JP2022091619A - Filter circuit - Google Patents

Abstract

To provide a filter circuit capable of suppressing deterioration in a characteristic.SOLUTION: A filter circuit 100 comprises: a filter 10 which is connected between a terminal T1 and a terminal T2, and has a passing band Pass1; a filter 20 which is connected between a terminal T3 and a terminal T4, and includes a passing band Pass2 which does not overlap with the passing band Pass1; a phase shift circuit 11 which is connected between the filter 10 and the terminal T1, and in which a reflection characteristic in the passing band Pass2 viewed from the terminal T1 is set to be an approximate open; and a phase shift circuit 21 which is connected between the filter 20 and the terminal T3, and in which the reflection characteristic in the passing band Pass1 viewed from the terminal T3 is set to be the approximate open.SELECTED DRAWING: Figure 1

Description

The present invention relates to a filter circuit.

Wireless communication devices such as mobile terminals are required to support communication in different frequency bands. Therefore, it has been proposed to connect filters having different pass bands to the antenna without using a switch. In this case, it is known to open the reflection characteristic in the pass band on the other side in order to suppress the deterioration of the characteristic due to the influence of the filters. When three or more filters with different pass bands are connected to the antenna, the imaginary components cancel each other in the pass band of the first filter when looking at other filters excluding the first filter from the common connection point. It has been proposed to suppress the deterioration of characteristics by using such an impedance (for example, Patent Document 1). Further, a method of suppressing characteristic deterioration even when the characteristic impedance is different between the transmission or reception side and the antenna side of the filter has been proposed (for example, Patent Document 2).

Japanese Unexamined Patent Publication No. 2018-74562 Japanese Unexamined Patent Publication No. 2018-137655

It is desired that terminals having different configurations can be connected to the filter circuit for use. For example, select and use two filters, one is to connect between different terminals to make a dual filter, and the other is to connect two filters between a common terminal and two terminals to make a duplexer. It is hoped that it can be done. In this case, it is desirable that deterioration of the characteristics is suppressed even when terminals having different configurations are connected to the filter circuit.

The present invention has been made in view of the above problems, and an object of the present invention is to suppress deterioration of characteristics.

In the present invention, the first filter connected between the first terminal and the second terminal and having the first pass band is connected between the third terminal and the fourth terminal, and overlaps with the first pass band. The second filter having the second pass band is connected between the first filter and the first terminal, and the reflection characteristic in the second pass band when viewed from the first terminal is substantially open. A second phase shift circuit connected between the first phase shift circuit and the second filter and the third terminal, and the reflection characteristics in the first pass band when viewed from the third terminal are substantially open. It is a filter circuit including.

In the above configuration, the reflection characteristic in the first pass band when the first phase shift circuit is viewed from the first terminal is substantially a reference impedance, and when the second phase shift circuit is viewed from the third terminal. The reflection characteristic in the second pass band can be configured to have a substantially reference impedance.

In the above configuration, the first terminal, the second terminal, the third terminal, the fourth terminal, the first filter, the second filter, the first phase shift circuit, and the second phase shift circuit are provided. The first terminal and the second terminal may be configured to be electrically isolated from the third terminal and the fourth terminal on the substrate.

In the above configuration, the first filter and the second filter may be configured to be a bandpass filter.

In the above configuration, a third pass that is connected between the first node and the fifth terminal between the first filter and the first phase shift circuit and does not overlap with the first pass band and the second pass band. A third filter having a band is connected between the second node and the sixth terminal between the second filter and the second phase shift circuit, and the first pass band, the second pass band, and the second pass band are connected. A fourth filter having a fourth pass band that does not overlap with the third pass band is provided, and the first phase shift circuit is connected between the first terminal and the first node, and the first terminal is connected to the first terminal. The reflection characteristics in the second pass band and the fourth pass band when viewed from the above are substantially open, and the second phase shift circuit is connected between the third terminal and the second node, and the second phase circuit is connected. The reflection characteristics in the first pass band and the third pass band when viewed from the three terminals can be substantially open.

In the above configuration, the reflection characteristics in the first pass band and the third pass band when the first phase shift circuit is viewed from the first terminal are substantially reference impedances, and the second transfer from the third terminal. The reflection characteristics in the second pass band and the fourth pass band when the phase circuit is viewed can be configured to have substantially a reference impedance.

In the above configuration, the first terminal, the second terminal, the third terminal, the fourth terminal, the fifth terminal, the sixth terminal, the first filter, the second filter, the third filter, and the like. A substrate provided with a fourth filter, the first phase shift circuit, and the second phase shift circuit is provided, and the first terminal, the second terminal, and the fifth terminal are the third terminal on the substrate. , The fourth terminal and the sixth terminal may be electrically isolated from each other.

In the above configuration, a third phase shift circuit connected between the first node and the first filter and having substantially open reflection characteristics in the third pass band when viewed from the first node, and the above. A fourth phase shift circuit, which is connected between the first node and the third filter and makes the reflection characteristics in the first pass band when viewed from the first node substantially open, and the second node and the above. A fifth phase shift circuit connected between the second filter and substantially open in the reflection characteristics in the fourth pass band when viewed from the second node, and the second node and the fourth filter. The configuration may include a sixth phase shift circuit, which is connected between the two and has a substantially open reflection characteristic in the second pass band when viewed from the second node.

In the above configuration, the first filter, the second filter, the third filter, and the fourth filter may be configured to be a bandpass filter.

In the above configuration, the first phase shift circuit and the second phase shift circuit may be connected to a common terminal via the first terminal and the third terminal.

According to the present invention, deterioration of characteristics can be suppressed.

1 (a) and 1 (b) are circuit diagrams of the filter circuit according to the first embodiment. 2 (a) and 2 (b) are plan views of the filter circuit according to the first embodiment. FIG. 3 is a circuit diagram showing an example of the filter in the first embodiment. 4 (a) and 4 (b) are a plan view and a cross-sectional view showing an example of the elastic wave resonator in the first embodiment. 5 (a) and 5 (b) are circuit diagrams of a filter circuit according to a comparative example. 6 (a) and 6 (b) are Smith charts (No. 1) showing the reflection characteristics in the comparative example in the case of simulation 1. FIG. 7 is a Smith chart (No. 2) showing the reflection characteristics in the comparative example in the case of simulation 1. 8 (a) to 8 (f) are diagrams showing the passing characteristics of the filter in the comparative example in the case of simulation 1. 9 (a) and 9 (b) are Smith charts (No. 1) showing the reflection characteristics in Example 1 in the case of simulation 1. FIG. 10 is a Smith chart (No. 2) showing the reflection characteristics in the first embodiment in the case of the simulation 1. 11 (a) to 11 (f) are diagrams showing the passing characteristics of the filter in the first embodiment in the case of simulation 1. FIG. 12 is an example of a circuit diagram of the phase shift circuit according to the first embodiment. 13 (a) and 13 (b) are Smith charts (No. 1) showing the reflection characteristics in Example 1 in the case of simulation 2. FIG. 14 is a Smith chart (No. 2) showing the reflection characteristics in the first embodiment in the case of the simulation 2. 15 (a) to 15 (f) are diagrams showing the passing characteristics of the filter in the first embodiment in the case of simulation 2. 16 (a) and 16 (b) are circuit diagrams of the filter circuit according to the second embodiment. 17 (a) and 17 (b) are plan views of the filter circuit according to the second embodiment. 18 (a) and 18 (b) are Smith charts (No. 1) showing the reflection characteristics in Example 2. 19 (a) and 19 (b) are Smith charts (No. 2) showing the reflection characteristics in Example 2. 20 (a) and 20 (b) are Smith charts (No. 3) showing the reflection characteristics in Example 2. FIG. 21 is a Smith chart (No. 4) showing the reflection characteristics in Example 2. 22 (a) to 22 (d) are diagrams (No. 1) showing the passing characteristics of the filter in the second embodiment. FIGS. 23 (a) to 23 (d) are diagrams (No. 2) showing the passing characteristics of the filter in the second embodiment.

