JP3466079B2 - Antenna duplexer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna duplexer which is mainly used in a radio frequency circuit of a radio and has a single antenna shared by a transmitter and a receiver.

[0002]

2. Description of the Related Art In recent years, with the development of mobile communication, antenna duplexers have been used in many mobile phones and car phones. An example of the above-described conventional antenna duplexer will be described below with reference to the drawings.

FIG. 13 is an exploded perspective view of a conventional antenna duplexer. In FIG. 13, 1301 to 1
306 is a dielectric coaxial resonator, 1307 is a coupling substrate, and 13
08 is a metal case, 1309 is a metal cover, 131
0 to 1312 are series capacitors, 1313 and 1314
Is an inductor, 1315 to 1318 are coupling capacitors, 1321 to 1326 are coupling pins, 1331 is a transmitting terminal, 1332 is an antenna terminal, 1333 is a receiving terminal,
Reference numerals 1341 to 1347 are electrode patterns formed on the combined substrate 1307.

Dielectric coaxial resonators 1301, 1302, 1
303 and series capacitors 1310, 1311, 131
2 and the inductors 1313 and 1314 form a transmission band stop filter. In addition, the dielectric coaxial resonator 1304,
1305 and 1306 and coupling capacitors 1315 and 13
Reference numerals 16, 1317 and 1318 form a reception band pass filter.

One end of the transmission filter is connected to a transmission terminal 1331 electrically connected to the transmitter, the other end of the transmission filter is connected to one end of the reception filter and an antenna terminal electrically connected to the antenna. 1332. The other end of the reception filter is connected to a reception terminal 1333 electrically connected to the receiver.

The operation of the antenna duplexer configured as described above will be described below.

First, the transmission band elimination filter exhibits a small insertion loss with respect to the transmission signal in the transmission frequency band, and can transmit the transmission signal from the transmission terminal 1331 to the antenna terminal 1332 with almost no attenuation. In addition, it shows a large insertion loss for the received signal in the received frequency band, and most of the input signal in the received frequency band is reflected, so the received signal input from the antenna terminal returns to the receiving band pass filter. It shows the operation.

On the other hand, the reception band pass filter exhibits a small insertion loss with respect to the reception signal in the reception frequency band, and transmits the reception signal from the antenna terminal 1332 to the reception terminal 1333 with almost no attenuation. You can Further, since a large insertion loss is shown for a transmission signal in the transmission frequency band and most of the input signal in the transmission frequency band is reflected, the transmission signal coming from the transmission filter is sent to the antenna terminal 1332. Show.

An antenna duplexer used in a high frequency band such as mobile communication has a wide and narrow band characteristic, and in order to secure a necessary attenuation amount in a wide band to some extent, cascaded dielectric coaxials are used. The number of resonator stages must be increased.

[0010]

However, in the above configuration, when the number of resonator stages is increased to increase the amount of attenuation, the loss in the signal pass bandwidth is increased. As a measure for avoiding this adverse effect, increasing the unloaded Q of the dielectric coaxial resonator itself can be considered.
In order to increase the size, the volume of the dielectric coaxial resonator itself must be increased, which is contrary to the recent trend toward miniaturization of antenna duplexers.

In view of the above conventional problems, it is an object of the present invention to provide an antenna duplexer having a high attenuation and a low loss without increasing the size of the antenna duplexer.

[0012]

According to a first aspect of the present invention, a transmission input terminal, a reception output terminal, an antenna terminal having a common transmission output terminal and a reception input terminal, the transmission input terminal and the transmission output. A transmission filter provided between terminals and having at least one resonance element coupled by a coupling element, and a reception filter provided between the reception output terminal and the reception input terminal and having at least one resonance element coupled by a coupling element. The filter, the resonance element of the transmission filter, and the resonance element of the reception filter respectively have capacitive elements.
A switching element connected in parallel via a child, and turning on / off the switching element by applying a control signal.
By controlling the frequency transfer characteristic of the transmission filter and the frequency transfer characteristic of the reception filter, the logical configuration of the control signal, a positive DC voltage when ON.
The antenna duplexer is characterized in that it is in an applied state and is in an indeterminate DC voltage value when it is off .

