KR20170138953A - Multiplexer and radio-frequency (rf) front-end module - Google Patents

Abstract

The present invention relates to a multiplexer and a high-frequency front-end module. When an elastic wave filter is used in the multiplexer, the multiplexer can suppress degradation of passing properties of other filters configuring the same multiplexer. The multiplexer comprises: a first filter (11) arranged between a common terminal (15) and a first terminal (16); and a second filter (12) which is arranged between the common terminal (15) and a second terminal (17) while having a higher pass-band frequency than the first filter (11). The second filter (12) has multiple inter-digital transducers (IDTs, 211 to 215) arranged to be coupled in a vertical manner. IDT electrodes (212b, 214b) on one side among multiple IDT electrodes configuring the IDTs (211 to 215) are connected to the common terminal (15). IDT electrodes (212b, 214b) on the other side are connected to the second terminal (17). The IDT electrodes on both sides have different main pitch (m) values regarding multiple electrode fingers. One or more among the IDT electrodes on the other side have the maximum main pitch (m) value regarding the electrode fingers.

Description

MULTIPLEXER AND RADIO-FREQUENCY (RF) FRONT-END MODULE}

The present invention relates to a multiplexer having a plurality of filters and a high-frequency front end module including the multiplexer.

BACKGROUND ART [0002] In recent mobile phones, a single terminal is required to support a plurality of frequency bands and a plurality of radio systems, so-called multi-band and multi-mode. In order to cope with this, a multiplexer for demultiplexing a high-frequency signal having a plurality of radio carrier frequencies is disposed immediately below one antenna. As the plurality of bandpass filters constituting the multiplexer, an acoustic wave filter or the like is used which is characterized by low loss within the pass band and the steepness of the pass characteristic around the pass band.

As an example of this acoustic wave filter, Patent Document 1 discloses a longitudinally coupled acoustic wave filter having five IDT (Inter Digital Transducer) portions. In this elastic wave filter, five IDT portions are arranged on the piezoelectric substrate along the propagation direction of the acoustic wave.

International Publication No. 2013/069225

In the elastic wave filter disclosed in Patent Document 1, the first IDT electrode, the third IDT electrode, and the fifth IDT electrode among the five IDT portions are commonly connected to one input side terminal (unbalanced terminal), and the second IDT electrode and the fourth IDT electrodes are connected to the terminals (balanced terminals) on the other output side which are different from each other. In the description of paragraph [0025] of Patent Document 1, the pitch of the electrode fingers of the first and fifth IDT electrodes is 1.0582 μm, the pitch of the electrode fingers of the second and fourth IDT electrodes is 1.0569 μm, The pitch of the electrode fingers of the electrode is 1.0612 mu m. That is, the IDT electrode having the largest electrode finger pitch (in the case of Patent Document 1, the third IDT electrode) is connected to the input side terminal.

In order to cope with the above-described multi-banding and the like, a multiplexer having a plurality of filters is used. In this regard, the inventors have found that when the elastic wave filter having the pitch of the electrode fingers as described above is used as the filter of the multiplexer, the passing characteristics of other filters constituting the same multiplexer may be lowered.

Therefore, it is an object of the present invention to suppress degradation of the passing characteristics of other filters constituting the same multiplexer when an acoustic wave filter is used in a multiplexer.

According to one aspect of the present invention, there is provided a multiplexer comprising: a common terminal; a first terminal; a second terminal; a first filter disposed on a path connecting the common terminal and the first terminal; And a second filter disposed on a path connecting the common terminal and the second terminal and having a higher passband frequency than the first filter, wherein the second filter is an elastic wave filter, and the propagation direction of the elastic wave is Wherein each of the plurality of IDT portions is constituted by a set of IDT electrodes opposed to each other, and of the plurality of IDT electrodes constituting the plurality of IDT portions, one of the plurality of IDT portions is common to the common Terminal and the second terminal, and the other IDT electrode is connected to the second terminal side of the common terminal and the second terminal, and the other IDT electrode and the other IDT electrode are connected to the second terminal side,Each of the electrodes has a plurality of electrode fingers formed on the surface of the piezoelectric substrate and arranged in the propagation direction of the acoustic wave, and the main pitches of the electrode fingers of the one IDT electrode and the other IDT electrode are different , And at least one of the other IDT electrodes has a main pitch of the electrode fingers of the plurality of IDT electrodes.

