JP7433168B2 - Composite filter and communication device - Google Patents

Description

The present disclosure relates to a composite filter having two or more filters, and a communication device including the composite filter.

Composite filters having two or more filters are known. Patent Documents 1 and 2 disclose duplexers as composite filters. A duplexer consists of a transmission filter that filters the high frequency signal (transmission signal) input from the transmission terminal and outputs it to the antenna, and a reception filter that filters the high frequency signal (reception signal) input from the antenna and outputs it to the reception terminal. have. In Patent Documents 1 and 2, the transmission filter and the reception filter are connected to the antenna via a 90° hybrid in order to improve the isolation between the transmission filter and the reception filter.

International Publication No. 2009/078095 Special table 2015-530810 publication

A composite filter and a communication device that can reduce nonlinear distortion are awaited.

A composite filter according to an aspect of the present disclosure includes a common terminal, a first terminal, a second terminal, a first filter system connecting the common terminal and the first terminal, and a first filter system connecting the common terminal and the first terminal. a second filter system connected to the second terminal, and the first filter system and the second filter system share a 180° hybrid connected to the common terminal. , the 180° hybrid includes a first port, a second port and a third port that are electrically connected to the first port, and a fourth port that is electrically connected to the second port and the third port. The second port and the third port are ports to which signals of the same phase are distributed from the first port, and the fourth port is a port to which signals of the same phase are distributed from the third port to the first port. A signal having a phase shifted by 180° from the phase of the signal to be distributed is distributed from the third port, the first port is connected to the common terminal, and the first filter system includes: a first filter connected to the second port and corresponding to the first passband; a 90° phase shifter connected to the third port; A second filter is connected to the three ports and corresponds to the first pass band, and the first filter and the second filter are connected to the first terminal, and the first terminal and the second filter are connected to the first terminal. an auxiliary circuit that shifts the phase of a signal flowing between the first terminal and the second filter by 90 degrees with respect to a signal flowing between the first terminal and the second filter; The third filter corresponds to a second passband different from the first passband and connects the fourth port and the second terminal.

A communication device according to an aspect of the present disclosure includes the composite filter, an antenna connected to the common terminal, and an integrated circuit element connected to the first terminal and the second terminal. There is.

According to the above configuration, nonlinear distortion can be reduced.

FIG. 2 is a circuit diagram showing the configuration of a duplexer according to the first embodiment. FIGS. 2(a) and 2(b) are schematic diagrams for explaining the operation of a 90° hybrid, and FIGS. 2(c) and 2(d) are schematic diagrams for explaining the operation of a 180° hybrid. It is a diagram. 3(a) and 3(b) are schematic diagrams for explaining the operation of the composite filter of FIG. 1. FIG. FIG. 2 is a circuit diagram showing the configuration of a composite filter according to a second embodiment. FIG. 7 is a circuit diagram showing the configuration of a composite filter according to a third embodiment. 2 is a plan view schematically showing an example of the configuration of a resonator included in the duplexer of FIG. 1. FIG. 2 is a circuit diagram schematically showing an example of the configuration of a duplexer main body included in the duplexer of FIG. 1. FIG. 8 is a plan view showing an example of a chip included in the duplexer main body of FIG. 7. FIG. FIGS. 9(a) and 9(b) are schematic diagrams showing an example of a 180° hybrid configuration and other examples. FIGS. 10(a), 10(b), and 10(c) are plan views showing examples of the structure of the duplexer according to the embodiment. 1 is a block diagram showing a configuration of a communication device as an example of using a duplexer according to an embodiment. FIG. FIG. 3 is a circuit diagram showing the configuration of a composite filter according to a fourth embodiment. FIG. 3 is a circuit diagram showing the configuration of a composite filter according to a fifth embodiment. FIG. 2 is a schematic diagram showing an example of a 180° hybrid configuration. FIG. 2 is a circuit diagram showing an example of the structure of a duplexer according to an embodiment.

Embodiments according to the present disclosure will be described below with reference to the drawings. Note that the diagrams used in the following explanation are schematic. Therefore, for example, the dimensional ratios, etc. on the drawings do not necessarily match the reality.

After describing the first embodiment, basically only the differences from the previously described embodiments will be described. Items that are not specifically mentioned may be the same as those in the previously described embodiments, or may be inferred from the previously described embodiments.

In this disclosure, when referring to "shifting a phase" or the like, the phase may be advanced or delayed. However, for convenience, when specifying and explaining the amount of shift, "shifting the phase" shall mean only one of them. For example, when describing the function of multiple elements (e.g. phase shifter) in one composite filter as "shifting the phase by 90 degrees," it is assumed that all of the multiple elements have the function of advancing the phase by 90 degrees, or that none of the multiple elements has the function of advancing the phase by 90 degrees. It has the function of delaying the phase by 90 degrees. Also, for example, when one element has two terminals and the phases of a signal flowing from one terminal to the other terminal and a signal flowing from the other terminal to one terminal are shifted by 90 degrees, the above two signals The phases are both advanced by 90 degrees or delayed by 90 degrees. For a phase shift of 180°, the above distinction is not necessary.

<First embodiment>
(Outline of duplexer)
FIG. 1 is a circuit diagram showing the configuration of a duplexer 1 as a composite filter according to the first embodiment.

More specifically, the branching filter 1 is configured as a duplexer. The duplexer 1 includes, for example, a transmission filter system 2T that filters the transmission signal from the transmission terminal 7 and outputs it to the antenna terminal 5, and a reception filter that filters the reception signal from the antenna terminal 5 and outputs it to the reception terminal 9. system 2R.

The transmission filter system 2T includes transmission filters 13A and 13B (hereinafter sometimes referred to as "transmission filter 13" without distinguishing between the two, or both collectively), which are directly responsible for filtering the transmission signal. ing. Further, the reception filter system 2R includes a reception filter 15 that directly performs filtering of the reception signal. The transmission filter 13 corresponds to the transmission band. The reception filter 15 corresponds to the reception band. In other words, the transmission filter 13 and the reception filter 15 have different passbands. Note that a portion of the duplexer 1 that includes the transmission filter 13 and the reception filter 15 and directly contributes to filtering is sometimes referred to as the duplexer main body 3.

It is known that nonlinear distortion (distortion signal) such as intermodulation distortion (IMD) occurs in the transmission filter 13 and/or the reception filter 15 due to its nonlinearity. Note that in this disclosure, unless otherwise specified, intermodulation distortion has a broad meaning including passive intermodulation distortion (PIM). This nonlinear distortion deteriorates the characteristics of the duplexer 1. More specifically, for example, if the frequency of nonlinear distortion in the transmission filter 13 is located within the passband of the reception filter 15, the nonlinear distortion passes through the reception filter 15 and is input to the reception terminal 9, resulting in a decrease in reception sensitivity. decreases.

Therefore, the duplexer 1 includes a 90° hybrid 17, a 90° phase shifter 19 (hereinafter sometimes simply referred to as "phase shifter 19"), and a 180° hybrid 21. These elements distribute, phase adjust, and/or combine the transmitted and/or received signals. In this process, for example, nonlinear distortions are distributed, the distributed nonlinear distortions are made to have opposite phases, and then are combined and cancel each other out. That is, nonlinear distortion is reduced. On the other hand, the duplexer 1 basically maintains the strength of the transmitted signal and the received signal.

The transmission filter system 2T and the reception filter system 2R share the 180° hybrid 21. The 180° hybrid 21 is connected to the antenna terminal 5. In the 180° hybrid 21, a transmission filter system 2T and a reception filter system 2R are branched from each other.

The transmission filter system 2T has a 90° hybrid 17 connected to the transmission terminal 7. The signal path from the transmission terminal 7 to the antenna terminal 5 is branched at the 90° hybrid 17, and a transmission filter 13A is located on one path, and a transmission filter 13B is located on the other path. There is. The transmission filters 13A and 13B correspond to the same pass band. The transmission filter 13A is directly connected to the 180° hybrid 21 (in other words, in a manner in which the phase is not shifted). The transmission filter 13B is connected to a 180° hybrid via a phase shifter 19 that shifts the phase by 90°. A terminating resistor 23 is connected to an unused port 17a of the 90° hybrid 17.

The reception filter system 2R includes the reception filter 15 as described above. The reception filter 15 is directly connected to the 180° hybrid 21 and the reception terminal 9 (in other words, in a manner in which the phases are not shifted).

(filter)
The transmission filter 13 is a bandpass filter whose passband is a predetermined transmission band. Similarly, the reception filter 15 is a bandpass filter whose passband is a predetermined reception band. The transmission band and the reception band may be in accordance with various standards, for example. Furthermore, the transmission band may include two or more transmission bands that comply with a predetermined standard. The same applies to the reception band.

Transmission filters 13A and 13B correspond to the same transmission band. That is, the passbands of the transmission filters 13A and 13B are substantially and/or the same in design. The transmission filters 13A and 13B have the same or similar configuration, and substantially or in design, have the same characteristics. However, the transmission filters 13A and 13B may be finely adjusted so that their passbands are slightly different and/or their characteristics are slightly different. For example, since the transmission filters 13A and 13B differ in terms of whether or not the phase shifter 19 is connected, etc., fine adjustments may be made to reduce the influence of the difference on the signal.

The specific configuration of the transmission filter 13 and the reception filter 15 may be a known configuration or an application of a known configuration. For example, the transmission filter 13 and/or the reception filter 15 may be a piezoelectric filter containing a piezoelectric substance, a dielectric filter that utilizes electromagnetic waves in a dielectric, or an LC filter that combines an inductor and a capacitor. It may be a filter or a combination of two or more of these. The piezoelectric filter may, for example, use elastic waves or may not (eg, use a piezoelectric vibrator). The elastic wave is, for example, a SAW (Surface Acoustic Wave), a BAW (Bulk Acoustic Wave), a boundary acoustic wave, or a plate wave (although these elastic waves are not necessarily distinguishable).

(90° hybrid)
As is well known, the 90° hybrid 17 has four ports 17a to 17d for signal input and/or output, and also functions as a distributor, combiner, and 90° phase shifter. have. The configuration of the 90° hybrid 17 may be a known configuration or an application of a known configuration. For example, although not particularly shown, the 90° hybrid 17 may be of a distributed constant type or a lumped constant type. Note that a branch line coupler is well known as the 90° hybrid 17.

FIG. 2A is a schematic diagram showing an example of the operation of the 90° hybrid 17. FIG. 2(b) is a schematic diagram showing another example of the operation of the 90° hybrid 17.

In the illustrated example, ports 17a and 17b on the left side of the paper are electrically connected to ports 17c and 17d on the right side of the paper, respectively. Continuity here means that a signal can flow. Therefore, for example, as shown in FIG. 2(a), a signal input to port 17a can be output from ports 17c and 17d.

For convenience, the present embodiment may be explained based on the positional relationship of the ports 17a to 17d in a diagram showing the 90° hybrid 17. However, the positional relationship of the four ports 17a to 17d on the diagram does not have to match the actual positional relationship of the four ports 17a to 17d. The same applies to ports of other elements (for example, ports 21a to 21d of the 180° hybrid 21), which will be described later.

As shown in FIG. 2A, the signal s1 input to the port 17a on the left side of the page is distributed to the ports 17c and 17d on the right side of the page and output as signals s1-0 and s1-90. The distribution ratio at this time (ratio between the intensity of the signal s1-0 and the intensity of the signal s1-90) is 1:1. Note that the intensity is, for example, voltage, current, and/or power. The phase of the signal s1-0 is, for example, the same as the phase of the signal s1. On the other hand, the phase of the signal s-90 is shifted by 90° from the phase of the signal s1-0, for example.

