of the respective matching variable elements X1 to X3 are opened and closed according to the control signals a, b, and c that are turned off or on, the transmission signal is turned off. This guarantees that no high-frequency power is applied to the contacts of the variable element switching relay. In this example, for convenience of explanation, the control signals a, b, and c have been described as being off or on signals.
Various signals may be used as b and c, and similarly, various signals may be used as the transmission on / off signal d and the like.

As described above, in the digital impedance matching device of the present embodiment, when the variable element switching relay is switched, the transmission signal generation circuit 7 is synchronized with the control signals a, b, and c for performing the switching. To turn off the application of the transmission signal of the high-frequency power to the matching circuit 6.

Therefore, in the digital impedance matching device of this embodiment, the transmission signal generation circuit 7 of the transmitter and the antenna 8
When impedance matching is performed, it is possible to reduce the burden of switching the relays for changing the reactances of the matching variable elements X1 to X3 included in the matching circuit 6, whereby, for example, a general-purpose low-cost relay Can be used as a variable element switching relay.

Specifically, in the digital impedance matching device of the present embodiment, a cold switching type relay that performs relay switching in a state where high frequency power is not applied to the relay contact can be used as a variable element switching relay. Accordingly, since a general-purpose relay can be used, the selection range of the relay can be expanded, and as a result, a low-cost relay can be used.

In this embodiment, when the transmission signal from the transmission signal generating circuit 7 is off (in a state where it is not output) under the control of the MPU 4, the variable element switching relay is switched to change the matching variable elements X1 to X3. The function of matching the impedance of the transmission signal generation circuit 7 and the antenna 8 by changing the reactance of the transmission signal generating circuit 7 constitutes the matching means according to the present invention.

In this embodiment, the matching variable elements X1 to X1
Control was performed such that the transmission signal from the transmission signal generation circuit 7 was turned off when switching the variable element switching relay for changing the reactance of X3. It is also possible to use a configuration in which the transmission signal is monitored and the variable element switching relay is switched when the transmission signal is off. That is, in this example, the transmission signal is turned off in synchronization with the control signals a, b, and c for switching the variable element switching relay. However, as another configuration, the variable element switching relay is synchronized with the transmission signal. It is also possible to use a configuration that outputs a control signal for switching the mode.

Here, the configuration of the impedance matching device according to the present invention is not necessarily limited to the configuration described above, and various configurations may be used. Further, the application field of the present invention is not necessarily limited to the above-described fields, and the present invention can be applied to various fields. As an example, the present invention provides an impedance matching device for impedance matching between a transmission signal generation circuit of a transmitter and an antenna. However, a matching circuit of an impedance matching device having a similar configuration can be provided with an arbitrary circuit on the input side and an output. It is also possible to provide between any two circuits on the side to match the impedance of these two circuits.

Various processes performed in the impedance matching device according to the present invention are controlled, for example, by the processor executing a control program stored in the ROM on hardware resources including a processor and a memory. A configuration may be used, and
For example, each functional means for executing the processing may be configured as an independent hardware circuit. Further, the present invention can be understood as a computer-readable recording medium such as a floppy (registered trademark) disk or a CD-ROM storing the above-mentioned control program or the program (the program itself). By inputting the information to a computer and causing the processor to execute the processing, the processing according to the present invention can be performed.

[0039]

As described above, according to the impedance matching device of the present invention, a matching circuit is provided between a transmission signal generating circuit of a transmitter and an antenna, and the reactance of a variable element included in the matching circuit is provided. When the transmission signal from the transmission signal generating circuit is turned off, the relay is switched to change the reactance of the variable element to change the reactance of the variable element. Since the circuit and the antenna are impedance-matched, it is possible to reduce the burden of switching the relay for changing the reactance of the variable element included in the matching circuit. It can be used as a variable element switching relay.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a circuit configuration example of a digital impedance matching device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a relationship between output timings of a variable element variable control signal and a transmission on / off signal.

FIG. 3 is a diagram illustrating a circuit configuration example of a digital impedance matching device according to a conventional example.

FIG. 4 is a diagram illustrating a configuration example of a matching variable element whose reactance can be switched in a binary step.

[Explanation of symbols]

1. Impedance error detector (DISC) 2.
・ A / D converter, 3 ・ ・ Comparator, 4 ・ ・ MPU
(Microprocessor unit) 5, a variable element switching drive circuit, 6. a matching circuit, 7, a transmission signal generating circuit, 8, an antenna, X1 to X3, a variable element for matching, K1 to Kn, S1 ~ Sm..Relay, C1 ~ Cn
..Capacitors, L1 to Lm coils

Claims (1)

[Claims] A matching circuit is provided between a transmission signal generation circuit of a transmitter and an antenna, and the transmission signal generation circuit and the antenna are changed by changing the reactance of a variable element of the matching circuit by switching a relay. An impedance matching device for performing impedance matching, comprising: matching means for changing a reactance of a variable element by switching a relay when a transmission signal from a transmission signal generation circuit is off to change impedance of the transmission signal generation circuit and an antenna. An impedance matching device, characterized in that: