JP2014033377A - Antenna duplexer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna duplexer with two passbands as transmission bands which operates with a single transmission terminal without using a phase shift circuit on the transmission terminal side, and keeps a low insertion loss.SOLUTION: In the antenna duplexer having a first filter with a first passband and a second passband and a second filter with a third passband, the first filter and the second filter are connected to a common antenna terminal.

Description

  The present invention relates to an antenna duplexer mainly used in mobile communication devices and the like.

  There is a need for an antenna duplexer that shares two bands, Band I and Band X, defined by UMTS (UNIVERSAL MOBILE TELECOMMUNICATIONS SYSTEM).

  A conventional antenna duplexer 200 sharing BandI and BandX is shown in FIG. 10, and a conventional antenna duplexer 210 is shown in FIG. 10 is a circuit diagram of a conventional antenna duplexer 200, and FIG. 11 is a circuit diagram of a conventional antenna duplexer 210. 10 and 11, the conventional antenna duplexers 200 and 210 include a first transmission filter 202 having a band I transmission frequency 1920 to 1980 MHz as a pass band, and a second band X transmission frequency 1710 to 1770 MHz as a pass band. Transmission filter 203 and a reception filter 204 having a common reception frequency between 2101 and 2170 MHz for Band I and Band X as a pass band.

  In the conventional antenna duplexer 200, the first transmission filter 202 is connected between the antenna terminal 201 and the first transmission terminal 205, and the second transmission filter 203 is between the antenna terminal 201 and the second transmission terminal 206. The reception filter 204 is connected between the antenna terminal 201 and the reception terminal 207, and the first transmission filter 202, the second transmission filter 203, and the reception filter 204 are commonly connected on the antenna terminal 201 side, and the phase shift is performed. The circuit 208 was connected.

  In the conventional antenna duplexer 210, the first transmission filter 202 and the second transmission filter 203 are connected in parallel between the antenna terminal 201 and the transmission terminal 211, and the reception filter 204 is connected between the antenna terminal 201 and the reception terminal 207. The first transmission filter 202, the second transmission filter 203, and the reception filter 204 are connected in common on the antenna terminal 201 side, and have a configuration in which a phase shift circuit 208 is connected. The transmission filter 202 and the second transmission filter 203 are connected in common and have a configuration in which a phase shift circuit 212 is connected.

  As prior art document information relating to the invention of this application, for example, Patent Document 1 is known.

International Publication No. 2009/011101

  However, when the conventional antenna duplexer 200 is used in a wireless device, two transmission circuits (not shown) corresponding to the first transmission terminal 205 and the second transmission terminal 206 are required. Further, when the conventional antenna duplexer 210 is used, only one transmission circuit (not shown) on the wireless device side connected to the transmission terminal 211 may be used. However, as shown in FIG. In order to connect the first transmission filter 202 and the second transmission filter 203 in common, a phase shifter 212 for adjusting the phase so that each transmission filter has high impedance in the pass band of the other transmission filter is required. Accordingly, in the conventional antenna duplexer 210, the phase shifter 212 is required, which increases the size of the device and increases the cost. Further, in the conventional antenna duplexer 210, there is a problem that the insertion loss also increases because the phase shifter 212 also has a loss.

  The present invention provides an antenna duplexer that operates with one transmission terminal, does not require a phase shift circuit on the transmission terminal side, and has a small insertion loss.

  In order to solve the above problems, the present invention is an antenna duplexer having a first filter having a first passband and a second passband, and a second filter having a third passband. The first filter and the second filter are commonly connected to an antenna terminal.

  With this configuration, the present invention operates with one transmission terminal in an antenna duplexer having two passbands in the transmission band. Therefore, only one transmission circuit may be connected to the transmission terminal, and wireless communication is possible. The device can be simplified. In addition, since the present invention does not require a phase shift circuit on the transmission terminal side, it has an excellent effect that it is possible to obtain a small antenna duplexer with low insertion loss.