A second aspect of the present invention is a transmission input terminal and a reception output terminal.
Input terminal, the transmission output terminal and the reception input terminal are shared.
Antenna terminal, the transmission input terminal and the transmission output
Provided between terminals, at least connected by a coupling element
A transmission filter having one resonant element, and
Between the input terminal and the receiving input terminal
A receive filter having at least one resonant element coupled thereto
Filter and a resonant element of the transmission filter through a capacitive element.
Switch element connected in parallel with
By switching on and off of the switch element
Control the frequency transfer characteristics of the transmission filter.
However, the logical configuration of the control signal is set to positive DC
When the voltage is applied, the DC voltage value is indefinite when it is off.
The antenna duplexer is characterized by

A third aspect of the present invention is a quarter-wave tip short circuit transmission.
At the open end of multiple dielectric coaxial resonators composed of transmission lines
Connect the capacitive element and connect the other end of the capacitive element to the inductor.
A band stop filter connected by a closet coupling element and 4
Dielectrics composed of half-wavelength short-circuited transmission lines
Connect the open ends of the coaxial resonators with a capacitive coupling element,
Bypasses across the dielectric coaxial resonator and the capacitive coupling element.
And a polar type bandpass filter provided with a circuit,
The output end of the band stop filter and the polar band pass filter
Connect the input terminals of the
Band stop filter and said polar band pass filter respectively
The open ends of one or more of the dielectric coaxial resonators
Frequency composed of series connection of capacitor and switching element
Several frequency shift circuits are connected in parallel to reduce the frequency shift circuit.
Without a resistor, choke coil and bypass capacitor
By applying an externally applied voltage via
The stopband of the filter and the passband of the polar bandpass filter
Antenna characterized by changing overband synchronously
A co for the device.

[0015]

[0016]

[0017]

Further , the present invention provides the above-mentioned one.
Communication device characterized by having an antenna duplexer
is there.

According to the present invention having the above-described structure, the transmission filter and the reception filter can be synchronously varied by external control by adding a switching element and a variable capacitance element to the transmission and reception filter section of the antenna duplexer.
It is possible to control the frequency of the pass band of transmission and reception, which is an important required performance of the duplexer, and as a result, the transmission channel and the reception channel required in the antenna duplexer of the radio will usually change in synchronization, A large amount of attenuation can be obtained with a smaller number of stages than the antenna duplexer. Also, since the number of stages is small, the loss in the pass band can be reduced, and the shape of the antenna duplexer itself can be reduced. Further, when the switch is OFF, the DC voltage value of the terminal is indefinite and excellent characteristics can be obtained when a strong signal is input.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION An antenna duplexer according to a first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram of an antenna duplexer according to the first embodiment of the present invention. In FIG. 1, 101 to 105 are dielectric coaxial resonators composed of quarter-wavelength short-circuited transmission lines, 106 and 107 are series capacitors, 108 and 109 are ground capacitors, 1
10 to 112 are coupled inductors, 113 and 114 are coupled capacitors, 115 and 116 are bypass capacitors,
117 and 118 are capacitors and inductors for matching between terminals, 119 to 123 are switches, and 124 to 128.
Is a capacitor for switch coupling, 129 is an antenna terminal,
Reference numeral 130 is a transmission terminal, and 131 is a reception terminal.

Series capacitors 106 and 107 are connected to the open ends of the dielectric coaxial resonators 101 and 102, and the resonators are coupled by an inductor 110 to form a band elimination filter. Ground capacitors 108 and 109 for suppressing harmonics are connected to both ends of the coupling inductor 110. On the other hand, the dielectric coaxial resonators 103, 104 and 105 are coupled to each other by capacitors 113 and 114, and the input / output coupling inductors 111 and 112 are connected to the open ends of the dielectric coaxial resonators 103 and 105, respectively, to form a band pass filter. Make up. In addition, the bypass capacitor 115 extending across the coupling elements 111 and 113, and the coupling elements 112 and 114.
Attenuation poles are formed on the high frequency side of the pass band by the bypass capacitor 116 extending over. The output end of the transmission band stop filter and the input end of the reception band pass filter are connected to an antenna terminal 129 via a series inductor 118 for matching terminals and a parallel capacitor 117 to form an antenna duplexer. Furthermore, the dielectric coaxial resonator 10
Switch coupling capacitors 124, 125, 126, 12 are provided at the open ends of 1, 102, 103, 104, 105.
Switches 119, 120, 121,
The other end of each switch is grounded.