Thus, by setting the main pitch of the electrode finger to at least one of the other IDT electrodes to be the maximum, the position of the unwanted wave whose return loss of the second filter generated in the frequency passband of the first filter becomes large is set to the first It is possible to move it out of the pass band of the filter. Thereby, when the acoustic wave filter is used in the multiplexer, it is possible to suppress the degradation of the passing characteristics of other filters constituting the same multiplexer.

At least one of the IDT electrodes may have a minimum pitch between the electrode fingers of the plurality of IDT electrodes.

In this manner, by setting the main pitch of the electrode finger to at least one of the IDT electrodes on one side, the position of the unwanted wave whose return loss of the second filter generated in the pass band of the first filter becomes large, Frequency band side of the second filter and can be moved to the band of the low-frequency side stop band of the second filter. Thereby, when the acoustic wave filter is used in the multiplexer, it is possible to suppress the degradation of the passing characteristics of other filters constituting the same multiplexer.

According to another aspect of the present invention, there is provided a multiplexer comprising: a common terminal; a first terminal; a second terminal; a first filter disposed on a path connecting the common terminal and the first terminal; And a second filter disposed on a path connecting the second terminal and having a higher passband frequency than the first filter, wherein the second filter is an elastic wave filter, and the plurality of IDT portions of the plurality of IDT portions, each of the plurality of IDT portions is constituted by a set of IDT electrodes opposed to each other, and of the plurality of IDT electrodes constituting the plurality of IDT portions, one of the IDT electrodes is connected to the common terminal and the And the other IDT electrode is connected to the second terminal side of the common terminal and the second terminal, and each of the one IDT electrode and the other IDT electrode is connected to the common terminal side of the two IDT electrodes, Piezoelectric And a plurality of electrode fingers formed on the surface of the substrate and arranged in the propagation direction of the elastic wave, wherein the electrode fingers of the one IDT electrode and the other IDT electrode have different main pitches, The total average of the pitches of the electrode fingers of the electrode is smaller than the total average of the pitches of the electrode fingers of the other IDT electrode.

By making the total average of the pitches of the electrode fingers of one IDT electrode smaller than the total average of the pitches of the electrode fingers of the other IDT electrode as described above, It becomes possible to move the position of the unwanted wave whose return loss becomes large out of the pass band of the first filter. Thereby, when the acoustic wave filter is used in the multiplexer, it is possible to suppress the degradation of the passing characteristics of other filters constituting the same multiplexer.

According to another aspect of the present invention, there is provided a multiplexer comprising: a common terminal; a first terminal; a second terminal; a first filter disposed on a path connecting the common terminal and the first terminal; And a second filter disposed on a path connecting the second terminal and having a higher passband frequency than the first filter, wherein the second filter is an elastic wave filter, and the plurality of IDT portions of the plurality of IDT portions, each of the plurality of IDT portions is constituted by a set of IDT electrodes opposed to each other, and of the plurality of IDT electrodes constituting the plurality of IDT portions, one of the IDT electrodes is connected to the common terminal and the And the other IDT electrode is connected to the second terminal side of the common terminal and the second terminal, and each of the one IDT electrode and the other IDT electrode is connected to the common terminal side of the two IDT electrodes, Piezoelectric And a plurality of electrode fingers formed on the surface of the substrate and arranged in the propagation direction of the elastic wave, wherein the electrode fingers of the one IDT electrode and the other IDT electrode have different main pitches, When the average value of the pitches of the electrode fingers is obtained in the electrode, the IDT electrode having the maximum average value exists in the other IDT electrode.