Note that, similarly below, there may be a certain phase difference between the signal s1 before distribution and the signals s1-0 and s1-90 after distribution. The essence of the 90° hybrid is that the phase of the signal s1-0 and the phase of the signal s1-90 are shifted by 90°. However, in the description of this embodiment, for convenience, the signal s1 before distribution and the signal s1-0 after distribution may be described as having the same phase.

The above operation is similar when signals are input to the other ports 17b to 17d. In other words, a signal input to one of the two ports located on one side of the paper in the horizontal direction is distributed at a distribution ratio of 1:1 and output from the two ports located on the other side of the paper in the horizontal direction. Ru. At this time, the phase of the signal output from the port located on the opposite side in the vertical direction of the paper from the port into which the signal was input is the same as the phase of the signal output from the port located on the same side in the vertical direction in the paper relative to the port into which the signal was input. It is shifted by 90 degrees from the phase of the signal output from the .

Incidentally, since a device that operates as described above is called a 90° hybrid, the relationship among the four ports of the 90° hybrid 17 can be specified only from the explanation regarding some of the ports. For example, assume that the port 17d is a port to which a signal whose phase is shifted by 90 degrees from the phase of the signal distributed from the port 17a to the port 17c is distributed from the port 17a. From this explanation, it can be seen that the port 17a and the remaining ports 17b are located on the same side in the left-right direction of the paper, and the ports 17c and 17d are located on the opposite side, and that the port 17a and the port 17c are located on the same side in the vertical direction of the paper. It is derived that the port 17b and the port 17d are located on the opposite side. When the relationship between the four ports is explained by the signals distributed from the port 17a as described above, the 90° hybrid 17 does not need to be provided in such a manner that the signal is actually input from the port 17a. None.

As shown in FIG. 2(b), when the signal s1 is input to the port 17a on the left side of the page and the signal s2 is simultaneously input to the port 17b on the left side of the page, the signals s1 and s2 are distributed as described above. signals are combined. For example, at the port 17c, a signal s1-0 is distributed from the signal s1 and has the same phase as the signal s1, and a signal s2-90 is distributed from the signal s2 and has a phase 90° shifted from the phase of the signal s2. The combined signal is output. At port 17d, a signal s1-90, which is distributed from the signal s1 and has a phase shifted by 90 degrees from the phase of the signal s1, is combined with a signal s2-0, which is distributed from the signal s2 and has the same phase as that of the signal s2. signal is output. Although the case where signals are input to the two ports 17a and 17b on the left side of the page is illustrated, the same applies to the case where signals are input to the two ports 17c and 17d on the right side of the page. Note that, as described above, there may be a phase difference between the signal s1 and the signal s1-0, and there may be a phase difference between the signal s2 and the signal s2-0. At this time, the above two phase differences are the same. The two phase differences when the signals are in opposite directions are also the same as the above two phase differences.

Returning to FIG. 1, the port 17a is connected to the terminating resistor 23. Port 17b is connected to transmission terminal 7. Port 17c is connected to transmission filter 13A. Port 17d is connected to transmission filter 13B. Therefore, for example, when a signal is input to the transmission terminal 7, the signal is distributed at a distribution ratio of 1:1 with a phase difference of 90 degrees, and is input to the transmission filters 13A and 13B.

(terminal resistor)
The terminating resistor 23 has, for example, a predetermined resistance value, and connects the port 17a and a reference potential section (not shown). This reduces reflection of signals flowing from ports 17c and/or 17d to port 17a. The resistance value of the terminating resistor 23 may be appropriately set according to the impedance on the 90° hybrid 17 side than the terminating resistor 23, but is generally 50Ω. The configuration of the terminating resistor 23 may be a known configuration or an application of a known configuration. For example, although not particularly illustrated, the terminating resistor 23 may be an electronic component mounted on a circuit board, or may be a conductive pattern formed on the circuit board.

(phase shifter)
The configuration of the phase shifter 19 may be a known configuration or an application of a known configuration. For example, the phase shifter 19 may be of a distributed constant type or a lumped constant type. The phase shifter 19 mediates between the transmission filter 13B and the 180° hybrid 21. The phase shifter 19 shifts the phase of the signal flowing from the transmission filter 13B to the 180° hybrid by 90°, and also shifts the phase of the signal flowing from the 180° hybrid to the transmission filter 13B by 90°.

(180° hybrid)
As is well known, the 180° hybrid 21 has four ports 21a to 21d for signal input and/or output, and also functions as a distributor, combiner, and 180° phase shifter. have. The configuration of the 180° hybrid 21 may be a known configuration or an application of a known configuration. For example, although not particularly shown, the 180° hybrid 21 may be of a distributed constant type or a lumped constant type. Note that a rat race is well known as the 180° hybrid 21.

FIG. 2(c) is a schematic diagram showing an example of the operation of the 180° hybrid 21. FIG. 2(d) is a schematic diagram showing another example of the operation of the 180° hybrid 21.

In the illustrated example, the ports 21b and 21d on the left and right sides of the paper are electrically connected to the ports 21a and 21c on the top and bottom of the paper, respectively. Continuity here means that a signal can flow. Therefore, for example, as shown in FIG. 2(c), a signal input to port 21b can be output from ports 21a and 21c. Similarly, as shown in FIG. 2(d), a signal input to port 21d can be output from ports 21a and 21c.

As shown in FIG. 2C, the signal s3 input to the port 21b on the left side of the page is distributed to the ports 21a and 21c on the top and bottom of the page and output as two signals s3-0. The distribution ratio at this time is 1:1. The operation is similar when signals are input to the other ports 21a, 21c, and 21d. That is, a signal input to one of the four ports is distributed at a distribution ratio of 1:1 and output from the other two ports that are electrically connected to the port to which the signal was input. 2(c) and 2(d) illustrate cases where signals are input to ports 21b and 21d located on the left and right sides of the page, but signals are input to ports 21a and 21c located at the top and bottom of the page. The same applies if

Although not particularly shown, when a signal is input to two ports that are not electrically connected to each other (a combination of ports 21a and 21c on the top and bottom of the page, or a combination of ports 21b and 21d on the left and right sides of the page), it is distributed as described above. The signals are combined and output from the other two ports. For example, when signals are input to ports 21a and 21c at the top and bottom of the page, some signals are distributed from the signal input to port 21a, and some signals are distributed from the signal input to port 21c. A combined signal is output from port 21b, and a combined signal of the remaining signal distributed from the signal input to port 21a and the remaining signal distributed from the signal input to port 21c is output from port 21d. Output.

When a signal is distributed from one port to another port as described above, for example, the phase of the output signal is shifted by 180° with respect to the phase of the input signal between the port 21c and the port 21d. It will be done. This is the same whether the signal is input to either port 21d or 21c. On the other hand, between other ports, the phase of the input signal and the phase of the output signal are, for example, the same. Therefore, for example, as shown in FIG. 2(d), when the signal s4 is input to the port 21d, a signal s4-0 that is distributed from the signal s4 and has the same phase as the signal s4 is output from the port 21a. , signal s4, and a signal s4-180 having a phase 180° out of phase with that of signal s4 is output from port 21c.

The same applies below, but there is a constant value between the signal s4 before distribution and the signals s4-0 and s4-180 after distribution, and between the signal s3 before distribution and the signal s3-0 after distribution. There may be a phase difference of The essence of the 180° hybrid is that the phases of the signal s4-0 and the signal s4-180 are 180° out of phase. In case there is a phase difference between the signal s3 and the signal s3-0, between the signal s4 and the signal s4-0, as well as other similar signals, the phase differences are the same as each other. In the description of this embodiment, for convenience, the signal s4 (or s3) before distribution and the signal s4-0 (or s3-0) after distribution may be described as having the same phase.

Since a device that operates as described above is called a 180° hybrid, the relationship among the four ports of the 180° hybrid 21 can be specified only from the description of some of the ports. For example, assume that it has been explained that the port 21a and the port 21c are ports to which signals having the same phase are distributed from the port 21b. Then, the ports numbered 180 are either between ports 21a and 21d or between ports 21c and 21d. Assume that the port 21d is a port to which a signal whose phase is shifted by 180 degrees from the phase of the signal distributed from the port 21c to the port 21b is distributed from the port 21c. This establishes the relationship between the four ports. When the relationship between the four ports is explained by the signals distributed from the predetermined ports as described above, the 180° hybrid 21 is provided in such a manner that the signals are actually input from the predetermined ports. There's no need to be there.

Returning to FIG. 1, port 21a is connected to transmission filter 13A. Port 21b is connected to antenna terminal 5. Port 21c is connected to transmission filter 13B via phase shifter 19. Port 21d is connected to reception filter 15. Therefore, for example, two signals input from the transmission filters 13A and 13B to the 180° hybrid 21 are partially combined and output to the antenna terminal 5, and the remaining signals are combined (as described later). cancel each other out).

(Operation of composite filter)
FIG. 3A is a diagram illustrating the operation of the duplexer 1 when a signal (for example, a transmission signal) is input to the transmission terminal 7. In this figure, the flow of signals is shown by arrows. Furthermore, as shown by the legend on the right side of the paper, the line types of the arrows are changed depending on the change in the phase of the signal. Here, the phase of the signal flowing through the transmission terminal 7 is set to 0°.

A signal input from the transmission terminal 7 to the 90° hybrid 17 is divided into a signal with a phase of 0° and a signal with a phase of 90°. Of these, the signal with a phase of 90° passes through the transmission filter 13A and is input to the port 21a of the 180° hybrid 21. On the other hand, after passing through the transmission filter 13B, the signal with a phase of 0° is converted into a signal with a phase of 90° by the phase shifter 19, and is input to the port 21c. Therefore, the two signals that have passed through the transmission filters 13A and 13B are in phase with each other and input to the ports 21a and 21c.

The two signals that are distributed from the two signals input to the ports 21a and 21c and flow to the port 21b are combined while maintaining the same phase and are output to the antenna terminal 5. On the other hand, the two signals that are distributed from the two signals input to ports 21a and 21c and flow to port 21d are opposite to each other because the phase of one (the signal flowing from port 21c to port 21d) is shifted by 180 degrees. It is considered to be the phase. As a result, the two signals cancel each other out. That is, no signal is output to the reception filter 15.

As described above, the signal input from the transmission terminal 7 is output to the antenna terminal 5, but is not output to the reception filter 15 (reception terminal 9). Also, for convenience of explanation, it has been expressed that the two signals input to ports 21a and 21c are distributed and flow to port 21d, but the fact that no signal is output from port 21d means that the signal is actually distributed to port 21d. This means that it has not been done. That is, if insertion loss is ignored, the strength of the signal output from the antenna terminal 5 is the same as the strength of the signal input to the transmission terminal 7.

FIG. 3B is a diagram illustrating the operation of the duplexer 1 when a signal (for example, a received signal) is input to the antenna terminal 5. In this figure, the flow of signals input to the antenna terminal 5 is shown by arrows. Further, as in FIG. 3A, the line type of the arrow is changed depending on the change in the phase of the signal. Here, the phase of the signal flowing through the antenna terminal 5 is set to 0°.

A signal input from the antenna terminal 5 to the port 21b of the 180° hybrid 21 is distributed to the ports 21a and 21c, and flows to the transmission filters 13A and 13B. Signals (for example, received signals) outside the passbands of transmission filters 13A and 13B are reflected by transmission filters 13A and 13B and return to ports 21a and 21c. At this time, the signal output from the port 21c passes through the phase shifter 19 twice: when going to the transmission filter 13B and when returning from the transmission filter 13B. As a result, the phase of the signal returned to port 21c is shifted by 180° from the phase of the signal returned to port 21a. That is, two signals having mutually opposite phases are input to ports 21a and 21c.