Hereinafter, examples of the present invention will be described with reference to the drawings.

1 (a) and 1 (b) are circuit diagrams of the filter circuit according to the first embodiment. 1 (a) and 1 (b) have different terminal configurations connected to the filter circuit, FIG. 1 (a) shows a case where the filter circuit is used as a dual filter, and FIG. 1 (b) shows a case where the filter circuit is used as a dual filter. The case where the filter circuit is used as a diplexer or a duplexer is shown. As shown in FIGS. 1A and 1B, the filter circuit 100 includes a filter 10, a phase shift circuit 11, a filter 20, a phase shift circuit 21, and terminals T1 to T4. The filter 10, the phase shift circuit 11, the filter 20, the phase shift circuit 21, and the terminals T1 to T4 are provided on the substrate 60. The filter 10 and the phase shift circuit 11 are connected in series between the terminal T1 and the terminal T2. The filter 20 and the phase shift circuit 21 are connected in series between the terminal T3 and the terminal T4. The filter 10 is, for example, a bandpass filter (BPF) of the pass band Pass 1, and the filter 20 is, for example, a band pass filter (BPF) of the pass band Pass 2. The pass band Pass1 and the pass band Pass2 are different and do not overlap.

As shown in FIG. 1A, when the filter circuit 100 is used as a dual filter, the terminal T1 is connected to the external antenna terminal T11 and the terminal T2 is connected to the external terminal T12. The terminal T3 is connected to the external antenna terminal T21, and the terminal T4 is connected to the external terminal T22. As shown in FIG. 1 (b), when the filter circuit 100 is used as a duplexer or duplexer, the terminal T1 and the terminal T3 are connected to the external common antenna terminal T31, and the terminal T2 is connected to the external terminal T32. T4 is connected to the external terminal T33. A node N is a branch point at which the common antenna terminal T31, the terminal T1 and the terminal T3 branch off.

The phase shift circuit 11 has a substantially open reflection characteristic in the pass band Pass2 of the filter 20 when the phase shift circuit 11 is viewed from the terminal T1. The phase shift circuit 21 has a substantially open reflection characteristic in the pass band Pass1 of the filter 10 when the phase shift circuit 21 is viewed from the terminal T3.

2 (a) and 2 (b) are plan views of the filter circuit according to the first embodiment. FIG. 2A shows a case where the filter circuit is used as a dual filter, and FIG. 2B shows a case where the filter circuit is used as a diplexer or a duplexer. In FIGS. 2A and 2B, the phase shift circuits 11 and 21 provided on the substrate 60 are not shown for the sake of clarity. As shown in FIGS. 2A and 2B, the filter circuit 100 is provided with filters 10 and 20 on the substrate 60. A plurality of foot pads 61 including terminals T1 to T4 are provided on the lower surface of the substrate 60. The filter circuit 100 is mounted on the printed circuit board 90 by the foot pad 61.

As shown in FIG. 2A, when the filter circuit 100 is used as a dual filter, the terminal T1 is connected to the antenna terminal T11 via the wiring 91 of the printed circuit board 90 on which the filter circuit 100 is mounted, and the terminal T2 Is connected to the terminal T12, the terminal T3 is connected to the antenna terminal T21, and the terminal T4 is connected to the terminal T22. As shown in FIG. 2B, when the filter circuit 100 is used as a diplexer or a duplexer, the terminal T1 and the terminal T3 are connected to the common antenna terminal T31 via the wiring 91 of the printed circuit board 90, and the terminal T2 is a terminal. It is connected to T32 and the terminal T4 is connected to the terminal T33.

The terminal T1 is not electrically connected to the terminal T3 and the terminal T4 on the substrate 60. The terminal T2 is not electrically connected to the terminal T3 and the terminal T4 on the substrate 60.

FIG. 3 is a circuit diagram showing an example of the filter in the first embodiment. As shown in FIG. 3, the filters 10 and 20 are ladder type filters in which series resonators S1 to S4 are connected in series between terminals Ta and terminals Tb, and parallel resonators P1 to P3 are connected in parallel. be. The number of series resonators and parallel resonators can be set arbitrarily. The filters 10 and 20 may be multi-mode filters.

4 (a) and 4 (b) are a plan view and a cross-sectional view showing an example of the elastic wave resonator in the first embodiment. FIG. 4A is an example in which the surface acoustic wave resonator is an elastic surface wave resonator. As shown in FIG. 4A, an IDT (Interdigital Transducer) 71 and a reflector 75 are provided on the substrate 70. The IDT 71 has a pair of opposed comb-shaped electrodes 72. The comb-shaped electrode 72 has a plurality of electrode fingers 73 and a bus bar 74 to which the plurality of electrode fingers 73 are connected. Reflectors 75 are provided on both sides of the IDT 71. The IDT 71 excites a surface acoustic wave on the substrate 70. The reflector 75 reflects surface acoustic waves. The substrate 70 is a piezoelectric substrate such as a lithium tantalate substrate or a lithium niobate substrate. The substrate 70 may be a composite substrate in which a piezoelectric substrate is bonded to a support substrate. The support substrate is, for example, a sapphire substrate, a spinel substrate, an alumina substrate, a crystal substrate, or a silicon substrate. An insulating film such as a silicon oxide film or an aluminum oxide film may be provided between the support substrate and the piezoelectric substrate. The IDT 71 and the reflector 75 are formed of a metal film such as an aluminum film or a copper film.

FIG. 4B is an example in which the elastic wave resonator is a piezoelectric thin film resonator. As shown in FIG. 4B, the piezoelectric film 77 is provided on the substrate 70. The lower electrode 76 and the upper electrode 78 are provided so as to sandwich the piezoelectric film 77. A gap 79 is formed between the lower electrode 76 and the substrate 70. The region where the lower electrode 76 and the upper electrode 78 face each other with the piezoelectric film 77 sandwiching at least a part thereof is a resonance region. The lower electrode 76 and the upper electrode 78 in the resonance region excite elastic waves in the thickness longitudinal vibration mode in the piezoelectric film 77. The substrate 70 is, for example, a sapphire substrate, a spinel substrate, an alumina substrate, a glass substrate, a crystal substrate, or a silicon substrate. The lower electrode 76 and the upper electrode 78 are metal films such as a ruthenium film. The piezoelectric film 77 is, for example, an aluminum nitride film. An acoustic reflection film that reflects elastic waves may be provided instead of the gap 79.