The operation of the antenna duplexer configured as above will be described below with reference to FIGS. 1 and 2.

First, FIG. 2 shows pass characteristics of the antenna duplexer according to the first embodiment. FIG. 2A shows the pass characteristic of the transmission filter, in which the series capacitor 10 is connected to the transmission line from the transmission terminal 130 to the antenna terminal 129.
Dielectric coaxial resonator 10 grounded via 6, 107
1 and 102 and the interstage coupling inductor 110 form a band elimination filter, and the coupling inductor 110, the series inductor 118 connected to the filter output terminal, and the ground capacitors 108, 109, and 117 form a low-pass characteristic to form a transmission band. It suppresses harmonics. The inductor 118 and the capacitor 117 also play a role of adjusting impedance at the antenna terminal 129 so that the transmitting filter and the receiving filter do not affect each other in their respective frequency bands. The transmission filter shows a small insertion loss with respect to the transmission signal in the transmission frequency band that is the pass band, and hardly attenuates the transmission signal, and the transmission terminal 1
It is possible to transmit from 30 to the antenna terminal 129. Further, since a large insertion loss is shown for a reception signal in the reception frequency band and most of the input signal in the reception frequency band is reflected, the reception signal input from the antenna terminal 129 returns to the reception filter. It shows the operation. Further, FIG. 2B shows the pass characteristics of the reception filter, and the dielectric coaxial resonators 103, 104, 1 grounded to the transmission line from the antenna terminal 129 to the reception terminal 131.
05, the interstage coupling capacitors 113 and 114, and the input / output coupling inductors 111 and 112 constitute a bandpass filter, and the impedance characteristic of the bandpass filter and the capacitor 115 used in the bypass circuit,
The impedance of 116 creates an attenuation pole. In the case of Fig. 1, the impedance of the bypass circuit is equivalently inductive because an inductor is used for input / output coupling.
An attenuation pole will be generated where the impedance of the bandpass filter is capacitive, that is, in the frequency region near the transmission frequency higher than the center frequency of the bandpass filter. The reception filter shows a small insertion loss with respect to the reception signal in the reception frequency band, and can transmit the reception signal from the antenna terminal 129 to the reception terminal 131 with almost no attenuation. In addition, a large insertion loss is shown for a transmission signal in the transmission frequency band, and most of the input signal in the transmission frequency band is reflected, so that the transmission signal coming from the transmission filter is sent to the antenna terminal 129. Show.

Further, the dielectric coaxial resonators 101, 10
At the open ends of 2, 103, 104 and 105, switch coupling capacitors 124, 125 and 1 for blocking direct current are provided.
26, 127, 128 and the switch 11 with one end grounded
Frequency shift circuits configured by serial connection with 9, 120, 121, 122, 123 are connected in parallel. That is, the resonance frequency of the dielectric coaxial resonators 101 to 105 is determined by the capacitance component and the inductance component of the dielectric coaxial resonator itself and the capacitance of the frequency shift circuit when the switches 119 to 123 are ON or OFF. When the switch is turned on, the resonance frequency of the resonator is lowered as the capacitance component is increased, and the center frequency of the filter is lowered, and the stop band of the transmission filter and the pass band of the reception filter are moved toward lower frequencies. When the switch is turned off, the resonance frequency of the dielectric coaxial resonator is increased as the capacitance component decreases. As a result, the center frequency of the filter is raised, and the stop band of the transmission filter and the pass band of the reception filter are moved toward higher frequencies. That is, the stop band of the transmission filter and the pass band of the reception filter can be varied in synchronization.

As a specific circuit configuration used for the switches 119 to 123, there is a circuit using a PIN diode as shown in FIG. Reference numeral 301 denotes a PIN diode, which constitutes a frequency shift circuit by serial connection with a coupling capacitor 302 (corresponding to 124 to 128 in FIG. 1) for blocking a direct current. Switching element 30
1 is connected to the coupling capacitor 302 at the control terminal 30
6, a shift voltage for switching the band is given through a resistor 305, a bypass capacitor 304 and a choke coil 303 so as to be controlled. The shift voltage applied from the control terminal 306 is the PIN diode 3
This is for turning ON / OFF 01. By applying a certain voltage higher than the bias voltage applied to the cathode side, a forward current flows through the PIN diode, which has a very small resistance value and is turned on.
Reference numeral 305 is a resistor for controlling the current value when ON.
On the contrary, when 0V or a reverse bias voltage is applied, the forward current does not flow and has a very large resistance value, which is turned off.