The two signals that are distributed from the two signals input to ports 21a and 21c and flow to port 21b maintain opposite phases. Therefore, both cancel each other out. That is, no signal is output to the antenna terminal 5. On the other hand, the two signals that are distributed from the two signals input to ports 21a and 21c and flow to port 21d are in phase with each other because the phase of one (the signal flowing from port 21c to port 21d) is shifted by 180°. It is said that As a result, the two signals are combined and output to the reception filter 15.

As described above, the signal input from the antenna terminal 5 is output to the reception filter 15 (reception terminal 9), but is not output to the transmission terminal 7. Also, for convenience of explanation, it was expressed that the two signals input to ports 21a and 21c are distributed and flowed to port 21b, but the fact that no signal is output from port 21b means that the signal is actually distributed to port 21b. This means that it has not been done. That is, if insertion loss is ignored, the strength of the signal input to the reception filter 15 is the same as the strength of the signal input to the antenna terminal 5.

(Nonlinear distortion)
Elements constituting the transmission filter 13 and the reception filter 15 may have nonlinearity. For example, in a piezoelectric filter, the relationship between the stress applied to the piezoelectric body and the strain (not the nonlinear strain here, but the ratio of the amount of deformation) generated in the piezoelectric body is ideally linear. However, when the stress reaches a certain level, distortion becomes difficult to generate and even reaches saturation. That is, the characteristics of the piezoelectric material are nonlinear, in which input and response are not proportional. As a result, nonlinear distortion (distorted signal) occurs when one or more signals with relatively high power are input to the filter.

For example, assume that the frequencies of two signals (input voltages) input to the filter are f1 and f2, and m and n are integers (...-3, -2, -1, 0, 1, 2, 3...). At this time, in the filter, a signal (an output voltage and an output current from another point of view) having a frequency of m×f1+n×f2 is generated. |m|+|n| is called the degree. A signal in which |m|+|n| is 2 or more is nonlinear distortion. A signal in which both m and n are not 0 has intermodulation distortion (in a broad sense). A signal in which one of m and n is 0 is a harmonic.

Various signals can be cited as the two signals that cause nonlinear distortion. For example, in a duplexer 1 that is shared by two or more frequency bands in a base station or the like, two transmission signals are simultaneously input to the transmission terminal 7. Further, examples include interference waves (noise) from the antenna terminal 5 and a transmission signal input to the transmission terminal 7.

In the description of this embodiment, when simply referring to nonlinear distortion, unless otherwise specified, the values of m and n are arbitrary. For example, the nonlinear distortion may be a third-order nonlinear distortion where m = 2 and n = -1, a third-order nonlinear distortion where m = 2 and n = 1, or an odd-order nonlinear distortion. It may be nonlinear distortion or even-order nonlinear distortion.

The composite filter of this embodiment can reduce the possibility that among these nonlinear distortions, nonlinear distortions in which |m|+|n| is an odd number will flow into the reception filter 15 side. Here, assume that two signals are input to the transmission terminal 7 and nonlinear distortion occurs in the transmission filter 13. At this time, two nonlinear distortions (nonlinear distortions in which the frequencies m×f1+n×f2 are equal), the nonlinear distortion generated in the transmitting filter 13A and the nonlinear distortion generated in the transmitting filter 13B, are input to the transmitting terminal 7. Similar to the two signals distributed to the transmission filters 13A and 13B in the 90° hybrid 17, they have a phase difference of 90°. Therefore, similar to the signal described with reference to FIG. 3(a), although nonlinear distortion is input from the 180° hybrid 21 to the antenna terminal 5, it is not input to the reception filter 15 (reception terminal 9).

As described above, in this embodiment, the composite filter (brancher 1) has a common terminal (antenna terminal 5), a first terminal (transmission terminal 7), a second terminal (reception terminal 9), and an antenna terminal. The first filter system (transmission filter system 2T) connects the antenna terminal 5 and the transmission terminal 7, and the second filter system (reception filter system 2R) connects the antenna terminal 5 and the reception terminal 9. are doing. The transmission filter system 2T and the reception filter system 2R share a 180° hybrid 21 connected to the antenna terminal 5. The 180° hybrid 21 includes a first port (port 21b), a second and third ports (ports 21a and 21c) that are electrically connected to the port 21b, and a fourth port (ports 21a and 21c) that are electrically electrically connected to the ports 21a and 21c. It has a port 21d). Port 21a and port 21c are ports to which signals having the same phase are distributed from port 21b. The port 21d is a port to which a signal whose phase is shifted by 180 degrees from the phase of the signal distributed from the port 21c to the port 21b is distributed from the port 21c. Port 21b is connected to antenna terminal 5. The transmission filter system 2T includes a first filter (transmission filter 13A), a 90° phase shifter 19, a second filter (transmission filter 13B), and an auxiliary circuit (90° hybrid 17). The transmission filter 13A is connected to the port 21a and corresponds to the first pass band (transmission band). Phase shifter 19 is connected to port 21c. The transmission filter 13B is connected to the port 21c via the phase shifter 19, and corresponds to the transmission band. The 90° hybrid 17 connects transmission filters 13A and 13B to the transmission terminal 7, and changes the phase of the signal flowing between the transmission terminal 7 and the transmission filter 13A to the signal flowing between the transmission terminal 7 and the transmission filter 13B. Shift 90° from the The reception filter system 2R includes a reception filter 15. The reception filter 15 corresponds to a second passband (reception band) different from the transmission band (does not overlap with the transmission band), and connects the port 21d and the reception terminal 9.

Therefore, for example, as described above, the two nonlinear distortions generated in the two transmission filters 13A and 13B cancel each other out in the 180° hybrid 21, and the nonlinear distortion input to the reception filter 15 is reduced (theoretically, it disappears). ). As a result, the receiving sensitivity of the duplexer 1 is improved. In a known configuration in which the 180° hybrid 21 is not provided, the transmitting signal flowing from the transmitting terminal 7 to the antenna terminal 5 via the transmitting filter 13 is reflected by the receiving filter 15 and is thereby changed to the receiving terminal 9. is suppressed. On the other hand, in this embodiment, as described with reference to FIG. 3A, the flow of the transmission signal to the reception filter 15 in the 180° hybrid 21 is suppressed. As a result, for example, isolation is improved (theoretically, the absolute value (dB) of isolation becomes infinite). Further, for example, since the transmission signal input to the transmission terminal 7 is distributed by the 90° hybrid 17 and input to the two transmission filters 13A and 13B, the transmission signal is input to only one transmission filter 13. The power applied to one transmission filter 13 is reduced compared to . As a result, the electric resistance of the transmission filter system 2T is improved. Further, when the transmission filter 13 is a piezoelectric filter, vibrations are reduced by reducing the applied voltage, so nonlinear distortion is reduced. For example, while obtaining various effects regarding the signal from the transmitting terminal 7 side as described above, as explained with reference to FIG. 3(b), the received signal input from the antenna terminal 5 may be can be input to the reception filter 15 while maintaining the same.

Each of the first filter (transmission filter 13A), second filter (transmission filter 13B), and third filter (reception filter 15) may be a piezoelectric filter.

In this case, for example, high frequency and/or narrow band filter characteristics can be obtained. On the other hand, the occurrence of nonlinear distortion is inevitable due to the nonlinearity of the piezoelectric material. However, according to the duplexer 1 according to the embodiment, nonlinear distortion can be reduced as described above.

The auxiliary circuit described above may be a 90° hybrid 17. The 90° hybrid 17 is in communication with the fifth port (port 17a), the sixth port (port 17b), the seventh port (port 17c), which is in communication with the ports 17a and 17b, and the ports 17a and 17b. It has an eighth port (port 17d). The port 17c is a port to which a signal whose phase is shifted by 90 degrees from the phase of the signal distributed from the port 17b to the port 17d is distributed from the port 17b. Port 17b may be connected to the first terminal (transmission terminal 7). Port 17c may be connected to a first filter (transmission filter 13A). Port 17d may be connected to a second filter (transmission filter 13B).

In this case, the auxiliary circuit can be realized using, for example, a known 90° hybrid 17. As a result, for example, it is possible to obtain the effect of cost reduction by using general-purpose products. Further, for example, it is possible to obtain the benefits of improved characteristics pursued in conventional 90° hybrids.

The transmission filter system 2T may include a terminating resistor connected to the fifth port (port 17a) of the 90° hybrid 17.

In this case, for example, reflection loss in the transmission filter system 2T can be reduced. From another point of view, the voltage standing wave ratio (VSWR) at the transmission terminal 7 can be reduced (theoretically, it can be reduced to the minimum value of 1). Specifically, it is as follows. As described with reference to FIG. 3(a), the signal input to the transmission terminal 7 is distributed by the 90° hybrid 17 to the transmission filters 13A and 13B. The signal reflected by the transmission filter 13A and flowing from the port 17c to the port 17b (from another perspective, the transmission terminal 7) has a phase difference of 180° with respect to the signal input to the transmission terminal 7 by the 90° hybrid 17. It is said to be a signal that On the other hand, the signal reflected by the transmission filter 13B and flowing from the port 17d to the port 17b maintains the same phase as the signal input to the transmission terminal 7. Therefore, the two cancel each other out. That is, the signal input to the transmission terminal 7 does not return to the transmission terminal 7 even if a portion thereof is reflected by the transmission filters 13A and 13B. Further, the signal reflected by the transmission filter 13A and flowing from the port 17c to the port 17a (from another point of view, the terminating resistor 23) has a phase difference of 90° with respect to the signal input to the transmission terminal 7 by the 90° hybrid 17. It is said that the signal has On the other hand, the signal reflected by the transmission filter 13B and flowing from the port 17d to the port 17a is also converted into a signal having a phase difference of 90° with respect to the signal input to the transmission terminal 7 by the 90° hybrid 17. There is. Therefore, these two signals are combined and input to the termination resistor 23. As described above, theoretically, all reflected waves are input to the terminating resistor 23. Therefore, by appropriately setting the impedance of the terminating resistor 23, the reflected waves returning to the transmission terminal 7 can be reduced (in theory, eliminated), and the VSWR at the transmission terminal 7 can be reduced. From another point of view, the need to improve the impedance matching of the transmission filters 13A and 13B is reduced, and the degree of freedom in designing the transmission filters 13A and 13B is improved.

Note that in the first embodiment described above, the duplexer 1 is an example of a composite filter. The antenna terminal 5 is an example of a common terminal. The transmission terminal 7 is an example of a first terminal. The receiving terminal 9 is an example of a second terminal. The transmission filter system 2T is an example of a first filter system. The reception filter system 2R is an example of a second filter system. The transmission filter 13A is an example of a first filter. The transmission filter 13B is an example of a second filter. The reception filter 15 is an example of a third filter. The transmission band is an example of a first passband. The reception band is an example of the second passband. Port 21b is an example of a first port. Port 21a is an example of a second port. Port 21c is an example of a third port. Port 21d is an example of a fourth port. The 90° hybrid 17 is an example of an auxiliary circuit. The port 17a is an example of the fifth port according to the fourth aspect. The port 17b is an example of the sixth port according to the fourth aspect. The port 17c is an example of the seventh port according to the fourth aspect. The port 17d is an example of the eighth port according to the fourth aspect.

<Second embodiment>
(Configuration of duplexer)
FIG. 4 is a circuit diagram showing the configuration of a duplexer 201 as a composite filter according to the second embodiment.

Simply put, the duplexer 201 has a configuration in which the transmission filter 13 and the reception filter 15 are replaced in the duplexer 1 of the first embodiment. Specifically, it is as follows.

The reception filter system 202R includes, in order from the antenna terminal 5 to the reception terminal 9, a 180° hybrid 21, a phase shifter 19, and two reception filters 15A and 15B (hereinafter, without distinguishing between the two or collectively, ), a 90° hybrid 17, and a terminating resistor 23. Regarding these connection relationships, the description of the connection relationships in the transmission filter system 2T in the first embodiment may be used. However, the word transmission filters 13A and 13B (13) is replaced with the word reception filters 15A and 15B (15), and the word transmission terminal 7 is replaced with the word reception terminal 9.