[Comparison example]
5 (a) and 5 (b) are circuit diagrams of a filter circuit according to a comparative example. FIG. 5A shows a case where the filter circuit is used as a dual filter, and FIG. 5B shows a case where the filter circuit is used as a diplexer or a duplexer. As shown in FIGS. 5A and 5B, in the filter circuit 500 of the comparative example, the phase shift circuit 11 is not connected to the filter 10, and the phase shift circuit 21 is not connected to the filter 20. Since other configurations are the same as those in the first embodiment, the description thereof will be omitted.

[Simulation 1]
The pass characteristics and reflection characteristics of the filter circuits according to Example 1 and Comparative Example were simulated. In the filter circuit according to the first embodiment, the phase shift circuits 11 and 21 are ideal phase shift circuits. The simulation conditions are as follows.
Filter 10: Pass band Pass1 is 1559 MHz to 1605 MHz (GNSS: L1 band)
Filter 20: Passband Pass2 is 1166 MHz to 1188 MHz (GNSS: L5 band)
Phase shift circuit 11: Phase shift amount is + 35 °
Phase shift circuit 21: Phase shift amount is + 40 °

6 (a) to 7 are Smith charts showing the reflection characteristic S11 in the comparative example in the case of simulation 1. FIG. 6A shows the reflection characteristic S11 when the filter 10 is seen from the terminal T1, and FIG. 6B shows the reflection characteristic S11 when the filter 20 is seen from the terminal T3. FIG. 7 shows the reflection characteristic S11 when the node N is seen from the common antenna terminal T31 when the terminals T1 and T2 are connected to the common antenna terminal T31. The frequency scanning range is 0.5 GHz to 6.0 GHz.

Expressed in polar coordinates, the center of the Smith chart has a radius of 0, and the outer circumference of the Smith chart has a radius of 1. The phase (deviation angle) is 0 ° on the straight line connecting the right end and the center of the Smith chart circle, the phase at the upper end of the circle on the Smith chart is + 90 °, and the phase at the lower end is −90 °. The upper and lower parts of the circle are positive and negative in phase, respectively. When the reflection characteristic S11 is represented by a complex number normalized by a reference impedance (for example, 50Ω), the imaginary part of S11 is 0 on the straight line connecting the right end and the left end of the Smith chart. At the left end, the real part of S11 is 0, and at the right end, the real part of S11 is infinite. In the upper part and the lower part of the circle, the imaginary part of S11 is positive and negative, respectively. Near the outer circumference on the right side of the circle, the absolute value of S11 is close to infinity and is almost open.

In the region 50 near the center of the Smith chart circle, the real part of S11 is near the reference impedance (for example, 50Ω). The closer to the center of the region 50, the closer to the reference impedance. The frequency signal located in the region 50 is less likely to be reflected by the filter 10 or 20 and easily passes through the filter 10 or 20. In the region 51 near the outer circumference on the right side of the circle on the Smith chart, the size of S11 is close to infinity. The frequency signal located in the region 51 is easily reflected by the filter 10 or 20 and is difficult to pass through the filter 10 or 20.

As shown in FIG. 6A, when the filter 10 is viewed from the terminal T1, S11 in the pass band Pass1 of 1559 MHz to 1605 MHz is located near the center of the region 50. Therefore, the high frequency signal in the pass band Pass 1 of the filter 10 passes through the filter 10. The phase of S11 in the pass band Pass2 of 1166 MHz to 1188 MHz is on the negative side of the region 51. Therefore, the high frequency signal in the pass band Pass 2 of the filter 20 is not easily reflected by the filter 10.

As shown in FIG. 6B, when the filter 20 is viewed from the terminal T3, S11 in the pass band Pass2 of 1166 MHz to 1188 MHz is located near the center of the region 50. Therefore, the high frequency signal in the pass band Pass 2 of the filter 20 passes through the filter 20. The phase of S11 in the pass band Pass1 of 1559 MHz to 1605 MHz is on the negative side of the region 51. Therefore, the high frequency signal in the pass band Pass 1 of the filter 10 is not easily reflected by the filter 20.

As shown in FIG. 7, when the node N is viewed from the common antenna terminal T31, S11 in the passband Pass1 of 1559 MHz to 1605 MHz and S11 in the passband Pass2 of 1166 MHz to 1188 MHz are in phase from near the center of the region 50 to the negative side. Is spinning. S11 in the passband Pass1 of 1559 MHz to 1605 MHz is located outside the region 50, and S11 in the passband Pass2 of 1166 MHz to 1188 MHz is located in the periphery of the region 50. This is considered to be due to the following reasons.

As shown in FIG. 6A, when the filter 10 is viewed from the terminal T1, S11 in the pass band Pass2 (1166 to 1188 MHz) of the filter 20 is substantially deviated from the open. Similarly, as shown in FIG. 6B, when the filter 20 is viewed from the terminal T3, S11 in the pass band Pass1 (1559 to 1605 MHz) of the filter 10 is substantially deviated from the open. When the terminals T1 and T3 are connected to the common antenna terminal T31 in such a state, the high frequency signal in the pass band Pass 1 of the filter 10 leaks to the filter 20, and the high frequency signal in the pass band Pass 2 of the filter 20 leaks to the filter 10. Become. That is, it will be affected by the filter of the other party. Therefore, as shown in FIG. 7, when the node N is viewed from the common antenna terminal T31, S11 in the pass band Pass 1 of the filter 10 deviates from the region 50, and S11 in the pass band Pass 2 of the filter 20 is the periphery in the region 50. It is thought that it came to be located in.

8 (a) to 8 (f) are diagrams showing the pass characteristics S21 of the filter in the comparative example in the case of simulation 1. 8 (a) to 8 (c) show the passage characteristic S21 of the filter 10. 8 (d) to 8 (f) show the passage characteristic S21 of the filter 20. 8 (a) to 8 (f), the passage characteristic S21 when the filter circuit 500 is used as a dual filter as shown in FIG. 5 (a) is shown by a solid line as 2in-2out, and is shown in FIG. 5 (b). As described above, the passage characteristic S21 when used as a multiplexer or duplexer is shown by a broken line as 1in-2out.

As shown in FIGS. 8 (a) to 8 (c), when the filter circuit 500 is used as a multiplexer or duplexer (in the case of 1in-2out), and when the filter circuit 500 is used as a dual filter (in the case of 2in-2out). Case), S21 of the filter 10 is deteriorated. As shown in FIGS. 8 (d) to 8 (f), when the filter circuit 500 is used as a multiplexer or duplexer (in the case of 1in-2out), and when the filter circuit 500 is used as a dual filter (in the case of 2in-2out). Case), S21 of the filter 20 is deteriorated.