In this way, when the average value of the pitches of the electrode fingers is obtained for each of the IDT electrodes, the IDT electrode having the maximum average value exists in the other IDT electrode, It is possible to move the position of the unwanted wave whose return loss becomes large, out of the pass band of the first filter. Thereby, when the acoustic wave filter is used in the multiplexer, it is possible to suppress the degradation of the passing characteristics of other filters constituting the same multiplexer.

Further, in the case where the average value of the pitch of the electrode fingers is obtained in each of the IDT electrodes, the IDT electrode having the smallest average value may be present in the one IDT electrode.

As described above, since the IDT electrode having the smallest average value is present in one IDT electrode, the position of the unwanted wave whose return loss of the second filter generated in the pass band of the first filter becomes larger than the pass band of the first filter Side band of the second filter, and can be moved into the band of the low-frequency-side stop band of the second filter. Thereby, when the acoustic wave filter is used in the multiplexer, it is possible to suppress the degradation of the passing characteristics of other filters constituting the same multiplexer.

Further, a circuit element different from the second filter may be connected between the one IDT electrode and the common terminal.

Thus, even when a circuit element different from the second filter is connected between one of the IDT electrodes and the common terminal, the position of the unwanted wave whose return loss of the second filter generated in the frequency passband of the first filter becomes large It is possible to move out of the pass band of the first filter. This makes it possible to suppress the degradation of the passing characteristics of other filters constituting the same multiplexer.

Further, the second filter has odd number of IDT portions of 3 or more, and the number of the IDT electrodes is smaller than the number of the other IDT electrodes.

This makes it possible to easily move the position of the unwanted wave whose return loss of the second filter increases in the pass band of the first filter to the high frequency side easily. In the case where the acoustic wave filter is used in the multiplexer, the same multiplexer It is possible to suppress deterioration of the passing characteristics of the other filters.

The second filter may have five or more IDT portions.

According to this, the frequency pass band of each of the first filter and the second filter can be extended.

The first filter and the second filter may be reception filters.

According to this, it is possible to provide a multiplexer including a plurality of receiving filters, which can suppress the degradation of the passing characteristics of other filters constituting the same multiplexer when the acoustic wave filter is used.

Further, when the first filter is connected to the common terminal, the second filter may be connected to the common terminal.

This makes it possible to move the spurious wave out of the pass band of the first filter, even when a spurious wave whose return loss of the second filter becomes large in the pass band of the first filter is generated. Thereby, when the acoustic wave filter is used in the multiplexer, it is possible to suppress the degradation of the passing characteristics of other filters constituting the same multiplexer.

Further, a high-frequency front end module according to another aspect of the present invention includes the multiplexer.

As described above, in the multiplexer of the high-frequency front-end module, at least one of the other IDT electrodes has the main pitch of the electrode finger at the maximum, so that the return loss of the second filter generated in the frequency passband of the first filter is It becomes possible to move the position of the unwanted unwanted wave out of the pass band of the first filter. Thereby, when the acoustic wave filter is used in the high-frequency front end module, it is possible to suppress the degradation of the passing characteristics of other filters constituting the same multiplexer.

The present invention can suppress the degradation of the passing characteristics of other filters constituting the same multiplexer or high-frequency front end module when an acoustic wave filter is used in a multiplexer or a high-frequency front end module.

1A is a circuit configuration diagram of a communication apparatus including a multiplexer according to the embodiment.
1B is a schematic diagram showing insertion loss (passing characteristic) of a multiplexer according to the embodiment.
2 is a circuit diagram showing a multiplexer having a first filter and a second filter, which is a multiplexer according to the embodiment;
3 is a schematic plan view showing a second filter of the multiplexer shown in Fig.
Fig. 4 is a diagram schematically showing the IDT portion of the second filter shown in Fig. 2. Fig. 4 (a) is a plan view and Fig. 4 (b) is a sectional view.
5 is a schematic plan view showing a second filter of a multiplexer according to a comparative example.
6 is a diagram showing the insertion loss in the frequency passband of the first filter.
7 is a diagram showing the return loss of the second filter in the frequency passband of the first filter.
8 is a circuit configuration diagram of a high-frequency front end module including a multiplexer according to the embodiment.
Fig. 9 is a schematic plan view showing the configuration of the second filter side of the multiplexer according to another embodiment. Fig.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the embodiments and drawings. Further, the embodiments described below are all inclusive or specific examples. The numerical values, shapes, materials, constituent elements, arrangements and connection forms of the constituent elements and the like appearing in the following embodiments are merely examples, and are not intended to limit the present invention. Among the constituent elements in the following embodiments, constituent elements not described in the independent claims are described as arbitrary constituent elements. Also, the ratio of the size or size of the constituent elements shown in the drawings is not necessarily strict.