Here, since the antenna duplexer allows transmission signals having strong power to pass through, the power withstanding characteristic is also an important factor. In the configuration of FIG. 3, the bias voltage is 0 V when OFF.
Then, the pass band characteristic of the filter deteriorates due to the influence of the transmission signal power. This is because the PIN diode is momentarily turned on by the electric power leaking to the anode terminal side of the PIN diode 301 at the time of strong input, a part of the signal component is detected, and a DC voltage is generated at the anode terminal. The phenomenon in which this voltage flows to the ground through the control terminal 306 and consequently the loss of the signal component increases becomes dominant.
As a countermeasure against this, if a reverse bias voltage is applied to the control terminal 306, the detection current can be limited. Further, if a bias voltage is applied to both sides of the diode 301 as shown in FIG. 4, a negative voltage is used by applying a positive voltage to the control terminal 402 when it is ON and a positive voltage to the control terminal 403 when it is OFF. Without it, it is possible to apply a reverse bias when OFF. However, in order to completely suppress this deterioration phenomenon, it is necessary to apply a considerably large reverse bias voltage. Therefore, when the control terminal 306 is disconnected at the time of OFF to make the DC voltage value indefinite state, that is, the OPEN state, the above detection current does not flow at all, so loss deterioration cannot occur and the duplexer characteristic at the time of strong input is significantly improved. To do.

FIG. 5 is an experimental result showing the effect, and shows the deterioration amount of the transmission filter insertion loss with respect to the input power level. 501 is a characteristic when the control terminal is OPEN. 502, 503, and 504 set the reverse bias voltage to −
These are the characteristics when 5 V, -3 V, and 0 V are set.
It can be seen that the deterioration amount of the insertion loss at the time of strong input during N control is improved.

Further, the control method in which the control terminal is set to OPEN at the time of OFF uses the function of suppressing the non-linear phenomenon of the PIN diode in its operating principle, and therefore not only the insertion loss is deteriorated but also the distortion characteristic is improved. effective. 6,
7 and 8 show the harmonic characteristic, the adjacent channel leakage power characteristic, and the third-order intermodulation distortion characteristic, respectively, when the diode is OFF, and in both cases, the characteristic during OPEN control is -3.
It can be seen that it is much better than when the V reverse bias voltage is applied. Note that the characteristics of FIG. 8 are values obtained by measuring the signal level appearing at the receiving terminal with one input signal being constant at a level of 30 dBm from the transmitting end and the other being input from the antenna end to be variable.

Here, in the standby state in which the transmission signal is not transmitted, the current consumption of the entire communication device is small, so it is necessary to reduce the current consumption of the antenna duplexer as much as possible. Therefore, since the transmission filter is not used during standby, there is no problem in actual use even if the switch for controlling the transmission band is always in the OFF state, and the current consumption during standby can be reduced.

Further, the PIN diode is switched from ON to OFF.
When switching to the positive voltage, when the positive voltage is applied and the voltage is momentarily changed to the indefinite state, the charge remaining on the anode side of the diode does not discharge immediately, but discharges with a certain time constant, and as a result, the switch The switching speed may be slow. At that time, if the control is switched to the voltage indefinite state by instantaneously grounding or applying a reverse bias voltage, the residual charge of the anode is instantaneously discharged and the deterioration of the switching speed can be prevented.

Further, the transmission filter has a circuit configuration in which a band stop filter and a low pass filter are combined, and the coupling capacitor 10 which constitutes the low pass filter.
One end of 9, 117 needs to be grounded, but if they are simply connected to a common ground terminal, they are electrically coupled through this ground electrode, and the attenuation characteristics of the low-pass filter deteriorate. Figure 9
FIG. 3 is a mounting circuit diagram of the duplexer near the antenna terminal, and the same elements as those in FIG. 1 are denoted by the same reference numerals. Reference numeral 901 is an antenna terminal, 902 is a ground terminal adjacent to the antenna terminal in the direction of the transmission side, and 903 is a ground terminal adjacent to the antenna terminal in the direction of the reception side. As shown in FIG.
Ground terminal 902 separated by antenna terminal 901
By connecting capacitors 109 and 117 to and 903, respectively, electrical coupling via the ground electrode can be greatly reduced, and the attenuation characteristic of the filter can be improved.
Further, the same effect can be obtained by providing ground electrodes spaced apart from each other and grounding them.