When the filter circuit 500 is used as a dual filter (in the case of 2in-2out), S21 is good because the filter 10 is seen from the terminal T1 as shown in FIGS. 6A and 6B. In this case, S11 in the pass band Pass 1 (1559 to 1605 MHz) of the filter 10 is located near the center of the region 50, and when the filter 20 is viewed from the terminal T3, S11 in the pass band Pass 2 (1166 to 1188 MHz) of the filter 20 is This is probably because it is located near the center of the region 50. On the other hand, when the filter circuit 500 is used as a multiplexer or duplexer (in the case of 1in-2out), S21 is deteriorated because the node N is seen from the common antenna terminal T31 as shown in FIG. In this case, it is considered that S11 in the pass band Pass 1 (1559 to 1605 MHz) of the filter 10 is out of the region 50, and S11 in the pass band Pass 2 (1166 to 1188 MHz) of the filter 20 is located in the periphery of the region 50. ..

9 (a) to 10 are Smith charts showing the reflection characteristic S11 in the first embodiment in the case of simulation 1. FIG. 9A shows the reflection characteristic S11 when the phase shift circuit 11 is seen from the terminal T1, and FIG. 9B shows the reflection characteristic S11 when the phase shift circuit 21 is seen from the terminal T3. FIG. 10 shows the reflection characteristic S11 when the node N is seen from the common antenna terminal T31 when the terminals T1 and T3 are connected to the common antenna terminal T31. The frequency scanning range is 0.5 GHz to 6.0 GHz.

As shown in FIG. 9A, when the phase shift circuit 11 is viewed from the terminal T1, S11 in the pass band Pass1 of 1559 MHz to 1605 MHz is located near the center of the region 50. Since the phase of the reflection characteristic S11 is rotated positively by the phase shift circuit 11, the phase of S11 in the pass band Pass2 of 1166 MHz to 1188 MHz is located in the region 51 closer to 0 ° as compared with FIG. 6A of the comparative example. is doing.

As shown in FIG. 9B, when the phase shift circuit 21 is viewed from the terminal T3, S11 in the pass band Pass2 of 1166 MHz to 1188 MHz is located near the center of the region 50. Since the phase of S11 is rotated positively by the phase shift circuit 21, the phase of S11 in the pass band Pass 1 of 1559 MHz to 1605 MHz is located in the region 51 closer to 0 ° as compared with FIG. 6 (b) of the comparative example. There is.

As shown in FIG. 10, when the node N is viewed from the common antenna terminal T31, S11 in the passband Pass1 of 1559 MHz to 1605 MHz and S11 in the passband Pass2 of 1166 MHz to 1188 MHz are located near the center of the region 50. .. This is considered to be due to the following reasons.

As shown in FIG. 9A, when the phase shift circuit 11 is viewed from the terminal T1, S11 in the pass band Pass2 (1166 to 1188 MHz) of the filter 20 is located in the region 51 and is substantially open. Similarly, as shown in FIG. 9B, when the phase shift circuit 21 is viewed from the terminal T3, S11 in the pass band Pass1 (1559 to 1605 MHz) of the filter 10 is located in the region 51 and becomes substantially open. There is. When the terminals T1 and T3 are connected to the common antenna terminal T31 in such a state, the high frequency signal of the pass band Pass 1 of the filter 10 is less likely to leak to the filter 20, so that it is less affected by the filter 20 and the pass band of the filter 20. Since the high frequency signal of Pass 2 is less likely to leak to the filter 10, it is less likely to be affected by the filter 10. Therefore, when the node N is viewed from the common antenna terminal T31 as shown in FIG. 10, S11 in the pass band Pass 1 (1559 to 1605 MHz) of the filter 10 and S11 in the pass band Pass 2 (1166 to 1188 MHz) of the filter 20 are It is probable that it continued to be located near the center of the region 50.

11 (a) to 11 (f) are diagrams showing the pass characteristics S21 of the filter in the first embodiment in the case of simulation 1. 11 (a) to 11 (c) show the pass characteristic S21 of the filter 10, and FIGS. 11 (d) to 11 (f) show the pass characteristic S21 of the filter 20. In FIGS. 11 (a) to 11 (f), the passage characteristic S21 when the filter circuit 100 is used as a dual filter as shown in FIG. 1 (a) is shown by a solid line as 2in-2out, and is shown in FIG. 1 (b). As described above, the passage characteristic S21 when used as a multiplexer or duplexer is shown by a broken line as 1in-2out.

As shown in FIGS. 11 (a) to 11 (c), either when the filter circuit 100 is used as a dual filter (in the case of 2in-2out) or when it is used as a multiplexer or duplexer (in the case of 1in-2out). Even in the case of, S21 of the filter 10 was good. As shown in FIGS. 11 (d) to 11 (f), either when the filter circuit 100 is used as a dual filter (in the case of 2in-2out) or when it is used as a multiplexer or duplexer (in the case of 1in-2out). Even in the case of, S21 of the filter 20 was good.

In Example 1, even when the filter circuit 100 is used as a multiplexer or a duplexer (in the case of 1in-2out), S21 of the filters 10 and 20 is improved because the common antenna terminal T31 is shown in FIG. It is considered that S11 in the pass band Pass 1 (1559 to 1605 MHz) of the filter 10 and S11 in the pass band Pass 2 (1166 to 1188 MHz) of the filter 20 are located near the center of the region 50 when the node N is viewed from. ..

[Simulation 2]
Using the phase shift circuits 11 and 21 as specific circuits, the pass characteristics and reflection characteristics were simulated. FIG. 12 is an example of a circuit diagram of the phase shift circuit according to the first embodiment. As shown in FIG. 12, the phase shift circuits 11 and 21 are LCLπ type circuits. A capacitor C1 is connected between the terminal Tc and the terminal Td, and the inductors L1 and L2 are shunt-connected at both ends of the capacitor C1. In the phase shift circuit 11, the terminal Tc is connected to the terminal T1 and the terminal Td is connected to the filter 10. In the phase shift circuit 21, the terminal Tc is connected to the terminal T3, and the terminal Td is connected to the filter 20.

The simulation conditions are as follows.
Filter 10: Pass band Pass1 is 1559 MHz to 1605 MHz (GNSS: L1 band)
Filter 20: Passband Pass2 is 1166 MHz to 1188 MHz (GNSS: L5 band)
Phase shift circuit 11: C1 = 7pF, L1, L2 = 21nH
Phase shift circuit 21: C1 = 4pF, L1, L2 = 13nH

13 (a) to 14 are Smith charts showing the reflection characteristic S11 in the first embodiment in the case of simulation 2. FIG. 13A shows the reflection characteristic S11 when the phase shift circuit 11 is seen from the terminal T1, and FIG. 13B shows the reflection characteristic S11 when the phase shift circuit 21 is seen from the terminal T3. FIG. 14 shows the reflection characteristic S11 when the node N is seen from the common antenna terminal T31 when the terminals T1 and T3 are connected to the common antenna terminal T31. The frequency scanning range is 0.5 GHz to 6.0 GHz.