The two reception filters 15 correspond to the same pass band (however, unlike the first embodiment, the reception band), like the two transmission filters 13 in the first embodiment. Regarding the fact that the configurations and characteristics of the two reception filters 15 may be the same, the description of the two transmission filters 13 in the first embodiment may be used.

The transmission filter system 202T includes a transmission filter 13 and a 180° hybrid 21 in order from the transmission terminal 7 to the antenna terminal 5. Regarding these connection relationships, the description of the connection relationships in the reception filter system 2R in the first embodiment may be used. However, the word reception filter 15 is replaced with the word transmission filter 13, and the word reception terminal 9 is replaced with the word transmission terminal 7.

(Operation of duplexer)
The operation of the duplexer 201 is as follows.

First, the operation of the duplexer 1 when a signal (for example, a transmission signal) is input to the transmission terminal 7 will be explained. In the following description, the phase of the signal flowing through the transmission terminal 7 is assumed to be 0°.

The signal input from the transmission terminal 7 to the port 21d of the 180° hybrid 21 via the transmission filter 13 is divided into a 0° phase signal output from the port 21a and a 180° phase signal output from the port 21c. distributed to. Either signal is reflected by receive filter 15A or 15B and returns to port 21a or 21c. Among these, the signal with a phase of 0° outputted from the port 21a returns to the port 21a while maintaining the phase of 0°. A signal with a phase of 180° outputted from the port 21c is returned to a phase of 0° by reciprocating through the phase shifter 19 and returns to the port 21c. Therefore, two signals of the same phase are input to the ports 21a and 21c.

The two signals that are distributed from the two signals input to ports 21a and 21c and flow to port 21b maintain the same phase. Therefore, both are combined and output to the antenna terminal 5. On the other hand, the two signals that are distributed from the two signals input to the ports 21a and 21c and flow to the port 21d are made to have opposite phases by shifting the phase of one of them by 180 degrees. As a result, the two cancel each other out. That is, the signal input from the transmission filter 13 to the 180° hybrid 21 does not return to the transmission filter 13.

As described above, the signal input from the transmission terminal 7 is output to the antenna terminal 5, but is not output to the reception filter 15 (reception terminal 9). For convenience of explanation, it was expressed as two signals input to ports 21a and 21c being distributed and flowing to port 21d, but the fact that no signal is output from port 21d means that the signal is not actually distributed to port 21d. That means no. That is, if insertion loss is ignored, the strength of the signal output from the antenna terminal 5 is the same as the strength of the signal input to the transmission terminal 7.

Next, the operation of the duplexer 1 when a signal (for example, a received signal) is input to the antenna terminal 5 will be described. In the following description, the phase of the signal flowing through the antenna terminal 5 is assumed to be 0°.

A signal input from the antenna terminal 5 to the port 21b of the 180° hybrid 21 is distributed to ports 21a and 21c. The signal output from the port 21a is input to the 90° hybrid port 17c via the reception filter 15A while maintaining the phase of 0°. The signal output from the port 21c is input into the 90° hybrid port 17d via the reception filter 15B with its phase shifted by 90° by the phase shifter 19.

The phase of the signal distributed to port 17b (receiving terminal 9) is shifted by 90° from the signal with phase 0° input to port 17c. The phase of the signal distributed to port 17b from the 90° phase signal input to port 17d is maintained at 90°. Therefore, both are combined and output from the port 17b to the receiving terminal 9. On the other hand, the phase of the signal distributed to the port 17a from the 0° phase signal input to the port 17c is maintained at 0°. The signal distributed to port 17a from the 90° phase signal input to port 17d is shifted in phase by 90° to become a 180° phase signal. Therefore, the two cancel each other out and are not output from port 17a.

As described above, the signal input from the antenna terminal 5 is output to the reception filter 15 (reception terminal 9), but is not output to the transmission terminal 7. Also, for convenience of explanation, it has been expressed that a signal input to port 17c or 17d is distributed to port 17a, but the fact that no signal is output from port 17a means that no signal is actually distributed to port 17a. That's what it means. That is, if insertion loss is ignored, the strength of the signal output to the receiving terminal 9 is the same as the strength of the signal input to the antenna terminal 5.

Next, the operation of the duplexer 1 when two signals are input to the transmission terminal 7 and nonlinear distortion occurs in the transmission filter 13 will be described. In the following description, it is assumed that the nonlinear distortion has a frequency within the reception band of the reception filter 15 and passes through the reception filter 15 without being reflected by the reception filter 15. Further, the phase of nonlinear distortion when flowing from the transmission filter 13 to the port 21d is assumed to be 0°.

The nonlinear distortion input from the transmission filter 13 to the port 21d of the 180° hybrid 21 is divided into 0° phase nonlinear distortion output from the port 21a and 180° phase nonlinear distortion output from the port 21c. . The nonlinear distortion output from the port 21a is input to the 90° hybrid port 17c via the reception filter 15A while maintaining the phase of 0°. The phase of the nonlinear distortion outputted from the port 21c is shifted by 90° by the phase shifter 19 to produce nonlinear distortion with a phase of 270°, and the nonlinear distortion is inputted to the port 17d of the 90° hybrid via the reception filter 15B.

The phase of the nonlinear distortion distributed to the port 17b (receiving terminal 9) is shifted by 90° from the nonlinear distortion with a phase of 0° inputted to the port 17c. The phase of the signal distributed to port 17b from the 270° phase signal input to port 17d is maintained at 270°. Therefore, the above two signals are in opposite phases to each other, cancel each other out, and are not output from the port 17b. That is, nonlinear distortion is not input to the receiving terminal 9. On the other hand, the phase of the signal distributed to the port 17a from the 0° phase signal input to the port 17c is maintained at 0°. The signal distributed to port 17a from the 270° phase signal input to port 17d is shifted in phase by 90° to become a 360° phase signal. Therefore, the above two signals are in phase with each other, and are combined and input to the termination resistor 23 from the port 17a. Note that in this embodiment, since the transmission signal is reflected by the reception filter 15, a strong transmission signal is also applied to the reception filter 15. Therefore, nonlinear distortion also occurs in the reception filter 15. However, the phase relationship of the nonlinear distortion generated in the reception filter 15A and the reception filter 15B is the same as that of the nonlinear distortion generated in the transmission filter 13 described above and propagated to the reception filter 15. The distortion is absorbed by the terminating resistor 23 and is not input to the receiving terminal 9.

As described above, in this embodiment, the composite filter (brancher 201) has a common terminal (antenna terminal 5), a first terminal (reception terminal 9), a second terminal (transmission terminal 7), and an antenna terminal. 5 and the reception terminal 9, and a second filter system (transmission filter system 202T) that connects the antenna terminal 5 and the transmission terminal 7. are doing. The reception filter system 202R and the transmission filter system 202T share the 180° hybrid 21 connected to the antenna terminal 5. The 180° hybrid 21 includes a first port (port 21b), a second and third ports (ports 21a and 21c) that are electrically connected to the port 21b, and a fourth port (ports 21a and 21c) that are electrically electrically connected to the ports 21a and 21c. It has a port 21d). Port 21a and port 21c are ports to which signals having the same phase are distributed from port 21b. The port 21d is a port to which a signal whose phase is shifted by 180 degrees from the phase of the signal distributed from the port 21c to the port 21b is distributed from the port 21c. Port 21b is connected to antenna terminal 5. The reception filter system 202R includes a first filter (reception filter 15A), a 90° phase shifter 19, a second filter (reception filter 15B), and an auxiliary circuit (90° hybrid 17). The reception filter 15A is connected to the port 21a and corresponds to the first passband (reception band). Phase shifter 19 is connected to port 21c. The reception filter 15B is connected to the port 21c via the phase shifter 19, and corresponds to the reception band. The 90° hybrid 17 connects the reception filters 15A and 15B to the reception terminal 9, and changes the phase of the signal flowing between the reception terminal 9 and the reception filter 15A to the signal flowing between the reception terminal 9 and the reception filter 15B. shifted by 90° with respect to the phase of The transmission filter system 202T includes a transmission filter 13. The transmission filter 13 corresponds to a second pass band (transmission band) different from the reception band, and connects the port 21d and the transmission terminal 7.

Therefore, as understood from the above-described operation, the same or similar effects as in the first embodiment are achieved. For example, nonlinear distortion having a frequency within the reception band generated in the transmission filter 13 is distributed to the two reception filters 15A and 15B, and then canceled out in the 90° hybrid. That is, the nonlinear distortion input to the reception terminal 9 is reduced (theoretically eliminated). As a result, the receiving sensitivity of the duplexer 1 is improved.

Note that in the second embodiment described above, the duplexer 201 is an example of a composite filter. The antenna terminal 5 is an example of a common terminal. The receiving terminal 9 is an example of a first terminal. The transmission terminal 7 is an example of a second terminal. The reception filter system 202R is an example of a first filter system. The transmission filter system 202T is an example of a second filter system. The reception filter 15A is an example of a first filter. The reception filter 15B is an example of a second filter. The transmission filter 13 is an example of a third filter. The reception band is an example of the first passband. The transmission band is an example of a second pass band. Further, similarly to the first embodiment, the various ports are examples of the first to eighth ports.

<Third embodiment>
FIG. 5 is a circuit diagram showing the configuration of a duplexer 301 as a composite filter according to the third embodiment.

The duplexer 301 differs from the duplexer 1 of the first embodiment only in the configuration of the auxiliary circuit of the transmission filter system. Specifically, the transmission filter system 302T of the duplexer 301 includes an auxiliary circuit 317 instead of the 90° hybrid 17 of the first embodiment. The auxiliary circuit 317 includes a divider 25 and a 90° phase shifter 27 (hereinafter sometimes simply referred to as "phase shifter 27").

The divider 25 has, for example, a port 25a and ports 25b and 25c that are electrically connected to the port 25a. Divider 25 distributes the signal input to port 25a to ports 25b and 25c. The distribution ratio at this time is 1:1. The divider 25 may have a function as a combiner that combines signals input to the ports 25b and 25c and outputs the combined signal from the port 25a. The structure of the divider 25 may be a known structure or an application of a known structure. For example, the divider 25 may be of a distributed constant type or a lumped constant type.

The phase shifter 27 shifts the phase of the input signal by 90 degrees and outputs the signal. The configuration of the phase shifter 27 may be a known configuration or an application of a known configuration. For example, the phase shifter 27 may be of a distributed constant type or a lumped constant type. Further, may have the same configuration as the phase shifter 19 described above, or may have a different configuration.

The transmitting terminal 7 is connected to the port 25a of the divider 25. A phase shifter 27 is connected to the port 25b, and from another point of view, a transmission filter 13A is connected via the phase shifter 27. A transmission filter 13B is connected to the port 25c.

The operation of the auxiliary circuit 317 is similar to that of the 90° hybrid 17, except for the fact that the port 17a to which the terminating resistor 23 is connected is not provided. Therefore, for example, the description of the operation of the 90° hybrid 17 in the first embodiment is similar to that of the auxiliary circuit 317, except that in the 90° hybrid 17, signals input to ports 17c and 17d are distributed to port 17a. May be used to assist in operations. However, the word for port 17b is replaced by the word for port 25a, and the word for port 17d is replaced by the word for port 25c. Further, the port connected to the transmission filter 13A of the auxiliary circuit 317 (phase shifter 27) is set to port 27a, and the word port 17c is replaced with the word port 27a.