For the switch elements 119 to 123, transistors can be used in addition to the PIN diode described above. For example, FIG. 10 shows an example in which a field effect transistor (FET) 1001 is used as a switching element. The gate electrode of the FET is a bypass capacitor 1
It is connected to the control terminal 1003 via 002. FET
Is a voltage control element, it does not generate current consumption when the diode is on, which is effective in reducing current consumption. Further, if a varactor diode is used as the switch element, the band can be continuously changed.

The relationship between the pass characteristics of the transmission filter and the reception filter for frequencies of 800 to 1000 megahertz based on the above configuration is as shown in FIG. 20 of FIG. 2 (a)
Reference numeral 203 in 1 and (b) is a pass characteristic when the switch is ON, and when the switch is OFF, 20 in FIG.
2, 204 in (b). In this way, by switching the switch, the frequencies of the transmission stop band and the reception pass band of the antenna duplexer are changed in synchronization.

As described above, according to the present embodiment, the stop band of the transmission filter and the pass band of the reception filter of the antenna duplexer can be controlled in synchronization with the externally applied voltage, and a wide band can be obtained to some extent. Even in this case, the amount of attenuation can be obtained without increasing the number of filter stages. Also, since the number of stages is small, the loss is reduced. As a result, the shape of the antenna duplexer itself can be reduced. Furthermore, by setting the control terminal to OPEN when the switch is OFF, it is possible to prevent characteristic deterioration when a strong power signal is input.

An antenna duplexer according to a second embodiment of the present invention will be described below with reference to the drawings.

FIG. 11 is a circuit configuration diagram of an antenna duplexer according to the second embodiment of the present invention. Figure 1
1, 1101 to 1106 are dielectric coaxial resonators composed of a quarter wavelength tip short-circuited transmission line, 110
7, 1108 are series capacitors, 1109 and 1110 are ground capacitors, 1111 to 1113 are coupled inductors, 1114 to 1116 are coupled capacitors, 111
7, 1118 are bypass capacitors, 1119, 112
0 is a capacitor and inductor for matching between terminals, 112
1, 1122 is a switch, 1123, 1124 are switch coupling capacitors, 1125 is an antenna terminal, 112
6 is a transmission terminal and 1127 is a reception terminal.

Series capacitors 1107 and 1108 are connected to the open ends of the dielectric coaxial resonators 1101 and 1102, and the resonators are coupled by an inductor 1111 to form a band elimination filter. Ground capacitors 1109 and 111 for suppressing harmonics are provided at both ends of the coupling inductor 1111.
0 is connected. On the other hand, the dielectric coaxial resonator 110
3, 1104, 1105, and 1106 are capacitors 111
Input / output coupling inductors 1112 and 1113, which are coupled to each other by 4, 1115 and 1116, are connected to open ends of the dielectric coaxial resonators 1103 and 1106, respectively, to form a reception bandpass filter. Also, coupling elements 1112, 1
Bypass capacitor 1117 across 114 and bypass capacitor 111 across coupling elements 1113, 1116
8 forms an attenuation pole on the high frequency side of the pass band. The output end of the band stop filter and the input end of the band pass filter are series inductors 1120 for matching terminals.
And the antenna terminal 11 via the parallel capacitor 1119.
It is connected to 25 and constitutes an antenna duplexer. Further, switches 1121 and 1122 are connected to the open ends of the dielectric coaxial resonators 1101 and 1102 via switch coupling capacitors 1123 and 1124, and the other ends of the switches are all grounded.

The operation of the antenna duplexer configured as described above will be described below with reference to FIGS. 11 and 12.