As shown in FIG. 13A, when the phase shift circuit 11 is viewed from the terminal T1, S11 in the pass band Pass1 of 1559 MHz to 1605 MHz is located near the center of the region 50. Since the phase of the reflection characteristic S11 is rotated positively by the phase shift circuit 11, the phase of S11 in the pass band Pass2 of 1166 MHz to 1188 MHz is located in the region 51 closer to 0 ° as compared with FIG. 6A of the comparative example. is doing.

As shown in FIG. 13B, when the phase shift circuit 21 is viewed from the terminal T3, S11 in the pass band Pass2 of 1166 MHz to 1188 MHz is located near the center of the region 50. Since the phase of the reflection characteristic S11 is rotated positively by the phase shift circuit 21, the phase of S11 in the pass band Pass1 of 1559 MHz to 1605 MHz is located in the region 51 closer to 0 ° as compared with FIG. 6B of the comparative example. is doing.

As shown in FIG. 14, when the node N is viewed from the common antenna terminal T31, S11 in the passband Pass1 of 1559 MHz to 1605 MHz and S11 in the passband Pass2 of 1166 MHz to 1188 MHz continue to be located near the center of the region 50. There is.

15 (a) to 15 (f) are diagrams showing the pass characteristics S21 of the filter in the first embodiment in the case of simulation 2. 15 (a) to 15 (c) show the pass characteristic S21 of the filter 10, and FIGS. 15 (d) to 15 (f) show the pass characteristic S21 of the filter 20. In FIGS. 15 (a) to 15 (f), the passage characteristic S21 when the filter circuit 100 is used as a dual filter as shown in FIG. 1 (a) is shown by a solid line as 2in-2out, and is shown in FIG. 1 (b). As described above, the passage characteristic S21 when used as a multiplexer or duplexer is shown by a broken line as 1in-2out.

As shown in FIGS. 15 (a) to 15 (c), either when the filter circuit 100 is used as a dual filter (in the case of 2in-2out) or when it is used as a multiplexer or duplexer (in the case of 1in-2out). Even in the case of, S21 of the filter 10 was good. As shown in FIGS. 15 (d) to 15 (f), either when the filter circuit 100 is used as a dual filter (in the case of 2in-2out) or when it is used as a multiplexer or duplexer (in the case of 1in-2out). Even in the case of, S21 of the filter 20 was good.

When the phase shift circuits 11 and 21 are concrete circuits, the passing characteristics are slightly worse than when the phase shift circuits 11 and 21 are ideal circuits, but the phase shift circuits 11 and 21 are not provided. Compared with the comparative example, deterioration of passage characteristics can be suppressed.

According to the first embodiment, as shown in FIGS. 1A and 1B, the filter 10 (first filter) having the pass band Pass1 (first pass band) is the terminal T1 (first terminal). It is connected to the terminal T2 (second terminal). A filter 20 (second filter) having a pass band Pass2 (second pass band) that does not overlap with the pass band Pass1 is connected between the terminal T3 (third terminal) and the terminal T4 (fourth terminal). The phase shift circuit 11 (first phase shift circuit) connected between the filter 10 and the terminal T1 is the filter 20 when viewed from the terminal T1 as shown in FIGS. 9A and 13A. The reflection characteristic S11 in the pass band Pass2 (1166 to 1188 MHz) is substantially open. The phase shift circuit 21 (second phase shift circuit) connected between the filter 20 and the terminal T3 is the filter 10 when viewed from the terminal T3 as shown in FIGS. 9 (b) and 13 (b). The reflection characteristic S11 in the pass band Pass1 (1559 to 1605 MHz) is substantially open. As a result, even when the terminals T1 and T3 are connected to the common antenna terminal T31 as shown in FIGS. 10 and 14, when the node N is viewed from the common antenna terminal T31, the reflection characteristics S11 and the reflection characteristic S11 in the pass band Pass1 of the filter 10 The reflection characteristic S11 in the pass band Pass2 of the filter 20 can be set as a substantially reference impedance. Therefore, deterioration of pass characteristics (decrease in loss in the pass band) can be suppressed.

The reflection characteristic S11 is substantially open in the range where the radius is 0.6 or more and the phase is −45 ° or more and + 45 ° or less when the Smith chart is expressed in polar coordinates, and the radius is 0.8 or more. Moreover, the phase may be in the range of −40 ° or more and + 40 ° or less.

As shown in FIGS. 9A and 13A, the reflection characteristic S11 in the pass band Pass1 (1559 to 1605 MHz) of the filter 10 when the phase shift circuit 11 is viewed from the terminal T1 may have a substantially reference impedance. preferable. As shown in FIGS. 9 (b) and 13 (b), the reflection characteristic S11 in the pass band Pass2 (1166 to 1188 MHz) of the filter 20 when the phase shift circuit 21 is viewed from the terminal T3 may have a substantially reference impedance. preferable. As a result, deterioration of pass characteristics (decrease in loss in the pass band) can be suppressed.

The reference impedance of the reflection characteristic S11 is a range in which the radius is 0.5 or less and the radius is 0.4 or less when the Smith chart is expressed in polar coordinates. The radius may be in the range of 0.4 or less. It may be in the range of 0.3 or less. Further, the reflection characteristic S11 in the pass band is a substantially reference impedance when 1/2 or more of the reflection characteristic S11 in the pass band is a substantially reference impedance or when the reflection characteristic S11 in the center frequency of the pass band is a substantially reference impedance. It may be the case that 2/3 or more is substantially the reference impedance.

As shown in FIGS. 1A and 1B, a substrate 60 provided with terminals T1 to T4, filters 10 and 20, and phase shift circuits 11 and 21 is provided. The terminals T1 and T2 are electrically isolated from the terminals T3 and T4 on the substrate 60. In this case, the reflection characteristic S11 in the pass band Pass2 of the filter 20 when the phase shift circuit 11 is viewed from the terminal T1 is substantially open, and the pass band Pass1 of the filter 10 when the phase shift circuit 21 is viewed from the terminal T3 is set. By making the reflection characteristic S11 substantially open, deterioration of the pass characteristic can be suppressed even when the terminals T1 and T3 are connected to the common antenna terminal T31.

Although the case where the filters 10 and 20 are BPFs are shown as an example, they may be high-pass filters or low-pass filters.

16 (a) and 16 (b) are circuit diagrams of the filter circuit according to the second embodiment. 16 (a) and 16 (b) have different terminal configurations connected to the filter circuit, FIG. 16 (a) shows a case where the filter circuit is used as a dual duplexer, and FIG. 16 (b) shows a case where the filter circuit is used. Is used as a quad-plexer. As shown in FIGS. 16A and 16B, the filter circuit 200 includes filters 30 and 31, phase shift circuits 32 to 34, filters 40 and 41, phase shift circuits 42 to 44, and terminals T1 to T6. To prepare for. The filters 30 and 31, the phase shift circuits 32 to 34, the filters 40 and 41, the phase shift circuits 42 to 44, and the terminals T1 to T6 are provided on the substrate 60. The filter 30 is the BPF of the pass band Pass 3, the filter 31 is the BPF of the pass band Pass 4, the filter 40 is the BPF of the pass band Pass 5, and the filter 41 is the BPF of the pass band Pass 6. The pass bands Pass3 to 6 are different from each other and do not overlap.