As understood from the above description, the operation of the duplexer 301 as a whole is also roughly the same as the operation of the duplexer 1 as a whole in the first embodiment. Therefore, in this embodiment as well, the same effects as in the first embodiment can be obtained. For example, nonlinear distortion is reduced, isolation is improved, and electrical resistance is improved.

<Fourth embodiment>
FIG. 12 is a circuit diagram showing the configuration of a duplexer 401 as a composite filter according to the fourth embodiment.

The duplexer 401 differs from the duplexer 1 of the first embodiment only in the configuration of the auxiliary circuit of the transmission filter system. Specifically, the transmission filter system 402T of the duplexer 401 includes an auxiliary circuit 417 instead of the 90° hybrid 17 of the first embodiment. The auxiliary circuit 417 includes the 180° hybrid 22 and the 90° phase shifter 27 described in the third embodiment.

The 180° hybrid 22 is basically similar to the 180° hybrid 21. Therefore, the description regarding the configuration and operation of the 180° hybrid 21 may be applied to the 180° hybrid 22 unless there is a contradiction. At this time, the word for port 21a is replaced by the word for port 22a, the word for port 21b is replaced by the word for port 22b, the word for port 21c is replaced by the word for port 22c, and the word for port 21d is replaced by the word for port 22d. The 180° hybrids 21 and 22 included in one duplexer 401 may have the same or different specific configurations (structure, dimensions, etc.).

A transmission filter 13A is connected to the port 22a via a phase shifter 27. A transmission terminal 7 is connected to the port 22b. A transmission filter 13B is connected to the port 22c. The terminating resistor 23 described in the first embodiment is connected to the port 22d.

The operation of the auxiliary circuit 417 is similar to the operation of the 90° hybrid 17 of the first embodiment. Specifically, it is as follows.

As can be understood from the connections with the transmission terminal 7, the transmission filters 13A and 13B, and the terminating resistor 23, the port 22b is connected to the port 17b of the first embodiment, the port 22d is connected to the port 17a of the first embodiment, and the phase shifter The port 27a of No. 27 corresponds to the port 17c of the first embodiment, and the port 22c corresponds to the port 17d of the first embodiment. As understood from the operations of the 180° hybrid and phase shifter described above, the distribution, combination, and phase of signals between the four ports are basically handled by the 90° hybrid 17 and the auxiliary circuit 417. The same is true.

The difference is the absolute value of the phase of the distributed signal and the combined signal. For example, the signals after distribution (for example, signal s1-0 in FIG. 2(a) and signal s4-0 in FIG. 2(d)), which have been explained as having a phase of 0° for convenience, are Assume that the phase difference with the previous signals (s1 and s4) is zero. At this time, between the three ports connected to the transmission terminal 7 and the transmission filters 13A and 13B, the phase of the signal distributed in the auxiliary circuit 417 and the phase of the signal distributed in the 90° hybrid 17 are It's the same. On the other hand, between the three ports connected to the termination resistor 23 and the transmission filters 13A and 13B, the phase of the signal distributed in the auxiliary circuit 417 is 90° higher than the phase of the signal distributed in the hybrid 17. big. However, as described in the description of the 90° hybrid 17, the phase difference between the two signals after distribution is the essence of the hybrid, and the phase difference before and after distribution is not an essential difference.

As understood from the above description, the operation of the duplexer 401 as a whole is generally similar to the operation of the duplexer 1 as a whole in the first embodiment. Therefore, in this embodiment as well, the same effects as in the first embodiment can be obtained. For example, nonlinear distortion is reduced, isolation is improved, and electrical resistance is improved.

In addition, in the above fourth embodiment, the 180° hybrid 22 is an example of the second 180° hybrid according to claim 5. The port 22b is an example of the fifth port according to the fifth aspect. The port 22a is an example of the sixth port according to the fifth aspect. The port 22c is an example of the seventh port according to the fifth aspect. The port 22d is an example of the eighth port according to the fifth aspect. The phase shifter 27 is an example of the second phase shifter according to claim 5.

<Fifth embodiment>
FIG. 13 is a circuit diagram showing the configuration of a duplexer 501 as a composite filter according to the fifth embodiment.

The duplexer 501 differs from the duplexer 1 of the first embodiment only in the configuration of the auxiliary circuit of the transmission filter system. Specifically, the transmission filter system 502T of the duplexer 501 includes an auxiliary circuit 517 instead of the 90° hybrid 17 of the first embodiment. The auxiliary circuit 517 includes a 180° hybrid 24 and a 90° phase shifter 27, as in the fourth embodiment. However, these specific connection positions are different from those in the fourth embodiment.

The 180° hybrid 24 is basically similar to the 180° hybrid 21. Therefore, the description regarding the configuration and operation of the 180° hybrid 21 may be applied to the 180° hybrid 24 unless there is a contradiction. At this time, the word for port 21a is replaced by the word for port 24c, the word for port 21b is replaced by the word for port 24d, the word for port 21c is replaced by the word for port 24a, and the word for port 21d is replaced by the word for port 24b. The 180° hybrids 21 and 24 included in one duplexer 501 may have the same or different specific configurations (structure, dimensions, etc.).

A transmission filter 13A is connected to the port 24a. The transmission terminal 7 is connected to the port 24b. A transmission filter 13B is connected to the port 24c via a phase shifter 27. A terminating resistor 23 is connected to the port 24d.

The operation of the auxiliary circuit 517 is similar to the operation of the 90° hybrid 17 of the first embodiment. Specifically, it is as follows.

As can be understood from the connection with the transmission terminal 7, the transmission filters 13A and 13B, and the terminating resistor 23, the port 24b is connected to the port 17b of the first embodiment, the port 24d is connected to the port 17a of the first embodiment, and the phase shifter The port 27a of No. 27 corresponds to the port 17d of the first embodiment, and the port 24a corresponds to the port 17c of the first embodiment. As understood from the operations of the 180° hybrid and phase shifter described above, the distribution, combination, and phase of signals between the four ports are basically handled by the 90° hybrid 17 and the auxiliary circuit 517. The same is true.

The difference, like the fourth embodiment, is the absolute value of the phase of the distributed signal and the combined signal. However, contrary to the fourth embodiment, the phase of the signal distributed in the auxiliary circuit 417 is distributed in the 90° hybrid 17 between the three ports connected to the transmission terminal 7 and the transmission filters 13A and 13B. is larger than the phase of the signal. Between the three ports connected to the terminating resistor 23 and the transmission filters 13A and 13B, the phase of the signal distributed in the auxiliary circuit 417 and the phase of the signal distributed in the 90° hybrid 17 are the same. As mentioned above, this is not an essential difference.

As understood from the above description, the operation of the duplexer 501 as a whole is also roughly the same as the operation of the duplexer 1 as a whole in the first embodiment. Therefore, in this embodiment as well, the same effects as in the first embodiment can be obtained. For example, nonlinear distortion is reduced, isolation is improved, and electrical resistance is improved.

In addition, in the above fifth embodiment, the 180° hybrid 22 is an example of the second 180° hybrid according to claim 6. The port 24b is an example of the fifth port according to claim 6. The port 24a is an example of the sixth port according to claim 6. The port 24c is an example of the seventh port according to the sixth aspect. The port 24d is an example of the eighth port according to claim 6. The phase shifter 27 is an example of the second phase shifter according to claim 6.

<Other embodiments>
As understood from the duplexer 201 of the second embodiment, in the duplexer 1 of the first embodiment, the transmission filter 13 and the reception filter 15 may be replaced. Similarly, although not particularly shown, in the duplexer 301 of the third embodiment, the duplexer 401 of the fourth embodiment, and the duplexer 501 of the fifth embodiment, the transmission filter 13 and the reception filter 15 are replaced. It's okay to be rejected.

<Example of configuration of elements in the duplexer and example of use of the duplexer>
Below, examples of the configuration of elements in the duplexer and usage examples of the duplexer according to the embodiment are shown. The configuration examples, usage examples, etc. described below may be applied to any of the embodiments described above unless otherwise specified. However, for convenience, the reference numeral of the duplexer of any one embodiment may be used to represent the duplexer according to a plurality of embodiments.

(Example of elastic wave filter)
As described above, the transmission filter 13 and/or the reception filter 15 may be an elastic wave filter using elastic waves. An example of the configuration of an elastic wave filter will be shown below.

(Example of elastic wave element)
FIG. 6 is a plan view schematically showing the configuration of an elastic wave resonator 29 (hereinafter sometimes simply referred to as "resonator 29") as an example of an elastic wave element included in an elastic wave filter. In addition, in the following description, the word resonator 29 may be replaced with the word acoustic wave element unless a contradiction arises.

Although the resonator 29 may be oriented either upward or downward, in the following, for convenience, an orthogonal coordinate system consisting of the D1 axis, D2 axis, and D3 axis is attached to the drawing, and the D3 axis is Terms such as upper surface or lower surface may be used with the positive side of the surface as the upper side. Note that the D1 axis is defined to be parallel to the propagation direction of an elastic wave propagating along the top surface of the piezoelectric body, which will be described later, and the D2 axis is defined to be parallel to the top surface of the piezoelectric body and orthogonal to the D1 axis. The D3 axis is defined to be orthogonal to the top surface of the piezoelectric body.

The resonator 29 is constituted by a so-called one-port acoustic wave resonator. For example, the resonator 29 outputs a signal input from one of the two terminals 28 schematically shown on both sides of the paper from the other of the two terminals 28. At this time, the resonator 29 converts an electric signal into an elastic wave, and converts an elastic wave into an electric signal. As will be understood from the description of FIG. 7 described below, the terminal 28 may correspond to, for example, any one of the antenna terminal 5, the transmission terminal 7, the reception terminal 9, and the reference potential section 11 (described later).

The resonator 29 includes, for example, a substrate 31 (at least a part of the upper surface 31a side thereof), an excitation electrode 33 located on the upper surface 31a, and a pair of reflectors 35 located on both sides of the excitation electrode 33. There is. A plurality of resonators 29 may be configured on one substrate 31. That is, the substrate 31 may be shared by a plurality of resonators 29. In the following description, in order to distinguish between a plurality of resonators 29 that share the same substrate 31, for convenience, the combination of an excitation electrode 33 and a pair of reflectors 35 (electrode portions of the resonator 29) will be referred to as the resonator 29. (as if the resonator 29 does not include the substrate 31).

The substrate 31 has piezoelectricity at least in the region of the upper surface 31a where the resonator 29 is provided. An example of such a substrate 31 is one in which the entire substrate is made of a piezoelectric material (that is, a piezoelectric substrate). Further, for example, a so-called bonded substrate can be mentioned. A bonded substrate is a substrate made of a piezoelectric material having an upper surface 31a (piezoelectric substrate) and a surface of the piezoelectric substrate opposite to the upper surface 31a, which is directly attached with or without an adhesive. and a mated support substrate. The support substrate may or may not have a cavity below the piezoelectric substrate. Further, as for the substrate 31 having piezoelectricity in the region where the resonator 29 is provided, for example, the support substrate and a part of the main surface on the +D3 side of the support substrate or the entire main surface are made of piezoelectric material. Examples include those in which a film (piezoelectric film) or a multilayer film including a piezoelectric film is formed.

The piezoelectric body 31b constituting at least the region of the substrate 31 where the resonator 29 is provided is made of, for example, a piezoelectric single crystal. Examples of materials constituting such a single crystal include lithium tantalate (LiTaO ₃ ), lithium niobate (LiNbO ₃ ), and quartz (SiO ₂ ). The cut angle, planar shape, and various dimensions may be set appropriately.

The excitation electrode 33 and the reflector 35 are composed of a layered conductor provided on the substrate 31. The excitation electrode 33 and the reflector 35 are, for example, made of the same material and thickness. The layered conductors constituting these are, for example, metal. The metal is, for example, Al or an alloy containing Al as a main component (Al alloy). The Al alloy is, for example, an Al-Cu alloy. The layered conductor may be composed of multiple metal layers. The thickness of the layered conductor is appropriately set depending on the electrical characteristics required of the resonator 29 and the like. As an example, the thickness of the layered conductor is 50 nm or more and 600 nm or less.