(Embodiments)

[One. Overall Configuration of Multiplexer]

1A is a circuit configuration diagram of a communication device 9 including a multiplexer 1 according to the embodiment. Fig. 1B is a schematic diagram showing the insertion loss (passing characteristic) of the multiplexer 1 according to the embodiment. Fig.

The communication apparatus 9 includes a multiplexer 1 and a radio frequency integrated circuit (RFIC) 4 as a high-frequency signal processing circuit, as shown in Fig. 1A. The multiplexer 1 is connected to the antenna element 2 via the common terminal 15. [

1A shows an example of the multiplexer 1, and Band 25 (transmission band: 1850-1915 MHz, reception band-pass band: 1930-1995 MHz) and Band-66 (transmission band: 1710- 1780 MHz, and the reception pass band: 2110-2200 MHz).

The multiplexer 1 includes transmission filters 101 and 103, reception filters 102 and 104, a common terminal 15, transmission input terminals 106 and 108, reception output terminals 107 and 109 . Each of the transmission filters 101 and 103 and the reception filters 102 and 104 is connected to the common terminal 15 by bundling the respective outgoing lines.

Each of the transmission filters 101 and 103 receives a transmission wave generated in the RFIC 4 via each of the transmission input terminals 106 and 108 and filters the transmission wave in each transmission band, Which is a band-pass filter.

Each of the receiving filters 102 and 104 is a band-pass filter that receives a receiving wave input from the common terminal 15, filters the signals in the respective receiving bands, and outputs them to the respective receiving output terminals 107 and 109.

Here, in order to understand the essence of the multiplexer 1 of the present embodiment, attention should be paid to any two filters included in the multiplexer 1 of Fig. 1A. Each of the two noted filters is referred to as a first filter 11 and a second filter 12.

Fig. 2 is a circuit diagram showing a multiplexer 1A including a first filter 11 and a second filter 12. Fig.

As shown in FIG. 2, the first filter 11 is disposed on a path connecting the common terminal 15 and the first terminal 16. The second filter 12 is disposed on a path connecting the common terminal 15 and the second terminal 17. [ The second filter 12 is connected to the common terminal 15 at least when the first filter 11 is connected to the common terminal 15 and filtering is performed.

The frequency of the pass band of the second filter (12) is higher than that of the first filter (11). In the present embodiment, as an example, the first filter 11 is assumed to be a band-pass band (band 25 Rx) filter and the second filter 12 is assumed to be a band-pass band (band 66 Rx) filter.

[2. Structure of the IDT portion of the second filter]

3 is a schematic plan view showing the second filter 12 of the multiplexer 1A.

The second filter 12 is a longitudinally coupled acoustic wave filter and has a plurality of IDT portions 211, 212, 213, 214 and 215. The first filter 11 may be a ladder filter having a series resonator and a parallel resonator, or a longitudinally coupled acoustic wave filter.

The structure of the IDT portions 211 to 215 constituting the second filter 12 is described by using the IDT portion 22 common to the IDT portions 211 to 215 Explain.

4 is a diagram schematically showing the IDT portion 22, wherein (a) is a plan view and (b) is a sectional view. The IDT portion 22 is for explaining a typical structure of the acoustic wave filter, and the number and length of the electrode fingers constituting the electrode are not limited to this.

The IDT portion 22 is composed of IDT (Inter Digital Transducer) electrodes 22a and 22b having a comb shape.