First, FIG. 12 shows the pass characteristics of the antenna duplexer of the second embodiment. FIG. 12A shows the pass characteristics of the transmission filter, which is the dielectric coaxial resonators 1101 and 1102 and the inter-stage coupling inductor which are grounded via the series capacitors 1107 and 1108 to the transmission line from the transmission terminal 1126 to the antenna terminal 1125. 111
1 constitutes a band elimination filter, and the coupling inductor 1111 and the series inductor 1120 connected to the filter output end and the ground capacitors 1109, 1110, 1
A low-pass characteristic is formed by 119 to suppress transmission band harmonics. Inductor 1120 and capacitor 111
Reference numeral 9 also plays a role of adjusting impedance at the antenna terminal 1125 so that the transmitting side filter and the receiving side filter do not affect in each frequency band.
The transmission filter exhibits a small insertion loss with respect to the transmission signal in the transmission frequency band which is the pass band, and can transmit the transmission signal from the transmission terminal 1126 to the antenna terminal 1125 with almost no attenuation. Further, since a large insertion loss is shown for a reception signal in the reception frequency band and most of the input signal in the reception frequency band is reflected, the reception signal input from the antenna terminal 1125 returns to the reception filter. Indicates. In addition, FIG.
(B) shows the pass characteristics of the reception filter, which are dielectric coaxial resonators 1103, 1104, 1105, which are grounded to the transmission line from the antenna terminal 1125 to the reception terminal 1127.
1106 and interstage coupling capacitors 1114, 111
5, 1116 and input / output coupling inductors 1112, 11
A bandpass filter is constituted by 13, and an attenuation pole is generated by the impedance characteristic of the bandpass filter and the impedance of the capacitors 1117 and 1118 used in the bypass circuit. In the case of FIG. 11, the impedance of the bypass circuit is equivalently inductive because an inductor is used for coupling the input and output, and the impedance of the bandpass filter is capacitive, that is, higher than the center frequency of the bandpass filter. An attenuation pole will be created in the frequency domain. The reception filter shows a small insertion loss with respect to the reception signal in the reception frequency band, and can transmit the reception signal from the antenna terminal 1125 to the reception terminal 1127 with almost no attenuation. Further, since a large insertion loss is shown for a transmission signal in the transmission frequency band and an input signal in the transmission frequency band is almost reflected, the transmission signal coming from the transmission filter is sent to the antenna terminal 1125. Show.

Further, the dielectric coaxial resonators 1101 and 11
A frequency shift circuit configured by a series connection of switch coupling capacitors 1123 and 1124 for blocking a direct current and switches 1121 and 1122 whose one ends are grounded is connected in parallel to the open end of 02. That is, the resonance frequency of the dielectric coaxial resonators 1101 and 1102 is determined by the capacitance component and the inductance component of the dielectric coaxial resonator itself and the capacitance of the frequency shift circuit when the switches 1121 and 1122 are ON or OFF. When the switch is turned on, the resonance frequency of the resonator is lowered as the capacitance component increases, and the center frequency of the filter is lowered, and the stop band of the transmission filter is moved in the lower frequency direction. When the switch is turned off, the resonance frequency of the dielectric coaxial resonator is increased as the capacitance component decreases. As a result, the center frequency of the filter is raised and the pass band of the stop band of the transmission filter is moved in the direction of higher frequency. That is, only the stop band of the transmission filter can be varied while the pass band characteristic of the reception filter is fixed. As a result, compared to the first embodiment, the number of stages of the reception filter is increased and the insertion loss is increased, but the number of shift circuit units is reduced, so that the circuit current consumption can be reduced.

The relationship between the transmission characteristics of the transmission filter and the reception filter for frequencies of 800 to 1000 megahertz based on the above configuration is shown in FIG. Figure 1
Reference numeral 1201 in 2 (a) is the pass characteristic of the transmission filter when the switch is ON, and it is 12 when the switch is OFF.
It becomes the characteristic of 02. 4. The reception filter has the pass characteristic 1203 of FIG. 12B regardless of the operation of the switch. In this way, only the frequency of the stop band of the transmission filter of the antenna duplexer is changed by switching the switch.

The circuit configurations of the switches 1121 and 1122 are P shown in FIGS. 3 and 4 as in the first embodiment.
The IN diode, the FET shown in FIG. 10, the varactor diode, or the like can be used, in which case the same effect as that of the first embodiment can be obtained.