The excitation electrode 33 is constituted by a so-called IDT (Interdigital Transducer) electrode, and has a pair of comb-teeth electrodes 37 (one is hatched for convenience to improve visibility). Each comb-teeth electrode 37 includes, for example, a busbar 39, a plurality of electrode fingers 41 extending in parallel from the busbar 39, and a plurality of dummy electrodes 43 protruding from the busbar 39 between the plurality of electrode fingers 41. There is. The pair of comb-teeth electrodes 37 are arranged so that the plurality of electrode fingers 41 interlock with each other (cross each other).

The bus bar 39 is, for example, formed in an elongated shape that has a substantially constant width and extends linearly in the propagation direction of the elastic wave (direction D1). The pair of bus bars 39 are opposed to each other in a direction (direction D2) orthogonal to the propagation direction of elastic waves. Note that the bus bar 39 may have a width that changes or may be inclined with respect to the propagation direction of the elastic wave.

Each electrode finger 41 is, for example, formed in an elongated shape that has a substantially constant width and extends linearly in a direction (direction D2) orthogonal to the propagation direction of elastic waves. Note that the electrode fingers 41 may have varying widths. In each comb-teeth electrode 37, the plurality of electrode fingers 41 are arranged in the propagation direction of the elastic wave. Moreover, the plurality of electrode fingers 41 of one comb-teeth electrode 37 and the plurality of electrode fingers 41 of the other comb-teeth electrode 37 are basically arranged alternately.

The pitch p of the plurality of electrode fingers 41 (for example, the distance between the centers of two adjacent electrode fingers 41) is basically constant within the excitation electrode 33. Note that the excitation electrode 33 may have a part that is unique with respect to the pitch p. Specific areas include, for example, a narrow pitch area where the pitch p is narrower than the majority (for example, 80% or more), a wide pitch area where the pitch p is wider than the majority, and a small number of electrode fingers 41 that are substantially spaced apart. An example is the thinned out part.

In the following, unless otherwise specified, pitch p refers to the pitch of a portion (most of the plurality of electrode fingers 41) excluding the unique portions as described above. In addition, in cases where the pitch of most of the plurality of electrode fingers 41 excluding peculiar parts is changing, the average value of the pitches of most of the plurality of electrode fingers 41 is used as the value of pitch p. May be used.

The number of electrode fingers 41 may be appropriately set depending on the electrical characteristics required of the resonator 29 and the like. Since FIG. 6 is a schematic diagram, the number of electrode fingers 41 is shown to be small. In reality, more electrode fingers 41 than shown may be arranged. The same applies to the strip electrode 47 of the reflector 35, which will be described later.

The lengths of the plurality of electrode fingers 41 are, for example, equal to each other. Note that the excitation electrode 33 may be subjected to so-called apodization, in which the length of the plurality of electrode fingers 41 (from another point of view, the intersection width W) changes depending on the position in the propagation direction. The length and width of the electrode fingers 41 may be set as appropriate depending on required electrical characteristics and the like.

The dummy electrode 43 has, for example, a substantially constant width and protrudes in a direction perpendicular to the propagation direction of the elastic wave. Its width is, for example, equivalent to the width of the electrode finger 41. Further, the plurality of dummy electrodes 43 are arranged at the same pitch as the plurality of electrode fingers 41, and the tip of the dummy electrode 43 of one comb-teeth electrode 37 is the tip of the electrode finger 41 of the other comb-teeth electrode 37. and are facing each other through a gap. Note that the excitation electrode 33 may not include the dummy electrode 43.

The pair of reflectors 35 are located on both sides of the excitation electrode 33 in the propagation direction of the elastic wave. For example, each reflector 35 may be electrically floating or may be provided with a reference potential. Each reflector 35 is formed, for example, in a lattice shape. That is, the reflector 35 includes a pair of bus bars 45 facing each other and a plurality of strip electrodes 47 extending between the pair of bus bars 45. The pitch between the plurality of strip electrodes 47 and the pitch between adjacent electrode fingers 41 and strip electrodes 47 are basically equivalent to the pitch between the plurality of electrode fingers 41.

When a voltage is applied to the pair of comb-teeth electrodes 37, the voltage is applied to the piezoelectric upper surface 31a by the plurality of electrode fingers 41, and the upper surface 31a vibrates. This excites an elastic wave (for example, SAW) that propagates in the D1 direction. The elastic waves are reflected by the plurality of electrode fingers 41. Then, a standing wave is created in which the pitch p of the plurality of electrode fingers 41 is approximately half a wavelength (λ/2). Electric signals generated in the piezoelectric body 31b by the standing waves are extracted by the plurality of electrode fingers 41. Based on this principle, the resonator 29 functions as a resonator whose resonant frequency is the frequency of an elastic wave whose pitch p is a half wavelength.

Although not particularly shown, the resonator 29 may have a protective film (not shown) that covers the upper surface 31a of the substrate 31 from above the excitation electrode 33 and the reflector 35. Such a protective film is made of an insulating material such as SiO ₂ , for example, and reduces the possibility that the excitation electrode 33 etc. will corrode, and/or compensates for changes in characteristics due to temperature changes of the resonator 29. Contribute to things. Furthermore, the resonator 29 may have an additional film that overlaps the upper or lower surface of the excitation electrode 33 and the reflector 35 and has a shape that basically fits within the excitation electrode 33 and the reflector 35 when seen in plan view. good. Such an additional film is made of, for example, an insulating material or a metal material that has different acoustic characteristics from the material of the excitation electrode 33, etc., and contributes to improving the reflection coefficient of elastic waves.

A typical configuration example of one resonator 29 has one excitation electrode 33, as described above. However, one resonator 29 may have a plurality of excitation electrodes 33 connected in series. In other words, one resonator 29 may be divided into a plurality of parts. In this case, for example, the voltage applied to the resonator 29 is distributed to the plurality of excitation electrodes 33, so that the electric resistance of the resonator 29 is improved. Furthermore, since the vibrations of the elastic waves are reduced, nonlinear distortion is reduced.

(Example of configuration of duplexer body using elastic wave filter)
FIG. 7 is a circuit diagram schematically showing the configuration of the duplexer main body 3 (a portion that includes the transmission filter 13 and the reception filter 15 and directly contributes to filtering). In this figure, only the duplexer main body 3 and terminals of the duplexer 1 are shown. That is, illustration of the 90° hybrid 17, phase shifter 19, 180° hybrid 21, etc. is omitted. Further, only one of the transmission filters 13A and 13B is shown.

As can be understood from the reference numeral shown at the upper left of the drawing, the comb-teeth electrode 37 is schematically shown in the form of a two-pronged fork, and the reflector 35 is a single line with bent ends. It is expressed as. In the following description, the term duplexer main body 3 may be replaced with the term duplexer 1 as long as there is no contradiction.

The duplexer main body 3 has the antenna terminal 5, the transmission terminal 7, the reception terminal 9, the transmission filter 13, and the reception filter 15, as described above. Further, the duplexer main body 3 has a reference potential section 11. The reference potential part 11 is a part (conductor) to which a reference potential is applied, and more specifically, it may be a terminal to which a reference potential is applied, or a structure other than the terminal (for example, a shield). You can.

The antenna terminal 5 and the filters (13 and 15) are connected via a 180° hybrid 21 or the like. In FIG. 7, for convenience, the 180° hybrid 21 and the like are omitted, and the connection between the antenna terminal 5 and the filter is shown by dotted lines. Further, the transmission terminal 7 and the transmission filter 13 are connected via a 90° hybrid 21. In the following description, for convenience, the connection relationship may be described as if the 180° hybrid 21, 90° hybrid 21, etc. are not provided.

In FIG. 7, unlike FIG. 1, two receiving terminals 9 are depicted. In the configuration illustrated in FIG. 7, this corresponds to the reception filter 15 outputting a balanced signal containing two signals whose phases are opposite to each other. However, the reception filter 15 may output an unbalanced signal consisting of one signal whose signal level changes with respect to the reference potential (the number of reception terminals 9 may be one). . It is clear that two reception terminals 9 can be applied to the duplexer 1 of the first embodiment. In the duplexer 201 of the second embodiment, two reception terminals 9 are applied, for example, by providing a 90° hybrid 17 for each reception terminal 9 (two 90° hybrids 17 are provided in total). good.

The transmission filter 13 is configured by, for example, a ladder type filter in which a plurality of resonators 29 (29S and 29P) are connected in a ladder type. That is, the transmission filter 13 includes a plurality of (or one) series resonators 29S connected in series between the transmission terminal 7 and the antenna terminal 5, the series line (series arm), and the reference potential section 11. It has a plurality of (or even one) parallel resonators 29P (parallel arms) that connect the two.

The reception filter 15 includes, for example, a resonator 29 and a multimode filter 49 (including a double mode filter. Hereinafter, it may be referred to as the MM filter 49). The MM filter 49 includes a plurality of (three in the illustrated example) excitation electrodes 33 arranged in the propagation direction of elastic waves, and a pair of reflectors 35 disposed on both sides of the excitation electrodes 33.

Note that the configurations of the transmission filter 13 and reception filter 15 described above are merely examples, and may be modified as appropriate. For example, the reception filter 15 may be configured by a ladder filter like the transmission filter 13, or conversely, the transmission filter 13 may include the MM filter 49.

In the above configuration, each of the plurality of resonators 29 (29S, 29P and the resonator 29 of the reception filter 15) and the MM filter 49 can be said to be an elastic wave element. These plurality of acoustic wave elements may be provided on one substrate 31, or may be provided in a distributed manner on two or more substrates 31. For example, the plurality of resonators 29 configuring the transmission filter 13 may be provided on the same substrate 31. Similarly, the resonator 29 and the MM filter 49 that constitute the reception filter 15 may be provided on the same substrate 31. The transmission filters 13A and 13B may be provided on the same substrate 31 or may be provided on different substrates 31. Similarly, the reception filters 15A and 15B may be provided on the same substrate 31 or may be provided on different substrates 31. The transmission filter 13 (one or two) and the reception filter 15 (one or two) may be provided on the same substrate 31 or may be provided on mutually different substrates 31. Regarding one filter, a plurality of series resonators 29S may be provided on the same substrate 31, and a plurality of parallel resonators 29P may be provided on another same substrate 31.

(Example of sharing a substrate with acoustic wave elements)
As described above, a plurality of elastic wave elements (such as the elastic wave resonator 29) may be appropriately arranged on one or more substrates 31. An example is shown below.

FIG. 8 is a plan view showing an example of the chip 51 included in the duplexer main body 3. As understood from the orthogonal coordinate system D1-D2-D3, this figure shows the top surface 31a of the substrate 31. Furthermore, in this figure, the resonators 29 (29S and 29P) are schematically represented by rectangles.

The chip 51 has transmitting filters 13A and 13B, which are ladder type filters, on the same substrate 31. Furthermore, the chip 51 has a plurality of terminals (53I, 53O, 53G, and 53E) that are electrically connected to the circuit board on which the chip 51 is mounted. The two terminals 53I are terminals into which transmission signals are input. For example, in the duplexer 1, the two terminals 53I are connected to the transmission terminal 7 via the ports 17c and 17d of the 90° hybrid 17. The two terminals 53O are terminals that output filtered transmission signals. For example, in the duplexer 1, one terminal 53O is connected to the port 21a of the 180° hybrid 21, and the other terminal 53O is connected to the port 21c of the 180° hybrid 21 via the phase shifter 19. A plurality of (three in the illustrated example) terminals 53G are terminals to which a reference potential is applied. The terminal 53E will be described later.