As shown in Fig. 4 (a), on the piezoelectric substrate 326, a set of IDT electrodes 22a and 22b facing each other is formed. The IDT electrode 22a is composed of a plurality of electrode fingers 222a parallel to each other and a bus bar electrode 221a connecting a plurality of electrode fingers 222a. The IDT electrode 22b is composed of a plurality of electrode fingers 222b parallel to each other and a bus bar electrode 221b connecting a plurality of electrode fingers 222b. The plurality of electrode fingers 222a and 222b are formed along a direction orthogonal to the propagation direction of the acoustic wave. That is, the electrode fingers 222a and 222b are arranged in the propagation direction of the acoustic wave.

4 (b), the IDT electrodes 22a and 22b composed of the plurality of electrode fingers 222a and 222b and the bus bar electrodes 221a and 221b are formed on the adhesive layer 323, And a main electrode layer 324 are stacked.

The adhesion layer 323 is a layer for improving the adhesion between the piezoelectric substrate 326 and the main electrode layer 324, and for example, Ti is used as the material. The thickness of the adhesion layer 323 is, for example, 12 nm.

As the material of the main electrode layer 324, for example, Al containing 1% of Cu is used. The thickness of the main electrode layer 324 is, for example, 162 nm.

The protective layer 325 is formed so as to cover the IDT electrodes 22a and 22b. The protective layer 325 is intended to protect the main electrode layer 324 from the external environment, to adjust the frequency-temperature characteristics, and to increase the moisture resistance, and is, for example, a film containing silicon dioxide as a main component .

The piezoelectric substrate 326 is made of, for example, LiTaO ₃ piezoelectric single crystal having a predetermined cut angle, LiNbO ₃ piezoelectric single crystal, or piezoelectric ceramics.

Here, the design parameters of the IDT portion 22 will be described. The wavelength of the surface acoustic wave resonator is defined by a repetitive pitch lambda of a plurality of electrode fingers 222a and 222b constituting the IDT 22 shown in Fig. 4B. The intersection width L of the IDT electrode is set such that the electrode finger 222a of the IDT electrode 22a and the electrode finger 222b of the IDT electrode 22b extend in the propagation direction of the acoustic wave Is the overlapping electrode finger length in the case of FIG. The duty ratio D is a line width occupancy rate of a plurality of electrode fingers 222a and 222b and is a ratio of the line width to an added value of a line width and a space width of a plurality of electrode fingers 222a and 222b. More specifically, the duty ratio is set such that the line width of the electrode fingers 222a and 222b constituting the IDT electrodes 22a and 22b is W and the space between the adjacent electrode fingers 222a and 222b When the width is S, it is defined as W / (W + S).

[3. Configuration of Second Filter in Embodiment]

As described above, the second filter 12 is a longitudinally coupled acoustic wave filter, and has a plurality of IDT portions 211 to 215 as shown in Fig. The second filter 12 also has reflectors 220 and 221 and a first port 230 and a second port 240. The first port 230 is provided on the common terminal 15 side of the common terminal 15 and the second terminal 17 as viewed from the plurality of IDT portions 211 to 215. The second port 240 is provided on the second terminal 17 side of the common terminal 15 and the second terminal 17 as viewed from the plurality of IDT portions 211 to 215.

In the second filter 12, for example, when a high frequency signal is inputted from the common terminal 15, a potential difference is generated between the common terminal 15 and the reference terminal (ground) A surface acoustic wave is generated. Here, by making the pitch lambda of each electrode finger of the IDT portions 211 to 215 substantially coincide with the wavelength of the pass band, the second filter 12 is used to obtain a high frequency signal having a frequency component to be passed through Can pass.