As described above, according to the present embodiment, by controlling only the stop band of the transmission filter of the antenna duplexer by the externally applied voltage, the number of filter stages is increased as in the first embodiment. The amount of attenuation can be obtained without Also, since the number of stages is small, the loss is reduced. As a result, the shape of the antenna duplexer itself can be reduced. Furthermore, by setting the control terminal to OPEN when the switch is OFF, it is possible to prevent characteristic deterioration when a high power signal is input.
Furthermore, low current consumption at the time of reception will be realized.

In the first and second embodiments, the resonator is a dielectric coaxial resonator, but it may be a stripline resonator. Further, the filter has a band-stop filter on the transmitting side and a band-pass filter on the receiving side. Needless to say, it is included.

Further, in the first and second embodiments, the case where the switch circuit is used in the antenna duplexer has been described, but the control method, particularly the O of the PIN diode is used.
The means for improving the deterioration of the strong input characteristic of the filter when the DC voltage is indefinite during FF is not limited to the antenna duplexer,
It can also be applied to a filter or a switch circuit that controls pass characteristics using an N diode.

In the first and second embodiments, the capacitor is used to connect the resonant element and the variable impedance element in parallel, but an inductor may be used.

The present invention is most effective for a communication device for a system having a wide transmission pass band and a wide reception pass band and a very narrow interval between the transmission pass band and the reception pass band, and PCS, E- GSM, CDMA of Japan, etc. correspond to this. For example, the transmission pass band and the reception pass band are each divided into two parts with a bandwidth corresponding to each other to form a transmission low band, a transmission high band, a reception low band, and a reception high band. The transmission band and the reception band are synchronously switched by giving a control signal to each of the two divided bands, and the reception L is set to the transmission Low.
ow and transmission High correspond to reception High. As a result, the transmission / reception frequency interval during operation becomes equivalently wide, and the amount of attenuation can be secured without increasing the number of filter stages. The system can cover the entire transmission pass band and the entire reception pass band by selecting the band in which the channel to be used is present according to the control signal. In addition, it goes without saying that the configuration of the present invention can be applied to other TD
It can also be used in MA and CDMA systems.

[0049]

As is clear from the above description, the present invention can realize an antenna duplexer with high attenuation and low loss without increasing the size of the antenna duplexer.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of an antenna duplexer according to a first embodiment of the present invention.

FIG. 2 is a pass characteristic diagram of the antenna duplexer for explaining the operation in the first embodiment.

FIG. 3 is a configuration diagram of a shift circuit using a PIN diode according to the first embodiment.

FIG. 4 is a configuration diagram of a shift circuit using a PIN diode according to the first embodiment.

FIG. 5 is a characteristic diagram of insertion loss with respect to input signal power of the antenna duplexer according to the first embodiment.

FIG. 6 is a characteristic diagram of the second harmonic with respect to the input signal power of the antenna duplexer in the first embodiment.

FIG. 7 is a characteristic diagram of adjacent channel leakage power with respect to input signal power of the antenna duplexer in the first embodiment.

FIG. 8 is a characteristic diagram of third-order intermodulation distortion with respect to input signal power of the antenna duplexer in the first embodiment.

FIG. 9 is a circuit board mounting diagram in the vicinity of the antenna terminal according to the first embodiment.

FIG. 10 is a configuration diagram of a shift circuit using the FET according to the first embodiment.

FIG. 11 is a circuit configuration diagram of an antenna duplexer according to a second embodiment of the present invention.

FIG. 12 is a pass characteristic diagram of the antenna duplexer for explaining the operation in the second embodiment.

FIG. 13 is an exploded perspective view of a conventional antenna duplexer.

[Explanation of symbols] 101-105 resonator 119-123 switch 124-128 capacitors 129 Antenna terminal 130 transmission terminal 131 receiving terminal

─────────────────────────────────────────────────── ─── Continuation of front page (72) Hideyuki Miyake 55-12 Ozumihama, Kyotanabe-shi, Kyoto Prefecture Matsushita Nitto Electric Co., Ltd. (72) Toshio Ishizaki 1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric Industrial Co., Ltd. In-house (72) Inventor Makoto Fujikawa 55-12 Ozumihama, Kyotanabe-shi, Kyoto Prefecture Matsushita Nitto Electric Co., Ltd. (72) Inventor Hideki Hayama 4-3-1 Tsunashima East, Kohoku Ward, Yokohama City, Kanagawa Matsushita Communication Industrial Co. In-house (56) Reference JP-A-8-172333 (JP, A) JP-A-7-336267 (JP, A) JP-A-7-22814 (JP, A) JP-A-7-321509 (JP, A) ) JP-A-6-152202 (JP, A) JP-A-7-131203 (JP, A) JP-A-63-9303 (JP, A) JP-A-7-297627 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H01P 1/213 H0 1P 1/205 H04B 1/40