The transmission filters 13A and 13B may have substantially the same configuration as described above. For example, the transmission filters 13A and 13B may have the same number of series resonators 29S and parallel resonators 29P, and the corresponding resonators 29 may have the same configuration. The resonators 29 having the same configuration may have the same electrode portions (the excitation electrode 33 and the reflector 35) in the shape, size, material, orientation with respect to the crystal orientation of the substrate 31, etc., for example. However, parts that are not essential to the filters may be different between the transmission filters 13A and 13B. For example, the relative positions of the plurality of resonators 29 on the orthogonal coordinate system D1-D2-D3 and the shape and length of the wiring connecting the resonators 29 may be different between the transmission filters 13A and 13B. good.

In this way, the first filter and the second filter (here, the transmission filters 13A and 13B) may be located on the same piezoelectric body 31b.

In this case, for example, the effect of reducing the nonlinear distortion described above is improved. Specifically, it is as follows. In an embodiment in which the transmission filters 13A and 13B are provided on different piezoelectric bodies 31b (this embodiment is also included in the technology according to the present disclosure), even if the transmission filters 13A and 13B have the same configuration in terms of design, The characteristics may differ from each other due to patterning of the electrodes and manufacturing errors of the piezoelectric body 31b and the like. As a result, the nonlinear distortion generated in the transmission filter 13A and the nonlinear distortion generated in the transmission filter 13B are different in intensity and/or phase. As a result, the effect of canceling both out each other may be reduced. However, by providing the transmission filters 13A and 13B on the same piezoelectric body 31b, the probability of such a problem occurring can be reduced.

Note that here, the transmission filters 13A and 13B (such as the first embodiment) are taken as an example as the first filter and the second filter located on the same piezoelectric body 31b. However, the first filter and the second filter located on the same piezoelectric body 31b may be the receiving filters 15A and 15B (such as in the second embodiment).

(Example of terminating resistor)
The terminating resistor 23 may be a conductive pattern formed on a circuit board, as described above. FIG. 8 also serves as a diagram showing an example thereof. In this example, the terminating resistor 23 is constituted by a conductor pattern formed on the upper surface 31a of the substrate 31. However, illustration of the specific shape of the conductor pattern is omitted here, and an example of the arrangement area of the conductor pattern is schematically expressed as a rectangle. The conductor pattern may have an appropriate shape, such as extending in a meandering shape, for example. The terminating resistor 23 is connected to a terminal 53E and a terminal 53G to which a reference potential is applied. Terminal 53E is connected to port 17a of 90° hybrid 17.

In this way, the terminating resistor 23 is made of a piezoelectric material on which at least one of the first filter, the second filter, and the third filter (in the illustrated example, the transmission filters 13A and 13B as the first and second filters) is located. 31b.

In this case, for example, the termination resistor 23 can be formed at the same time as the electrode portion of the filter is formed, so cost reduction is expected. Furthermore, since the electrode portion is formed using photolithography technology, the precision in forming the electrode portion can be increased, and the filter characteristics can be improved.

In FIG. 8, a mode is illustrated in which the piezoelectric body 31b provided with the terminating resistor 23 is provided with transmission filters 13A and 13B. However, as can be understood from the above description, the piezoelectric body 31b on which the terminating resistor 23 is provided is, for example, the piezoelectric body 31b on which the reception filter 15 is located, in addition to or instead of the transmission filters 13A and 13B. It may be the piezoelectric body 31b where only one of the transmission filters 13A and 13B is located, or the piezoelectric body 31b where only one transmission filter 13 of the second embodiment is located. In place of or in addition to the one transmission filter 13, one or both of the two reception filters 15A and 15B of the second embodiment may be located on the piezoelectric body 31b.

(180° hybrid configuration example)
As mentioned above, the 180° hybrids (21, 22 and 24) may be configured in various ways. Two examples are shown below. In the following description, for convenience, the reference numeral 180° hybrid 21 may be used to represent various 180° hybrids.

(1st example of 180° hybrid)
FIG. 9A is a circuit diagram showing a 180° hybrid 21A, which is an example of the 180° hybrid 21. FIG.

In the 180° hybrid 21A, one inductor 55 and three capacitors 57 are connected in a ring. Port 21c and port 21d, whose signals are shifted in phase by 180°, are connected to a node between inductor 55 and capacitor 57. The other ports 21a and 21b are connected to a node between the capacitors 57.

(Second example of 180° hybrid)
FIG. 9(b) is a circuit diagram showing a 180° hybrid 21B, which is an example of the 180° hybrid 21.

The 180° hybrid 21B has four MM filters 59 (59A to 59D). Each MM filter 59 has the same configuration as the MM filter 49 shown in FIG. For example, the MM filter 59 includes a plurality of (two in the illustrated example) excitation electrodes 33 arranged in the propagation direction of elastic waves, and reflectors 35 (not shown in FIG. 9B) located on both sides of the excitation electrodes 33. (omitted). Note that in FIG. 9(b), the excitation electrode 33 is schematically expressed in a lattice shape, unlike its actual configuration. Each MM filter 59 may have three or more excitation electrodes 33.

The MM filter 59 as described above may have a function of outputting the input signal while maintaining its phase, or outputting the input signal with the phase shifted by 180 degrees. For example, referring to the MM filter 49 shown in FIG. 7, a comb-teeth electrode 37 to which a signal is input from the antenna terminal 5 of the excitation electrode 33 at the center of the page, and a receiving electrode of the excitation electrode 33 at the top of the page. The comb-teeth electrode 37 that outputs a signal to the terminal 9 is adjacent to the comb-teeth electrode 37 at an interval of λ/2. Therefore, the phase of the signal output from the excitation electrode 33 at the top of the page is shifted by 180° with respect to the phase of the signal input to the excitation electrode 33 at the center of the page. On the other hand, the comb-teeth electrode 37 to which a signal is input from the antenna terminal 5 of the excitation electrodes 33 in the center of the paper, and the comb-teeth electrode 37 that outputs a signal to the receiving terminal 9 of the excitation electrodes 33 in the lower part of the paper are as follows. Adjacent at an interval of λ. Therefore, the phase of the signal output from the excitation electrode 33 at the top of the page is the same as the phase of the signal input to the excitation electrode 33 at the center of the page.

Therefore, an MM filter 59D is provided between the port 21c and the port 21d so that the input signal and the output signal are out of phase by 180 degrees. Furthermore, between other ports (between port 21d and port 21a, between port 21a and port 21b, and between port 21b and port 21c), the input signal and output signal have the same phase. MM filters 59A, 59B, and 59C configured as follows are provided. This makes it possible to realize a 180° hybrid phase conversion function. In addition, by making the configurations of the four MM filters 59A substantially the same except for the phase conversion function described above, the signal input to one port is distributed at a distribution ratio of 1:1, and the signal input to the other port is distributed at a distribution ratio of 1:1. It can output to two ports.

As described above, the 180° hybrid 21B may include the first to fourth multimode filters (MM filters 59A to 59D). The MM filter 59B connects the first port (port 21b) and the second port (port 21a), and outputs a signal that is in phase with the input signal. The MM filter 59C connects the port 21b and the third port (port 21c), and outputs a signal that is in phase with the input signal. The MM filter 59A connects the port 21a and the fourth port (port 21d), and outputs a signal that is in phase with the input signal. The MM filter 59D connects the port 21c and the port 21d, and outputs a signal having a phase opposite to the input signal.

In this case, for example, the 180° hybrid 21B not only functions as a 180° hybrid (distribution, synthesis, and phase conversion) but also functions as a filter. Therefore, for example, by using the MM filter 59 having a pass band including the pass bands of both the transmit filter 13 and the receive filter 15, it is possible to use the MM filter 59 which has a pass band including the pass bands of both the transmit filter 13 and the receive filter 15. can attenuate signals outside the opposite band. That is, the filter characteristics of the duplexer 1 can be improved. Furthermore, if the MM filter 59 is provided on the piezoelectric body 31b where at least one of the first to third filters (transmission filter 13 and reception filter 15) is provided, the 180° hybrid 21B can be fabricated simultaneously with the production of the first to third filters. It can be made.

Note that in the above 180° hybrid 21B, the MM filter 59B is an example of a first multimode filter. The MM filter 59C is an example of a second multi-mode filter. The MM filter 59A is an example of a third multi-mode filter. The MM filter 59D is an example of a fourth multimode filter.

(3rd example of 180° hybrid)
FIG. 14 is a circuit diagram showing a 180° hybrid 21C, which is an example of the 180° hybrid 21. In FIG. 14, the excitation electrode 33 is schematically represented by a lattice, unlike the actual configuration, as in FIG. 9(b).

The 180° hybrid 21C is configured by an MM filter 59, similar to the 180° hybrid 21B in FIG. 9(b). In the 180° hybrid 21B, one MM filter 59 was used to connect two ports, and a total of four MM filters 59 were used to connect four ports. On the other hand, in the 180° hybrid 21C, one MM filter 59 is used to connect two ports and the other two ports, and a total of two MM filters are used to connect four ports. 59 is used. Specifically, for example, it is as follows.

MM filters 59E and 59F each have three excitation electrodes 33. The ports 21a, 21b, and 21c are connected to different excitation electrodes 33 of the MM filter 59E. These three ports are connected to comb-teeth electrodes 37 (FIG. 6) that are in phase with each other. On the other hand, the ports 21a, 21d, and 21c are connected to different excitation electrodes 33 of the MM filter 59F. The ports 21a and 21c are connected to comb-teeth electrodes 37 that are in phase with each other. The ports 21c and 21d are connected to comb-teeth electrodes 37 having opposite phases. With such a configuration, a 180° hybrid phase conversion function can be realized.

The configurations of the MM filters 59E and 59F are, for example, substantially the same configuration (including a line-symmetric configuration). In the MM filter 59E, the two excitation electrodes 33 to which the port 21a and the port 21c are connected are arranged symmetrically with respect to the excitation electrode 33 to which the port 21b is connected, for example, and have substantially the same configuration. In the MM filter 59F, the two excitation electrodes 33 to which the port 21a and the port 21c are connected are arranged symmetrically with respect to the excitation electrode 33 to which the port 21d is connected, for example, and have substantially the same configuration. Such a configuration realizes a function of distributing signals at a 1:1 distribution ratio of 180° hybrid.

Note that the number of excitation electrodes 33 included in each MM filter 59 may be an odd number greater than three. Further, by appropriately adjusting the configuration of each excitation electrode 33 so that the distribution ratio is 1:1, it is possible to make the number of excitation electrodes 33 included in each MM filter 59 an even number.

(Example of sharing a board by hybrid)
As already mentioned, the filters (13 and/or 15) may be constituted by elastic wave filters. The terminating resistor 23 may be provided on the piezoelectric body. The 180° hybrid (21, 22, and 24) may be configured by an elastic wave filter. These elements may be provided on separate piezoelectric bodies, or two or more of them may be provided on the same piezoelectric body. Below, an example will be shown in which all of these are provided on the same piezoelectric body (from another point of view, the same substrate).

FIG. 15 is a circuit diagram showing an example of a duplexer in which a plurality of elements are provided on the same piezoelectric body. Here, the configuration of a duplexer 401 according to the fourth embodiment is taken as an example.

In this example, all the elements except the phase shifters 19 and 27 are provided on the upper surface of the same piezoelectric body 31b (substrate 31). That is, the 180° hybrids 21 and 22, the transmission filters 13A and 13B, the reception filter 15, and the terminating resistor 23 are provided on the upper surface of the piezoelectric body 31b. Furthermore, the piezoelectric body 31b may be provided with an antenna terminal 5, a transmission terminal 7, and a reception terminal 9. The phase shifters 19 and 27 are connected via terminals provided on the substrate 31, for example. The phase shifter 19 may be realized by a delay line or may be connected by a lumped constant circuit.