The IDT portion 211 of the second filter 12 has a set of IDT electrodes 211a and 211b facing each other. Similarly, each of the IDT portions 212 to 215 has a set of IDT electrodes 212a and 212b, 213a and 213b, 214a and 214b, and 215a and 215b, which are opposed to each other. The IDT portions 211 to 215 are arranged in order along the propagation direction of the acoustic wave so as to be longitudinally coupled. That is, the IDT portions 212 and 214 are arranged so as to sandwich the IDT portion 213 in the propagation direction, and the IDT portions 211 and 215 are arranged to sandwich the IDT portions 212 to 214 in the propagation direction Respectively. The reflectors 220 and 221 are arranged so as to sandwich the IDT portions 211 to 215 in the propagation direction.

The IDT portions 212 and 214 are connected in parallel between the first port 230 and the reference terminal (ground). Specifically, the IDT electrodes 212a and 214a are connected to a reference terminal. The IDT electrodes 212b and 214b are connected to the common terminal 15 side of the common terminal 15 and the second terminal 17 through the first port 230. [

The IDT portions 211, 213, and 215 are connected in parallel between the second port 240 and the reference terminal. More specifically, the IDT electrodes 211a, 213a, and 215a are connected to a reference terminal. The IDT electrodes 211b, 213b and 215b are connected to the second terminal 17 side of the common terminal 15 and the second terminal 17 through the second port 240. [

In this manner, in the second filter 12, one of the IDT electrodes 212b and 214b among the plurality of IDT portions 211 to 215 is connected to the common terminal 15 side, and the other IDT electrode 211b and 213b And 215b are connected to the second terminal 17 side. That is, the connection destination of one of the IDT electrodes 212b and 214b is the common terminal 15 and the connection destination of the other of the IDT electrodes 211b, 213b, and 215b is the second terminal 17.

Table 1 shows the design parameters (main pitch lambda m of the electrode finger, cross width L, number N of IDT pairs, duty ratio D) of the IDT portions 211 to 215.

The electrode finger pitches of the reflectors 220 and 221 are 1.855 占 퐉 and larger than the electrode finger main pitches? 1 to? 5 of the IDT portions 211 to 215, respectively.

The main pitch lambda m of the electrode fingers shown in Table 1 is the pitch of the electrode fingers in the center of each of the IDT electrodes 211b to 215b. The main pitch lambda m is a pitch formed by the electrode fingers occupying 50% or more of all the electrode fingers of the IDT electrode 211b, taking the IDT electrode 211b as an example. In the longitudinally coupled acoustic wave filter, the pitch of the electrode fingers at both ends of the IDT electrode 211b may be made smaller than the center portion in order to adjust the degree of coupling with the adjacent IDT electrode 212b. Therefore, the pitch lambda of the electrode finger becomes a different value at the central portion of the IDT electrode 211b in the propagation direction of the acoustic wave and at both ends when viewed from the entire IDT electrode 211b. Therefore, in the present embodiment, when the pitches lambda of the electrode fingers of the IDT electrodes 211b to 215b are compared, the comparison may be made at the main pitch lambda m.

In this embodiment, as shown in Table 1, the main pitch lambda m of each electrode finger has the following relationship.

(? 2 =? 4) <(? 1 =? 5) <? 3

Namely, the main pitches lambda 2 and lambda 4 of the electrode fingers of one of the IDT electrodes 212b and 214b connected to the common terminal 15 and the other IDT electrodes 211b and 213b connected to the second terminal 17 , 215b are different from each other in the main pitches lambda 1, lambda 3 and lambda 5 of the electrode fingers.

The main pitch lambda 3 of the electrode fingers of the other IDT electrode 213b connected to the second terminal 17 out of the main pitches lambda 1 to lambda 5 of the plurality of IDT electrodes 211b to 215b is the maximum pitch . Of the main pitches lambda 1 to lambda 5, the main pitches lambda 2 and lambda 4 of the IDT electrodes 212b and 214b connected to the common terminal 15 are minimized.