The filter 30, the phase shift circuit 32, and the phase shift circuit 34 are connected in series between the terminal T1 and the terminal T2, and the filter 31 and the phase shift circuit 33 are the node N1 and the terminal T3 between the phase shift circuits 32 and 34. It is connected in series with. The filter 40, the phase shift circuit 42, and the phase shift circuit 44 are connected in series between the terminal T4 and the terminal T5, and the filter 41 and the phase shift circuit 43 are the node N2 and the terminal T6 between the phase shift circuits 42 and 44. It is connected in series with.

As shown in FIG. 16A, when the filter circuit 200 is used as a dual duplexer, the terminal T1 is connected to the external antenna terminal T41, the terminal T2 is connected to the external terminal T42, and the terminal T3 is an external terminal. It is connected to T43. The terminal T4 is connected to the external antenna terminal T51, the terminal T5 is connected to the external terminal T52, and the terminal T6 is connected to the external terminal T53. As shown in FIG. 16B, when the filter circuit 200 is used as a quad plexer, the terminal T1 and the terminal T4 are connected to the external common antenna terminal T61, and the terminal T2 is connected to the external terminal T62. T3 is connected to the external terminal T63, terminal T5 is connected to the external terminal T64, and terminal T6 is connected to the external terminal T65. The branch point at which the common antenna terminal T61, the terminal T1 and the terminal T4 branch is referred to as a node N3.

The phase shift circuit 32 makes the reflection characteristic in the pass band Pass 4 of the filter 31 when the phase shift circuit 32 is viewed from the node N1 substantially open. The phase shift circuit 33 makes the reflection characteristic in the pass band Pass 3 of the filter 30 when the phase shift circuit 33 is viewed from the node N1 substantially open. The phase shift circuit 34 makes the reflection characteristics in the pass band Pass 5 of the filter 40 and the pass band Pass 6 of the filter 41 when the phase shift circuit 34 is viewed from the terminal T1 substantially open.

The phase shift circuit 42 makes the reflection characteristic in the pass band Pass 6 of the filter 41 when the phase shift circuit 42 is viewed from the node N2 substantially open. The phase shift circuit 43 makes the reflection characteristic in the pass band Pass 5 of the filter 40 when the phase shift circuit 43 is viewed from the node N2 substantially open. The phase shift circuit 44 makes the reflection characteristics in the pass band Pass 3 of the filter 30 and the pass band Pass 4 of the filter 31 when the phase shift circuit 44 is viewed from the terminal T4 substantially open.

17 (a) and 17 (b) are plan views of the filter circuit according to the second embodiment. FIG. 17A shows a case where the filter circuit is used as a dual duplexer, and FIG. 17B shows a case where the filter circuit is used as a quadplexer. In FIGS. 17 (a) and 17 (b), the phase shift circuits 32 to 34 and the phase shift circuits 42 to 44 provided on the substrate 60 are not shown for the sake of clarity. As shown in FIGS. 17 (a) and 17 (b), the filter circuit 200 is provided with filters 30, 31, 40, and 41 on the substrate 60. A plurality of foot pads 61 including terminals T1 to T6 are provided on the lower surface of the substrate 60. The filter circuit 200 is mounted on the printed circuit board 90 by the foot pad 61.

As shown in FIG. 17A, when the filter circuit 200 is used as a dual duplexer, the terminal T1 is connected to the antenna terminal T41 via the wiring 91 of the printed circuit board 90 on which the filter circuit 200 is mounted, and the terminal T2 is used. Is connected to the terminal T42, and the terminal T3 is connected to the terminal T43. The terminal T4 is connected to the antenna terminal T51, the terminal T5 is connected to the terminal T52, and the terminal T6 is connected to the terminal T53. As shown in FIG. 17B, when the filter circuit 200 is used as a quad plexer, the terminal T1 and the terminal T4 are connected to the common antenna terminal T61 via the wiring 91 of the printed circuit board 90, and the terminal T2 is a terminal. It is connected to T62, terminal T3 is connected to terminal T63, terminal T5 is connected to terminal T64, and terminal T6 is connected to terminal T65.

The terminal T1 is not electrically connected to the terminals T4 to T6 on the substrate 60. The terminal T2 is not electrically connected to the terminals T4 to T6 on the substrate 60. The terminal T3 is not electrically connected to the terminals T4 to T6 on the substrate 60.

The filters 30, 31, 40, and 41 are, for example, the ladder type filters shown in FIG. The surface acoustic wave resonator constituting the filter is the elastic surface wave resonator or the piezoelectric thin film resonator shown in FIGS. 4 (a) and 4 (b).

[simulation]
The pass characteristics and the reflection characteristics were simulated using the phase shift circuits 32 to 34 and the phase shift circuits 42 to 44 as specific circuits. The phase shift circuits 32 to 34 and 42, 43 are inductors, and the phase shift circuit 44 is a capacitor.

The simulation conditions are as follows.
Filter 30: Passband Pass3 is 1710 MHz to 1785 MHz (transmission band of band 3)
Filter 31: Pass band Pass4 is 1805 MHz to 1880 MHz (reception band of band 3)
Filter 40: Pass 5 is 1920 MHz to 1980 MHz (transmission band of band 1)
Filter 41: Pass band Pass6 is 2110 MHz to 2170 MHz (reception band of band 1)
Phase shift circuit 32: L = 0.1 nH
Phase shift circuit 33: L = 10nH
Phase shift circuit 34: L = 0.1 nH
Phase shift circuit 42: L = 15nH
Phase shift circuit 43: L = 12nH
Phase shift circuit 44: C = 8pF

18 (a) to 21 are Smith charts showing the reflection characteristic S11 in the second embodiment. FIG. 18A shows the reflection characteristic S11 when the phase shift circuit 32 is seen from the node N1, and FIG. 18B shows the reflection characteristic S11 when the phase shift circuit 33 is seen from the node N1. FIG. 19A shows the reflection characteristic S11 when the phase shift circuit 42 is seen from the node N2, and FIG. 19B shows the reflection characteristic S11 when the phase shift circuit 43 is seen from the node N2. FIG. 20A shows the reflection characteristic S11 when the phase shift circuit 34 is seen from the terminal T1, and FIG. 20B shows the reflection characteristic S11 when the phase shift circuit 44 is seen from the terminal T4. FIG. 21 shows the reflection characteristic S11 when the node N3 is seen from the common antenna terminal T61 when the terminals T1 and T4 are connected to the common antenna terminal T61. The frequency scanning range is 1.5 GHz to 2.7 GHz.

As shown in FIG. 18A, when the phase shift circuit 32 is viewed from the node N1, about 50% of S11 in the pass band Pass 3 of 1710 MHz to 1785 MHz is located in the region 50. By the phase shift circuit 32, S11 in the pass band Pass 4 of 1805 MHz to 1880 MHz is located in the region 51 and is substantially open. As shown in FIG. 18B, when the phase shift circuit 33 is viewed from the node N1, 90% or more of S11 in the pass band Pass 4 of 1805 MHz to 1880 MHz is located in the region 50. By the phase shift circuit 33, S11 in the pass band Pass 3 of 1710 MHz to 1785 MHz is located in the region 51 and is substantially open.