Circuit diagram of antenna duplexer according to Embodiment 1 of the present invention Diagram showing passband of the antenna duplexer Circuit diagram of the antenna duplexer Transmission characteristics of the antenna duplexer Reception characteristics of the antenna duplexer Isolation characteristics diagram of the antenna duplexer Circuit diagram of antenna duplexer according to Embodiment 2 of the present invention Circuit diagram of antenna duplexer according to Embodiment 3 of the present invention Circuit diagram of another antenna duplexer according to the third embodiment of the present invention Circuit diagram of conventional antenna duplexer Circuit diagram of another conventional antenna duplexer

  Hereinafter, an elastic wave device according to an embodiment of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a circuit diagram of an antenna duplexer 100 according to Embodiment 1 of the present invention.

  In FIG. 1, the antenna duplexer 100 includes a transmission filter 102 and a reception filter 103. The transmission filter 102 is connected to the antenna terminal 101 and the transmission terminal 104. The reception filter 103 is connected to the antenna terminal 101 and the reception terminal 105. The transmission filter 102 and the reception filter 103 are commonly connected on the antenna terminal 101 side, and are connected to the phase shift circuit 106.

  FIG. 2 is a diagram illustrating the frequency bands of the transmission band and the reception band of Band I and Band X, which are the transmission band and the reception band of the antenna duplexer 100.

  In FIG. 2, the first pass band 21 is the Band I transmission band 1920 to 1980 MHz, the second pass band 22 is the Band X transmission band 1710 to 1770 MHz, and the third pass band 23 is the same for Band I and Band X. The received band is 2110-2170 MHz. The first stop band 31 is outside the band on the high frequency side of the first pass band 21. The second stop band 32 is outside the low band side of the first pass band 21 and out of the high band side of the second pass band 22. The third stop band 33 is outside the band on the low frequency side of the second pass band 22. The first to third stop bands 31, 32, and 33 are defined for convenience in order to explain the characteristics and configuration of the transmission filter of the duplexer of the present invention.

  In the antenna duplexer 100, the transmission filter 102 operates as a filter that uses the first passband 21 and the second passband 22 as passbands and attenuates the third passband 23. The reception filter 103 operates as a filter that uses the third passband 23 as a passband and attenuates the first passband 21 and the second passband 22.

  By setting it as such a structure, the antenna sharing device 100 which can share BandI and BandX is obtained. As described above, the antenna duplexer 100 of the present invention has two transmission bands and operates with one transmission terminal, so that only one transmission circuit is required, and the radio apparatus can be simplified.

  Further, since the antenna duplexer 100 of the present invention does not require a phase shift circuit on the transmission terminal side, loss due to this phase circuit does not occur, thereby realizing an antenna duplexer with low insertion loss.

  FIG. 3 is a circuit diagram showing in more detail the configuration of transmission filter 102 in antenna duplexer 100 according to Embodiment 1 of the present invention.

  As shown in FIG. 3, the transmission filter 102 has four series arm resonance units 5 in series with a signal line connecting the antenna terminal 101 and the transmission terminal 104, and is connected in series with each of the four lines connecting the signal line and the ground. Has a parallel arm resonating portion 6.

  As shown in FIG. 3, each series arm resonance unit 5 is configured by connecting a first resonator 1 and a second resonator 2 in series, and each parallel arm resonance unit 6 includes a third resonator 1. The resonator 3 and the fourth resonator 4 are connected in series. Here, the 1st-4th resonators 1-4 consist of surface acoustic wave resonators.

  The reception filter 103 is configured by connecting one surface acoustic wave resonator (not shown) and one longitudinally coupled filter (not shown) in series.

  In the transmission filter 102, the four first resonators 1 have a resonance frequency of about 1950 MHz and an anti-resonance frequency of about 2020 MHz, and the four second resonators 2 have a resonance frequency of about 1740 MHz and an anti-resonance frequency. The resonance frequency is about 1800 MHz. By designing in this way, each series arm resonance unit 5 has two resonance frequencies (1950 MHz and 1740 MHz) and two anti-resonance frequencies (2020 MHz) corresponding to the first resonator 1 and the second resonator 2. And 1800 MHz).

  In the transmission filter 102, the four third resonators 3 have a resonance frequency of about 1860 MHz and an antiresonance frequency of about 1950 MHz, and the four fourth resonators 4 have a resonance frequency of about 1680 MHz and an antiresonance frequency. The resonance frequency is about 1740 MHz. By designing in this way, each parallel arm resonance unit 6 has two resonance frequencies (1860 MHz and 1680 MHz) and two anti-resonance frequencies (1950 MHz) corresponding to the third resonator 3 and the fourth resonator 4. And 1740 MHz).