In this embodiment, the total average of the pitch lambda of the plurality of electrode fingers included in one of the IDT electrodes 212b and 214b is the pitch of the plurality of electrode fingers of the other IDT electrodes 211b, 213b, and 215b is smaller than the total average of?. The total average of the pitch lambda of the plurality of electrode fingers is obtained by weighted average of the pitch lambda of the electrode fingers including the center portion and the end portion of the IDT electrode. The total average of the pitches of the electrode fingers of one of the IDT electrodes 212b and 214b is 1.789 占 퐉 and the total average of the pitches of the electrode fingers of the other IDT electrode 211b, 213b, and 215b is 1.819 占 퐉 to be.

In this embodiment, in the case where the average value of the pitch lambda of the plurality of electrode fingers is obtained in each of the IDT electrodes 211b to 215b, the IDT electrode having the maximum average value is arranged on the other IDT electrode 211b, 213b, and 215b. The average value of the pitch lambda of the plurality of electrode fingers is a value obtained by obtaining a weighted average of the pitch lambda of the electrode fingers including the center portion and the end portion of the IDT electrode for each IDT electrode. In the present embodiment, the IDT electrode having the maximum average value is the IDT electrode 213b, and the IDT electrode having the smallest average value is the IDT electrode 212b and 214b.

[4. Configuration of Second Filter in Comparative Example]

5 is a schematic plan view showing a second filter 552 of a multiplexer according to a comparative example.

5, the second filter 552 includes a plurality of IDT portions 511 to 515, reflectors 220 and 221, a first port 230 and a second port 240 .

The IDT portion 511 has a set of IDT electrodes 511a and 511b facing each other. Similarly, each of the IDT portions 512 to 515 has a set of IDT electrodes 512a and 512b, 513a and 513b, 514a and 514b, and 515a and 515b, which are opposed to each other. The IDT portions 511 to 515 are arranged in order along the propagation direction of the acoustic wave so as to be longitudinally coupled.

The IDT portions 511, 513, and 515 are connected in parallel between the first port 230 and the reference terminal (ground). Specifically, the IDT electrodes 511a, 513a, and 515a are connected to a reference terminal. The IDT electrodes 511b, 513b, and 515b are connected to the common terminal 15 through the first port 230. [

IDT portions 512 and 514 are connected in parallel between the second port 240 and the reference terminal. Specifically, the IDT electrodes 512a and 514a are connected to a reference terminal. The IDT electrodes 512b and 514b are connected to the second terminal 17 through the second port 240. [

As described above, in the second filter 552 of the comparative example, the IDT electrodes 511b, 513b, and 515b of the plurality of IDT portions 511 to 515 are connected to the common terminal 15, And the terminals 512b and 514b are connected to the second terminal 17.

Table 2 shows the design parameters of the IDT portions 511 to 515 of the comparative example.

The electrode finger pitch of the reflectors 220 and 221 is 1.861 mu m which is larger than the electrode finger main pitch lambda 1 of the IDT portion 511 and smaller than the electrode finger main pitch lambda 3 of the IDT portion 513. [

In the comparative example, as shown in Table 2, the main pitch lambda m of the electrode finger has the following relationship.

(? 2 =? 4) <(? 1 =? 5) <? 3

The magnitude of the main pitch lambda m of the electrode finger in the comparative example is the same as in the embodiment. Note that in the comparative example, since the IDT electrodes 511b, 513b, and 515b are connected to the common terminal 15 and the IDT electrodes 512b and 514b are connected to the second terminal 17, It is different.

[5. Frequency characteristics of the embodiment and the comparative example]

Hereinafter, the frequency characteristics of the multiplexer in the present embodiment and the comparative example will be described.

Fig. 6 is a diagram showing the insertion loss in the frequency passband of the first filter 11. Fig. As an evaluation circuit corresponding to the embodiment, a circuit in which one of the first filter 11 and the second filter 12 is connected to each other is used as shown in Fig. 6 (a). As the evaluation circuit corresponding to the comparative example, a circuit obtained by replacing the second filter 12 of the embodiment with the second filter 552 of the comparative example was used.

6 (b) is a diagram showing the insertion loss (transmission characteristic) of each of the embodiment and the comparative example at 1850 MHz to 2050 MHz. As shown in Fig. 6B, in the comparative example, the insertion loss is large at around 1975 MHz within the band of Band25Rx. On the other hand, in the embodiment, the insertion loss in the vicinity of 1975 MHz is smaller than that in the comparative example. This difference will be described with reference to FIG.