(Example of structure of duplexer)
The structure of the duplexer may be any suitable structure. Three examples are shown below. Here, for convenience, the reference numeral of the duplexer 201 according to the second embodiment is given. However, the structural examples illustrated below may be applied to other embodiments.

FIG. 10A is a plan view showing an example of the structure of the duplexer 201.

In this example, each element (13, 15A, 15B, 17, 19 (not shown), 21, and 23) constituting the duplexer 201 is a packaged electronic component. These electronic components are mounted on a circuit board 61 and connected to each other by wiring 63 on the circuit board 61. The phase shifter 19 is realized, for example, by a delay line in the wiring 63 of the circuit board 61. Although not particularly illustrated, other electronic components connected to the duplexer 201 and/or electronic components not connected to the duplexer 201 may be mounted on the circuit board 61. In other words, the duplexer 201 may be a part of a printed circuit board (a printed wiring board and electronic components mounted on the printed wiring board). In this way, in the duplexer 201, the elements other than the duplexer main body 3 may not be packaged together with the duplexer main body 3, but may be made external electronic components to the duplexer main body 3.

FIG. 10(b) is a plan view showing another example of the structure of the duplexer 201.

In this example, the elements (13, 15A, 15B, 17, 19 (not shown), 21, and 23) constituting the duplexer 201 are packaged together to form one electronic component. For example, the duplexer 201 has a circuit board 65 on which each element is mounted. The transmission filter 13 and the reception filters 15A and 15B may be in the form of bare chips or wafer level packages, for example. The other elements may be in a packaged state or may be in an unpackaged state. A plurality of elements constituting the duplexer 201 are sealed together with a resin or the like (not shown) that covers the upper surface of the circuit board 65. The circuit board 65 is provided with an antenna terminal 5, a transmission terminal 7, and a reception terminal 9 at appropriate positions.

FIG. 10(c) is a plan view showing still another example of the structure of the duplexer 201.

In this example, similarly to the example of FIG. 10(b), the elements (13, 15A, 15B, 17, 19 (not shown), 21 and 23) constituting the duplexer 201 are packaged together. It is considered as one electronic component. For example, the duplexer 201 has a circuit board 67 on which each element is mounted. However, some of the elements (in the illustrated example, all the elements other than the duplexer main body 3) are built into the circuit board 67. That is, each element is configured by providing a conductor inside or on the surface of the circuit board 67.

The circuit boards 61, 65, and 67 may take various known forms. For example, these substrates may be LTCC (Low Temperature Co-fired Ceramics) substrates, HTCC (High Temperature Co-Fired Ceramic) substrates, or organic substrates.

The structural examples of FIGS. 10(a) to 10(c) may be combined. For example, some of the elements (17, 19, 21, and 23) other than the duplexer body 3 may be packaged together with the duplexer body 3, and other elements may be attached externally. good. Furthermore, for example, in a case where all or some of the multiple elements other than the duplexer body 3 are packaged together with the duplexer body 3, some of the multiple elements to be packaged may be mounted on the circuit board. and the rest may be built into the circuit board. Further, for example, some elements may be built into the circuit board 61 on which external elements are mounted. Furthermore, the configurations shown in FIGS. 10(a) to 10(c) and the configuration shown in FIG. 15 may be combined. That is, in FIGS. 10(a) to 10(c) or a combination thereof, some of the elements may be provided on the same piezoelectric body 31b.

(Communication device)
FIG. 11 is a block diagram showing the main parts of a communication device 151 as an example of how the duplexer 1 is used. The communication device 151 performs wireless communication using radio waves, and includes a duplexer 1, for example. Here, only the transmission filter 13 and reception filter 15 of the duplexer 1 are shown. Further, the two transmission filters 13A and 13B are expressed as one transmission filter 13.

In the communication device 151, a transmission information signal TIS containing information to be transmitted is modulated and frequency raised (converted to a high frequency signal having a carrier frequency) by an RF-IC (Radio Frequency Integrated Circuit) 153 to become a transmission signal TS. It is said that The transmission signal TS has unnecessary components outside the transmission passband removed by a bandpass filter 155, is amplified by an amplifier 157, and is input to the duplexer 1 (transmission terminal 7). Then, the duplexer 1 (transmission filter 13) removes unnecessary components other than the transmission passband from the input transmission signal TS, and outputs the removed transmission signal TS from the antenna terminal 5 to the antenna 159. . The antenna 159 converts the input electric signal (transmission signal TS) into a wireless signal (radio wave) and transmits the signal.

Furthermore, in the communication device 151, a radio signal (radio wave) received by the antenna 159 is converted into an electric signal (received signal RS) by the antenna 159, and is input to the duplexer 1 (antenna terminal 5). The duplexer 1 (reception filter 15) removes unnecessary components outside the reception passband from the input reception signal RS, and outputs the signal from the reception terminal 9 to the amplifier 161. The output reception signal RS is amplified by an amplifier 161, and a bandpass filter 163 removes unnecessary components outside the reception passband. Then, the received signal RS is frequency lowered and demodulated by the RF-IC 153 to become a received information signal RIS.

Note that the transmission information signal TIS and the reception information signal RIS may be low frequency signals (baseband signals) containing appropriate information, such as analog audio signals or digitized signals. The passband of the wireless signal may be set as appropriate, and may be a relatively high frequency passband (for example, 5 GHz or higher). The modulation method may be phase modulation, amplitude modulation, frequency modulation, or a combination of two or more of these. As for the circuit system, although a direct conversion system is illustrated in FIG. 11, any other suitable circuit system may be used, for example, a double superheterodyne system may be used. Further, FIG. 11 schematically shows only the main parts, and a low-pass filter, an isolator, etc. may be added at an appropriate position, or the position of an amplifier, etc. may be changed.

The technology according to the present disclosure is not limited to the above embodiments, and may be implemented in various ways.

Composite filters are not limited to duplexers. For example, the composite filter may include two transmission filter systems with different passbands as the first and second filter systems. Further, the composite filter may include two receiving filter systems having different passbands as the first and second filter systems. Furthermore, the composite filter may include a filter system in addition to the first and second filter systems. For example, the composite filter may be a triplexer with three filter systems or a quadplexer with four filter systems.

1... Duplexer (composite filter), 2T... Transmission filter system (first filter system), 2R... Reception filter system (second filter system), 5... Antenna terminal (common terminal), 7... Transmission terminal (first terminal or second terminal), 9... Reception terminal (second terminal or first terminal), 13... Transmission filter (first filter, second filter, or third filter), 13A... Transmission filter (first filter), 13B ...Transmission filter (second filter), 15...Reception filter (first filter, second filter, or third filter), 15A...Reception filter (first filter), 15B...Reception filter (second filter), 17...90 °Hybrid (auxiliary circuit), 17a...port (5th port), 17b...port (6th port), 17c...port (7th port), 17d...port (8th port), 19...90° phase shifter, 21...180° hybrid, 21a...port (second port), 21b...port (first port), 21c...port (third port), 21d...port (fourth port).

Claims (12)

common terminal and
a first terminal;
a second terminal;
a first filter system connecting the common terminal and the first terminal;
a second filter system connecting the common terminal and the second terminal;
It has
The first filter system and the second filter system share a 180° hybrid connected to the common terminal,
The 180° hybrid has a first port, a second port and a third port that are electrically connected to the first port, and a fourth port that is electrically connected to the second port and the third port. The second port and the third port are ports to which signals of the same phase are distributed from the first port, and the fourth port is a port to which signals of the same phase are distributed from the third port to the first port. a port to which a signal having a phase shifted by 180° with respect to a phase of a signal to be distributed is distributed from the third port, and the first port is connected to the common terminal,
The first filter system is
a first filter connected to the second port and corresponding to a first passband;
a 90° phase shifter connected to the third port;
a second filter connected to the third port via the 90° phase shifter and corresponding to the first passband;
The first filter and the second filter are connected to the first terminal, and the phase of the signal flowing between the first terminal and the first filter is adjusted between the first terminal and the second filter. It has an auxiliary circuit that shifts the signal by 90 degrees with respect to the signal flowing through the
The second filter system is
A composite filter including a third filter that corresponds to a second passband different from the first passband and connects the fourth port and the second terminal. The composite filter according to claim 1, wherein each of the first filter, the second filter, and the third filter is a piezoelectric filter. The composite filter according to claim 2, wherein the first filter and the second filter are located on the same piezoelectric body. The auxiliary circuit is a 90° hybrid, and has a fifth port and a sixth port, a seventh port that is electrically connected to the fifth port and the sixth port, and a seventh port that is electrically electrically connected to the fifth port and the sixth port. and an eighth port, and the seventh port receives a signal having a phase shifted by 90 degrees from the phase of the signal distributed from the sixth port to the eighth port. It is a port distributed from
the sixth port is connected to the first terminal,
the seventh port is connected to the first filter,
The composite filter according to any one of claims 1 to 3, wherein the eighth port is connected to the second filter. the auxiliary circuit has a second 180° hybrid and a second 90° phase shifter;
The second 180° hybrid has a fifth port, a sixth port and a seventh port that are in communication with the fifth port, and an eighth port that is in communication with the sixth port and the seventh port. , the sixth port and the seventh port are ports to which signals of the same phase are distributed from the fifth port, and the eighth port is a port to which signals of the same phase are distributed from the seventh port to the fifth port. A port to which a signal having a phase shifted by 180° from the phase of a signal distributed to the port is distributed from the seventh port,
the fifth port is connected to the first terminal,
the sixth port is connected to the first filter via the second 90° phase shifter;
The composite filter according to any one of claims 1 to 3, wherein the seventh port is connected to the second filter. the auxiliary circuit has a second 180° hybrid and a second 90° phase shifter;
The second 180° hybrid has a fifth port, a sixth port and a seventh port that are in communication with the fifth port, and an eighth port that is in communication with the sixth port and the seventh port. , wherein the sixth port is a port to which a signal having a phase shifted by 180° from the phase of the signal distributed from the fifth port to the seventh port is distributed from the fifth port. The fifth port and the eighth port are ports to which signals of the same phase are distributed from the seventh port,
the fifth port is connected to the first terminal,
the sixth port is connected to the first filter,
The composite filter according to any one of claims 1 to 3, wherein the seventh port is connected to the second filter via the second 90° phase shifter. The composite filter according to claim 5 or 6, wherein the second 180° hybrid is constituted by a multimode filter. The composite filter according to claim 4, further comprising a terminating resistor connected to the fifth port. The composite filter according to claim 8, wherein the terminating resistor is located in a piezoelectric body on which at least one of the first filter, the second filter, and the third filter is located. The 180° hybrid is
a first multimode filter that connects the first port and the second port and outputs a signal that is in phase with the input signal;
a second multimode filter that connects the first port and the third port and outputs a signal that is in phase with the input signal;
a third multi-mode filter that connects the second port and the fourth port and outputs a signal that is in phase with the input signal;
A fourth multi-mode filter that connects the third port and the fourth port and outputs a signal having a phase opposite to the input signal. 9. The composite filter according to any one of 9. The 180° hybrid is
The first port, the second port, and the third port are connected,
a first multimode filter that outputs a signal that is in phase with a signal input between the first port and the second port and between the first port and the third port;
connected to the second port, the third port, and the fourth port,
outputting a signal that is in phase with the signal input between the fourth port and the second port;
a second multimode filter that outputs a signal that is in opposite phase to the signal input between the fourth port and the third port;
The composite filter according to any one of claims 1 to 9, comprising: A composite filter according to any one of claims 1 to 10,
an antenna connected to the common terminal;
an integrated circuit element connected to the first terminal and the second terminal;
A communication device that has

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