  By connecting the four series arm resonance units 5 and the four parallel arm resonance units 6 in a ladder shape, the transmission filter 102 has a bandpass filter having a center frequency around 1950 MHz and a band having a center frequency around 1740 MHz. It functions as a pass filter and has a filter characteristic having two pass bands. In this way, by using a circuit configuration having two pass bands with one transmission filter 102, a phase shift circuit on the transmission terminal side is not required compared to the case where two filters having different pass bands are connected in parallel. There is also an effect that the loss due to the phase shift circuit on the transmission terminal side is eliminated and the performance can be improved. Moreover, since the series arm resonance part 5 and the parallel arm resonance part 6 are the structures by which two resonators are connected in series, it has the effect that the electric power durability calculated | required by the transmission filter of the antenna sharing device 100 becomes high. .

  The antenna duplexer 100 configured as described above is an antenna duplexer having a transmission band having two pass bands, and operates with one transmission terminal without using a phase shift circuit on the transmission terminal 104 side, and is inserted. An antenna duplexer with low loss can be obtained.

  In the circuit shown in FIG. 3, three of the four parallel arm resonating units 6 are commonly connected to the first ground 107. In this way, the amount of attenuation in the third passband 23 which is the stopband of the transmission filter 102 can be increased by commonly connecting three or more parallel arm resonance units 6. Further, by connecting one parallel arm resonating unit 6 of the parallel arm resonating units 6 to a second ground 108 that is not directly electrically connected to the first ground 107, the transmission frequency is doubled or 3 times. It is possible to obtain a large attenuation characteristic in the high frequency region corresponding to the double frequency.

  The electrical characteristics of the antenna duplexer 100 according to the first embodiment of the present invention are shown in FIG. 4, FIG. 5, and FIG.

  FIG. 4 is a diagram showing transmission characteristics that are pass characteristics from the transmission terminal 104 to the antenna terminal 101 of the duplexer according to Embodiment 1 of the present invention. In FIG. 4, the horizontal axis represents frequency, and the vertical axis represents pass characteristics. As can be seen from FIG. 4, the insertion loss is low in the first passband 21 that is the BandI transmission band and the second passband 22 that is the BandX transmission band, and the passband 23 is the common reception band of BandI and BandX. As can be seen from FIG.

  The resonance frequency (1860 MHz) of the third resonator 3 having a relatively high frequency among the resonators constituting the parallel arm resonance unit 6 is relatively low, and the resonance frequency of the third resonator 3 constituting the series arm resonance unit 5 is relatively low. By setting it higher than the anti-resonance frequency (1800 MHz) of the second resonator 2, a frequency between the first passband 21 that is the BandI transmission band and the second passband 22 that is the BandX transmission band is set. Good attenuation characteristics are obtained. In particular, the attenuation band is 30 dB or more between 1800 MHz and 1860 MHz. In this way, by forming an attenuation band between the first passband 21 and the second passband 22, unnecessary signal radiation can be reduced.

  FIG. 5 is a diagram showing pass characteristics from the antenna terminal 101 to the reception terminal 105 of the duplexer according to Embodiment 1 of the present invention. As can be seen from FIG. 5, the insertion loss is low in the third pass band 23, which is a common reception band for Band I and Band X, and the first pass band 21, which is the Band I transmission band, and the second pass band, which is the Band X transmission band. The passband 22 has high attenuation characteristics. The reception filter 103 can be configured by a ladder filter, but the third passband 23 to be passed with low loss and the second passband 22 that needs to have a large attenuation are very different in frequency. Therefore, in order to obtain good attenuation characteristics as shown in FIG. 5, a configuration in which a longitudinally coupled filter and a resonator are combined in series or in parallel is desirable.

  FIG. 6 is a diagram showing pass characteristics from the transmission terminal 104 to the reception terminal 105 of the duplexer according to the first embodiment of the present invention. As can be seen from FIG. 6, in the third pass band 23 that is a common reception band of Band I and Band X, the first pass band 21 that is the Band I transmission band, and the second pass band 22 that is the Band X transmission band. It can be seen that it has a high attenuation characteristic and has an excellent isolation characteristic between the transmission terminal 104 and the reception terminal 105.