As shown in FIG. 19A, when the phase shift circuit 42 is viewed from the node N2, 90% or more of S11 in the pass band Pass 5 of 1920 MHz to 1980 MHz is located in the region 50. By the phase shift circuit 42, S11 in the pass band Pass 6 of 2110 MHz to 2170 MHz is located in the region 51 and is substantially open. As shown in FIG. 19B, when the phase shift circuit 43 is viewed from the node N2, 80% or more of S11 in the pass band Pass 6 of 2110 MHz to 2170 MHz is located in the region 50. By the phase shift circuit 43, S11 in the pass band Pass 5 of 1920 MHz to 1980 MHz is located in the region 51 and is substantially open.

As shown in FIG. 20A, when the phase shift circuit 34 is viewed from the terminal T1, about 50% of S11 at 1710 MHz to 1880 MHz including the passbands Pass3 and Pass4 is located in the region 50. By the phase shift circuit 34, S11 in the 1920 MHz to 2170 MHz including the pass band Pass5 and Pass6 is located in the region 51 and is substantially open. As shown in FIG. 20B, when the phase shift circuit 44 is viewed from the terminal T4, about 50% of S11 in the 1920 MHz to 2170 MHz including the pass band Pass5 and Pass6 is located in the region 50. By the phase shift circuit 44, S11 in the 1710 MHz to 1880 MHz including the passbands Pass3 and Pass4 is located in the region 51 and is substantially open.

As shown in FIG. 21, when the node N3 is viewed from the common antenna terminal T61, S11 at 1710 MHz to 1880 MHz including the passbands Pass3 and Pass4 and S11 at 1920 MHz to 2170 MHz including the passbands Pass5 and Pass6 are about 50%. It is located in region 50.

22 (a) to 23 (d) are diagrams showing the pass characteristics S21 of the filter in the second embodiment. 22 (a) and 22 (b) show the pass characteristic S21 of the filter 30, and FIGS. 22 (c) and 22 (d) show the pass characteristic S21 of the filter 31, FIGS. 23 (a) and 22 (d). 23 (b) shows the pass characteristic S21 of the filter 40, and FIGS. 23 (c) and 23 (d) show the pass characteristic S21 of the filter 41. In FIGS. 22 (a) to 23 (d), the passage characteristic S21 when the filter circuit 200 is used as a dual duplexer as shown in FIG. 16 (a) is shown by a solid line as 2in-4out, and is shown by a solid line in FIG. 16 (b). As described above, the passage characteristic S21 when used as a quadplexer is shown by a broken line as 1in-4out.

As shown in FIGS. 22 (a) and 22 (b), either the case where the filter circuit 200 is used as a dual duplexer (in the case of 2in-4out) or the case where the filter circuit 200 is used as a quadplexer (in the case of 1in-4out). Even in the case of, S21 of the filter 30 was good. As shown in FIGS. 22 (c) and 22 (d), either the case where the filter circuit 200 is used as a dual duplexer (in the case of 2in-4out) or the case where the filter circuit 200 is used as a quadplexer (in the case of 1in-4out). Even in the case of, S21 of the filter 31 was good.

As shown in FIGS. 23 (a) and 23 (b), either the case where the filter circuit 200 is used as a dual duplexer (in the case of 2in-4out) or the case where the filter circuit 200 is used as a quadplexer (in the case of 1in-4out). Even in the case of, S21 of the filter 40 was good. As shown in FIGS. 23 (c) and 23 (d), either the case where the filter circuit 200 is used as a dual duplexer (in the case of 2in-4out) or the case where the filter circuit 200 is used as a quadplexer (in the case of 1in-4out). Even in the case of, S21 of the filter 41 was good.

According to the second embodiment, as shown in FIGS. 16A and 16B, the filter 30 (first filter) having the pass band Pass 3 (first pass band) is the terminal T1 (first terminal). It is connected to the terminal T2 (second terminal). A filter 40 (second filter) having a pass band Pass 5 (second pass band) that does not overlap with the pass band Pass 3 is connected between the terminal T4 (third terminal) and the terminal T5 (fourth terminal). A filter 31 (third filter) having a pass band Pass 4 (third pass band) that does not overlap with the pass band Pass3 and Pass5 is connected between the node N1 and the terminal T3 (fifth terminal). A filter 41 (fourth filter) having a pass band Pass 6 (fourth pass band) that does not overlap with the pass bands Pass3 to Pass5 is connected between the node N2 and the terminal T6 (sixth terminal).

The phase shift circuit 34 (first phase shift circuit) connected between the terminal T1 and the node N1 has a pass band Pass 5 (1920 to 1920) of the filter 40 when viewed from the terminal T1 as shown in FIG. 20 (a). The reflection characteristic S11 in the pass band Pass6 (2110 to 2170 MHz) of the filter 41 (1980 MHz) is substantially open. The phase shift circuit 44 (second phase shift circuit) connected between the terminal T4 and the node N2 has a pass band Pass3 (1710 to 1710 to) of the filter 30 when viewed from the terminal T4, as shown in FIG. 20 (b). The reflection characteristic S11 in the pass band Pass4 (1805 to 1880 MHz) of the filter 31 (1785 MHz) is substantially open. As a result, even when the terminals T1 and T4 are connected to the common antenna terminal T61 as shown in FIG. 21, when the node N3 is viewed from the common antenna terminal T61, the reflection characteristic S11 in the passbands Pass3 to Pass6 is regarded as a substantially reference impedance. can do. Therefore, deterioration of passage characteristics can be suppressed.

As shown in FIG. 20A, the reflection characteristic S11 in the pass band Pass 3 (1710 to 1785 MHz) of the filter 30 and the pass band Pass 4 (1805 to 1880 MHz) of the filter 31 when the phase shift circuit 34 is viewed from the terminal T1 is omitted. It is preferably the reference impedance. As shown in FIG. 20B, the reflection characteristic S11 in the pass band Pass 5 (1920 to 1980 MHz) of the filter 40 and the pass band Pass 6 (2110 to 2170 MHz) of the filter 41 when the phase shift circuit 44 is viewed from the terminal T4 is omitted. It is preferably the reference impedance. As a result, deterioration of passage characteristics can be suppressed.

As shown in FIGS. 16A and 16B, the substrate 60 is provided with terminals T1 to T6, filters 30, 31, 40, 41, and phase shift circuits 32 to 34, 42 to 44. The terminals T1, T2, and T3 are electrically isolated from the terminals T4, T5, and T6 on the substrate 60. In this case, the reflection characteristic S11 in the pass band Pass 5 of the filter 40 and the pass band Pass 6 of the filter 41 when the phase shift circuit 34 is viewed from the terminal T1 is substantially open, and the phase shift circuit 44 is viewed from the terminal T4. The reflection characteristic S11 in the pass band Pass 3 of the filter 30 and the pass band Pass 4 of the filter 31 is substantially open. As a result, even when the terminals T1 and T4 are connected to the common antenna terminal T61, deterioration of the passing characteristics can be suppressed.