Claims (8)

(57) [Claims] 1. A transmission input terminal, a reception output terminal, an antenna terminal in which a transmission output terminal and a reception input terminal are shared, and a transmission input terminal and a transmission output terminal, which are connected by a coupling element. A transmission filter having at least one resonance element, a reception filter having at least one resonance element provided between the reception output terminal and the reception input terminal and coupled by a coupling element, a resonance element of the transmission filter, and A switch connected in parallel to the resonance element of the reception filter through a capacitive element, respectively.
An element, and the switch is applied by applying a control signal.
The frequency transfer characteristic of the transmission filter and the frequency transfer characteristic of the reception filter are controlled by switching the ON / OFF of the switching element to turn on the logical configuration of the control signal.
The positive DC voltage is applied when
An antenna duplexer that is in a fixed state . 2. A standby mode in which a transmission signal is not transmitted, the switch element for controlling the pass band of the transmission filter is always turned off, and the frequency transfer characteristic is controlled only by the reception filter. Antenna duplexer. 3. A transmission input terminal, a reception output terminal, and a transmission
Antenna terminal with common output terminal and reception input terminal
And between the transmission input terminal and the transmission output terminal.
And at least one resonator element coupled by a coupling element.
A transmission filter having a child, the reception output terminal and the reception
A small number of elements connected between the input terminals and coupled by a coupling element
A receive filter having at least one resonant element;
Is connected in parallel to the resonance element of the signal filter through the capacitive element.
It is equipped with a switch element, and by applying a control signal
By switching the switch element on and off,
Controlling the frequency transfer characteristic of the transmission filter,
Set the signal logic configuration to the positive DC voltage applied state when ON.
However, when it is off, the DC voltage value is indefinite.
Antenna duplexer. 4. A positive voltage in the logical configuration of the control signal.
When switching from the voltage application state to the indefinite voltage value,
Characterized by applying a negative voltage or negative voltage
The antenna duplexer according to claim 1 or 3. 5. The frequency transfer characteristic of the transmission filter is a band.
It is a band rejection type, and the frequency transfer characteristic of the receiving filter is
It is a band pass type, and the frequency transfer characteristics of the transmission filter are
A plurality of capacitive elements that simultaneously have a low-pass type and form the low-pass type frequency transfer characteristic.
Connect one terminal of the child to multiple independent ground terminals.
Separately connected, and the multiple ground terminals are formed on both sides of the antenna terminal.
The antenna sharing according to claim 1, characterized in that
vessel. 6. The switching element is a PIN diode.
And a control terminal is provided at both ends of the PIN diode.
6. The antenna according to claim 5, wherein
Instrument 7. A quarter-wavelength short-circuited transmission line is used.
Capacitor element is connected to the open end of multiple dielectric coaxial resonators
The other end of the capacitive element is connected to the inductance coupling element.
Band stop filter connected by and quarter-wave tip
Opening of multiple dielectric coaxial resonators composed of short-circuited transmission lines
Connect the discharge ends with a capacitive coupling element
Provided a bypass circuit across the resonator and the capacitive coupling element
And a band-pass filter having a polarized band-pass filter.
The output end of the filter and the input end of the polarized bandpass filter.
A common terminal is continuously provided, and the band stop filter is provided.
And one or more of each of the polar bandpass filters
Connect the coupling capacitor and switch to the open end of the dielectric coaxial resonator.
A frequency shift circuit composed of series connection of
The frequency shift circuit is connected in parallel with at least a resistor.
External application via choke coil and bypass capacitor
Blocking the band-stop filter by applying a voltage
Synchronize the band and the pass band of the polarized band pass filter
An antenna duplexer that is characterized by changing it. 8. The method according to any one of claims 1 to 7.
A communication device including the antenna duplexer
Bowl .