  In the antenna duplexer 100 according to Embodiment 1 of the present invention, the phase shift circuit 106 connected to the antenna terminal 101 side has a configuration in which an inductor is shunt-connected between the antenna terminal 101 and the ground 109. For example, an inductor, a strip line, or a microstrip line may be connected in series between the reception filter 103 and the antenna terminal 101.

  In the antenna duplexer 100 according to the first embodiment of the present invention, the first to fourth resonators 4 are configured using surface acoustic wave resonators. However, resonance using an elastic wave such as a boundary wave or a bulk wave is performed. Using a child has the same effect.

  In the antenna duplexer 100 according to the first embodiment of the present invention, the first resonator 1 has a uniform resonance frequency of about 1950 MHz, the antiresonance frequency is uniformly about 2020 MHz, and the second resonator 2 has a resonance frequency. Is uniformly about 1740 MHz, the antiresonance frequency is uniformly about 1800 MHz, the third resonator 3 is uniformly about 1860 MHz, the antiresonance frequency is uniformly about 1950 MHz, and the fourth resonator 4 is Although the resonance frequency is uniformly about 1680 MHz and the anti-resonance frequency is uniformly about 1740 MHz, the resonance frequency and the anti-resonance frequency of the first to fourth resonators 1 to 4 can be varied within a predetermined range. is there.

  That is, each first resonator 1 may be configured to have a resonance frequency in the first pass band 21 and an anti-resonance frequency in the first stop band 31. Each second resonator 2 may be configured to have a resonance frequency in the second passband 22 and an anti-resonance frequency in the second stopband 32. Each of the third resonators 3 may have a resonance frequency in the second stop band 32 and an anti-resonance frequency in the first pass band 21. Each fourth resonator 4 may have a resonance frequency in the third stop band 33 and an anti-resonance frequency in the second pass band 22. By setting the resonance frequency and antiresonance frequency of the first to fourth resonators 1 to 4 within such a range, the transmission filter 102 uses the first and second passbands 21 and 22 as passbands, It is possible to provide a characteristic in which the first to third stop bands 31, 32, and 33 are set as stop bands.

  Then, by making the resonance frequency and antiresonance frequency of the first to fourth resonators 1 to 4 different within the above range, characteristics such as insertion loss, attenuation characteristics, and matching can be optimized. In particular, by setting the resonance frequency and antiresonance frequency of the first resonator 1 closest to the antenna terminal 101 to be higher than the resonance frequency and antiresonance frequency of the other first resonators 1, the pass band of the reception filter 103 is set. 23, the impedance of the transmission filter 102 can be increased, and as a result, the insertion loss of the reception filter 103 can be decreased. Further, in the series arm resonance unit 5 closest to the antenna terminal 101, the impedance of the transmission filter in the passband 23 of the reception filter can be increased by arranging the first resonator 1 on the antenna terminal 101 side. The insertion loss of the reception filter 103 can be reduced.

  Hereinafter, in the second to third embodiments of the present invention, the first resonator 1 has a resonance frequency in the first pass band 21 and an anti-resonance frequency in the first stop band 31. Each of the first resonators 1 can assume different values within this range. The second resonator 2 is a resonator having a resonance frequency in the second pass band 22 and an anti-resonance frequency in the second stop band 32. Different values can be taken within the range. The third resonator 3 is a resonator having a resonance frequency in the second stop band 32 and an anti-resonance frequency in the first passband 21. Different values can be taken within the range. The fourth resonator 4 is a resonator having a resonance frequency in the third stop band 33 and an anti-resonance frequency in the second pass band 22. Different values can be taken within the range.

(Embodiment 2)
FIG. 7 is a circuit diagram showing antenna duplexer 300 according to Embodiment 2 of the present invention. The same components as those of the antenna duplexer 100 according to Embodiment 1 of the present invention shown in FIG.

  The antenna duplexer 300 according to the second embodiment of the present invention differs from the antenna duplexer 100 according to the first embodiment of the present invention in a part of the series arm resonance unit and the parallel arm resonance unit that constitute the transmission filter 302. The point is that three resonators are connected in series. With such a configuration, the power durability of the transmission filter 302 can be improved.