As shown in FIGS. 16A and 18A, the reflection characteristic S11 in the pass band Pass4 (1805 to 1880 MHz) of the filter 31 when viewed from the node N1 is substantially open between the node N1 and the filter 30. It is preferable that the phase shift circuit 32 (third phase shift circuit) is connected. As shown in FIGS. 16A and 18B, the reflection characteristic S11 in the pass band Pass3 (1710 to 1785 MHz) of the filter 30 when viewed from the node N1 is substantially open between the node N1 and the filter 31. It is preferable that the phase shift circuit 33 (fourth phase shift circuit) is connected. As shown in FIGS. 16A and 19A, the reflection characteristic S11 in the pass band Pass6 (2110 to 2170 MHz) of the filter 41 when viewed from the node N2 is substantially open between the node N2 and the filter 40. It is preferable that the phase shift circuit 42 (fifth phase shift circuit) is connected. As shown in FIGS. 16A and 19B, the reflection characteristic S11 in the pass band Pass5 (1920 to 1980 MHz) of the filter 40 when viewed from the node N2 is substantially open between the node N2 and the filter 41. It is preferable that the phase shift circuit 43 (sixth phase shift circuit) is connected. As a result, deterioration of passage characteristics can be suppressed.

As shown in FIG. 18A, it is preferable that the reflection characteristic S11 in the pass band Pass3 (1710 to 1785 MHz) of the filter 30 when the phase shift circuit 32 is viewed from the node N1 has a substantially reference impedance. As shown in FIG. 18B, it is preferable that the reflection characteristic S11 in the pass band Pass 4 (1805 to 1880 MHz) of the filter 31 when the phase shift circuit 33 is viewed from the node N1 has a substantially reference impedance. As shown in FIG. 19A, it is preferable that the reflection characteristic S11 in the pass band Pass 5 (1920 to 1980 MHz) of the filter 40 when the phase shift circuit 42 is viewed from the node N2 has a substantially reference impedance. As shown in FIG. 19B, it is preferable that the reflection characteristic S11 in the pass band Pass 6 (2110 to 2170 MHz) of the filter 41 when the phase shift circuit 43 is viewed from the node N2 has a substantially reference impedance. As a result, deterioration of passage characteristics can be suppressed.

The filters 30, 31, 40, and 41 have shown the case of BPF as an example, but the present invention is not limited to this case, and a high-pass filter or a low-pass filter may be included.

In the second embodiment, the phase shift circuit 34 may have a case where the reflection characteristic S11 in either the pass band Pass 5 of the filter 40 or the pass band 6 of the filter 41 when viewed from the terminal T1 is substantially open. The phase shift circuit 44 may have a case where the reflection characteristic S11 in either the pass band Pass 3 of the filter 30 or the pass band Pass 4 of the filter 31 when viewed from the terminal T4 is substantially open.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such a specific embodiment, and various modifications and variations are made within the scope of the gist of the present invention described in the claims. It can be changed.

10, 20 filter 11, 21 phase shift circuit 30, 31 filter 32, 33, 34 phase shift circuit 40, 41 filter 42, 43, 44 phase shift circuit 50, 51 area 60 board 61 foot pad 70 board 71 IDT
72 Comb-shaped electrode 73 Electrode finger 74 Busbar 75 Reflector 76 Lower electrode 77 Piezoelectric film 78 Upper electrode 79 Void 90 Printed circuit board 91 Wiring 100, 200, 500 Filter circuit

Claims (10)

A first filter connected between the first terminal and the second terminal and having a first pass band,
A second filter connected between the third terminal and the fourth terminal and having a second pass band that does not overlap with the first pass band.
A first phase shift circuit which is connected between the first filter and the first terminal and whose reflection characteristics in the second pass band when viewed from the first terminal are substantially open.
A filter circuit including a second phase shift circuit connected between the second filter and the third terminal and having a reflection characteristic in the first pass band when viewed from the third terminal is substantially open. When the first phase shift circuit is viewed from the first terminal, the reflection characteristic in the first pass band is substantially the reference impedance.
The filter circuit according to claim 1, wherein the reflection characteristic in the second pass band when the second phase shift circuit is viewed from the third terminal is a substantially reference impedance. A substrate provided with the first terminal, the second terminal, the third terminal, the fourth terminal, the first filter, the second filter, the first phase shift circuit, and the second phase shift circuit. ,
The filter circuit according to claim 1 or 2, wherein the first terminal and the second terminal are electrically isolated from the third terminal and the fourth terminal on the substrate. The filter circuit according to any one of claims 1 to 3, wherein the first filter and the second filter are bandpass filters. A second pass band connected between the first node and the fifth terminal between the first filter and the first phase shift circuit and having a third pass band that does not overlap with the first pass band and the second pass band. 3 filters and
It is connected between the second node and the sixth terminal between the second filter and the second phase shift circuit, and does not overlap with the first pass band, the second pass band, and the third pass band. With a fourth filter having a fourth passband,
The first phase shift circuit is connected between the first terminal and the first node, and substantially opens the reflection characteristics in the second pass band and the fourth pass band when viewed from the first terminal. year,
The second phase shift circuit is connected between the third terminal and the second node, and substantially opens the reflection characteristics in the first pass band and the third pass band when viewed from the third terminal. The filter circuit according to claim 1. When the first phase shift circuit is viewed from the first terminal, the reflection characteristics in the first pass band and the third pass band are substantially reference impedances.
The filter circuit according to claim 5, wherein the reflection characteristics in the second pass band and the fourth pass band when the second phase shift circuit is viewed from the third terminal are substantially reference impedances. The first terminal, the second terminal, the third terminal, the fourth terminal, the fifth terminal, the sixth terminal, the first filter, the second filter, the third filter, the fourth filter, A substrate provided with the first phase shift circuit and the second phase shift circuit is provided.
Claim 5 or 6 wherein the first terminal, the second terminal, and the fifth terminal are electrically isolated from the third terminal, the fourth terminal, and the sixth terminal on the substrate. The filter circuit described in. A third phase shift circuit connected between the first node and the first filter and substantially open in the reflection characteristics in the third pass band when viewed from the first node.
A fourth phase shift circuit connected between the first node and the third filter and substantially open in the reflection characteristics in the first pass band when viewed from the first node.
A fifth phase shift circuit connected between the second node and the second filter and substantially open in the reflection characteristics in the fourth pass band when viewed from the second node.
The claim comprises a sixth phase shift circuit which is connected between the second node and the fourth filter and which makes the reflection characteristic in the second pass band substantially open when viewed from the second node. 5. The filter circuit according to any one of 5 to 7. The filter circuit according to any one of claims 5 to 8, wherein the first filter, the second filter, the third filter, and the fourth filter are bandpass filters. The filter circuit according to any one of claims 1 to 9, wherein the first phase shift circuit and the second phase shift circuit are connected to a common terminal via the first terminal and the third terminal.

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