  Specifically, in FIG. 7, the series arm resonance unit 7 has a configuration in which two first resonators 1 and one second resonator 2 are connected in series. The series arm resonance unit 8 has a configuration in which one first resonator 1 and two second resonators 2 are connected in series. The parallel arm resonating unit 9 has a configuration in which two third resonators 3 and one fourth resonator 4 are connected in series. The parallel arm resonance unit 10 has a configuration in which one third resonator 3 and two fourth resonators 4 are connected in series.

  By connecting the two first resonators 1 in series in the series arm resonating unit 7, the combined capacity is reduced to about half compared to the case of one. By connecting the two second resonators 2 in series in the series arm resonating unit 8, the combined capacity thereof is reduced to about half compared to the case of one. By allocating the first and second resonators 1 and 2 between the series arm resonance unit 7 and the series arm resonance unit 8 in this way, desired filter characteristics can be obtained and the number of elements is not significantly increased. Power durability could be improved. In addition, the insertion loss in the first pass band 21 and the insertion loss in the second pass band 22 are reduced in a well-balanced manner while securing a necessary amount of attenuation in the third pass band 23 corresponding to the pass band of the reception filter 103. I was able to design.

  From the viewpoint of avoiding the increase in the size of the element, it is desirable that the series arm resonance unit having the smallest combined capacitance among the series arm resonance units is configured by connecting three resonators in series. It is desirable that the smallest series arm resonance part is provided in the series arm resonance part closest to the antenna terminal.

  By connecting the two third resonators 3 in series in the parallel arm resonating unit 9, the combined capacity is reduced to about half compared to the case of one. By connecting two fourth resonators 4 in series in the parallel arm resonating unit 10, the combined capacity is reduced to about half compared to the case of one. With such a configuration, desired filter characteristics can be obtained and the power durability can be improved without greatly increasing the number of elements. In addition, the insertion loss in the first pass band 21 and the insertion loss in the second pass band 22 are reduced in a well-balanced manner while securing a necessary amount of attenuation in the third pass band 23 corresponding to the pass band of the reception filter 103. It becomes possible to design.

(Embodiment 3)
FIG. 8 is a circuit diagram showing antenna duplexer 400 according to Embodiment 3 of the present invention. The same components as those of the first and second embodiments of the present invention described above are assigned the same numbers, and the description thereof is omitted.

  The antenna duplexer 400 according to the third embodiment of the present invention is different from the antenna duplexer 300 according to the second embodiment of the present invention in that the parallel arm resonating unit 11 closest to the transmission terminal 104 of the transmission filter 402 is connected to the second 3 is configured by connecting three resonators 3 in series. With this configuration, the attenuation of the third passband 23 corresponding to the common reception band of BandI and BandX is reduced while the insertion loss in the first passband 21 corresponding to the BandI transmission band is reduced. Can take bigger.

  FIG. 9 shows a circuit diagram of another antenna duplexer 500 in the third embodiment. As shown in FIG. 9, another antenna duplexer 500 according to the third embodiment is configured such that, in the transmission filter 502, two parallel resonators 12 that are closest to the antenna terminal 101 are connected in series with two third resonators 3. It is configured. With this configuration, the other antenna duplexer 500 according to the third exemplary embodiment can reduce the insertion loss in the first passband 21 corresponding to the BandI transmission band while reducing the common reception band of BandI and BandX. The attenuation of the third passband 23 corresponding to can be made larger.

  Similarly, the serial arm resonance unit of the transmission filter has a configuration in which two first resonators 1 are connected in series, and even if the series arm resonance unit closest to the transmission terminal or the antenna terminal is replaced, Band I The third pass band 23 corresponding to the common reception band of Band I and Band X can be further attenuated while lowering the insertion loss in the first pass band 21 corresponding to the transmission band.

  When the antenna duplexer according to the first to third embodiments of the present invention is configured using a surface acoustic wave, a transmission filter and a reception filter can be configured on the same piezoelectric substrate.

As the piezoelectric substrate, lithium tantalate, lithium niobate, or the like can be used. If the band I and Band X pass band is to be realized by a filter having one pass band, an electromechanical coupling coefficient k ² of about 30% is required. In the antenna duplexer according to the first to third embodiments of the present invention, the electric machine This can be realized if the coupling coefficient k ² is 8% or more, and does not require any special new material, and can be realized by using a piezoelectric substrate that is widely used at present.

  The antenna duplexer according to the present invention operates with one transmission terminal, has two different transmission bands, and is useful in communication devices such as mobile phones.

1, 2, 3, 4 Resonator 5, 7, 8 Series arm resonance unit 6, 9, 10, 11, 12 Parallel arm resonance unit 101 Antenna terminal 102, 302, 402, 502 Transmission filter 103 Reception filter 104 Transmission terminal 105 Reception terminal 106 Phase shift circuit

Claims (12)

A first filter having a first passband and a second passband;
An antenna duplexer having a second filter having a third passband,
The antenna duplexer, wherein the first filter and the second filter are commonly connected to an antenna terminal. The first filter is a ladder filter in which a plurality of series arm resonance units are connected to a signal line connecting a signal terminal and the antenna terminal, and a plurality of parallel arm resonance units are connected between the signal line and the ground. ,
At least one of the series arm resonance units is configured by connecting a first resonator having a resonance frequency fr1 and an anti-resonance frequency fa1, and a second resonator having a resonance frequency fr2 and an anti-resonance frequency fa2. And
At least one of the parallel arm resonating portions is configured by connecting a third resonator having a resonance frequency fr3 and an antiresonance frequency fa3 and a fourth resonator having a resonance frequency fr4 and an antiresonance frequency fa4 connected in series. The frequency relationship between the fr1, the fa1, the fr2, the fa2, the fr3, the fa3, the fr4, and the fa4 is fr2 <fa2 <fr1 <fa1,
fr4 <fa4 <fr3 <fa3,
fr3 <fr1,
fa3 <fa1,
fr4 <fr2 and fa4 <fa2
The antenna duplexer according to claim 1, wherein: The frequency relationship between the fa2 and the fr3 is fa2 <fr3
The antenna duplexer according to claim 2, wherein: 4. The antenna duplexer according to claim 1, wherein the first filter has an attenuation band at a frequency between the first pass band and the second pass band. The at least one series arm resonance unit connects the first resonator and the plurality of second resonators, or the second resonator and the plurality of first resonators in series. The antenna duplexer according to claim 2, which is configured as described above. The at least one parallel arm resonance unit connects the third resonator and the plurality of fourth resonators, or the fourth resonator and the plurality of third resonators in series. The antenna duplexer according to claim 2, which is configured as described above. A first filter having a first passband, a second passband, and a stopband between the first and second passbands, and passing through a position different from the first and second passbands; A second filter having a band; and an antenna terminal commonly connected to the first filter and the second filter, wherein the first filter is connected to a signal line connecting the signal terminal and the antenna terminal. And a parallel arm resonance unit connected between the signal line and the ground, the series arm resonance unit having a resonance frequency in the first passband. A first resonator having a resonance frequency in the second passband and a second resonator having a resonance frequency connected in series; and the parallel arm resonance portion is antiresonant in the first passband. A third resonator having a frequency; and the second resonator Fourth antenna duplexer and a resonator configured by connecting in series with the anti-resonance frequency in the passband. The first resonator has an anti-resonance frequency outside the high band side of the first pass band, and the second resonator has an anti-resonance frequency outside the high band side of the second pass band. The third resonator has a resonance frequency outside the low pass side band of the first pass band, and the fourth resonator is outside the low pass side band of the second pass band. The antenna duplexer according to claim 7, wherein the antenna duplexer has a resonance frequency. The series arm resonance unit is configured by connecting the first resonator and the plurality of second resonators, or the second resonator and the plurality of first resonators in series. The antenna duplexer according to claim 7. The parallel arm resonance unit is configured by connecting the third resonator and the plurality of fourth resonators, or the fourth resonator and the plurality of third resonators in series. The antenna duplexer according to claim 7. The antenna duplexer according to claim 7, wherein the series arm resonance unit is configured by connecting a plurality of the first resonators or a plurality of the second resonators in series. The first filter has a plurality of third resonators or a plurality of fourth resonators connected in series between the signal line and the ground, and another parallel arm resonance unit configured in series. The antenna duplexer according to claim 7.

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