7 is a diagram showing the return loss of the second filter 12 (or 552) in the frequency passband of the first filter 11. 7 (a), the first filter 11 and the second filter 12 are unbundled, and a circuit constituted by only the second filter 12 is used as the evaluation circuit corresponding to the embodiment Respectively. As the evaluation circuit corresponding to the comparative example, a circuit comprising only the second filter 552 of the comparative example was used.

7B is a diagram showing the return loss of each of the embodiment and the comparative example at 1850 MHz to 2050 MHz. As shown in Fig. 7 (b), in the comparative example, spurious waves having a large return loss are generated around 1975 MHz within the band of Band25Rx. This indicates that the signal input at 1975 MHz is not sufficiently reflected in the second filter 552 of the comparative example, and part of the signal is absorbed. In the comparative example, since this unnecessary wave exists in the vicinity of 1975 MHz, it is considered that the insertion loss in the vicinity of 1975 MHz is large as shown in Fig. 6 (b).

On the other hand, in the embodiment, the return loss is small in the band of Band25Rx. This is because the pitch lambda of the electrode finger of the IDT electrodes 211b to 215b is changed so that the position of the unwanted wave whose return loss of the second filter 12 is increased in the frequency pass band Band25Rx of the first filter 11 Is shifted out of the pass band. Specifically, the main pitch lambda m of the electrode fingers of the IDT electrodes 211b, 213b, and 215b connected to the second terminal 17 is set to be large or the electrode fingers of the IDT electrodes 212b and 214b connected to the common terminal 15 This is because the position of the spurious wave can be shifted to the higher frequency side than the pass band of the first filter 11 by reducing the main pitch lambda m of the finger. Thus, in the multiplexer 1A using the second filter 12 of the embodiment, it is possible to suppress the insertion loss from becoming large in the pass band of the first filter 11.

[6. theorem]

The multiplexer 1A according to the present embodiment has the common terminal 15, the first terminal 16 and the second terminal 17 and the path connecting the common terminal 15 and the first terminal 16 And a second filter (11) disposed on a path connecting the common terminal (15) and the second terminal (17) and having a higher passband frequency than the first filter (11) 12).

The second filter 12 is an acoustic wave filter and has a plurality of IDT portions 211 to 215 arranged along the propagation direction of an acoustic wave. Each of the plurality of IDT portions 211 to 215 is constituted by a set of IDT electrodes opposed to each other and of the plurality of IDT electrodes 211 to 215 constituting one of the plurality of IDT electrodes 212b and 214b Are connected to the common terminal 15 side of the common terminal 15 and the second terminal 17 and the other IDT electrodes 211b, 213b and 215b are connected to the common terminal 15 and the second terminal 17 17 are connected to the second terminal 17 side. Each of the IDT electrodes 212b and 214b and the other IDT electrodes 211b and 213b and 215b are formed on the surface of the piezoelectric substrate 326 and have a plurality of electrode fingers arranged in the propagation direction of the acoustic wave . The main pitches lambda m of the plurality of electrode fingers arranged in the propagation direction of the elastic wave are different from each other in the IDT electrodes 212b and 214b on one side and the IDT electrodes 211b and 213b on the other side, , 213b, and 215b have the largest main pitch lambda m of the electrode fingers among the plurality of IDT electrodes 211b to 215b.

According to this configuration, it is possible to move the position of the unwanted wave, which increases in the return loss of the second filter 12 occurring in the frequency passband of the first filter 11, out of the passband of the first filter 11. Thus, when the acoustic wave filter is used in the multiplexer 1A, it is possible to suppress the degradation of the passing characteristics of the other filters constituting the same multiplexer.

At least one of the IDT electrodes 212b and 214b may have a minimum main pitch lambda m of electrode fingers among the plurality of IDT electrodes 211b to 215b.

According to this configuration, the position of the unwanted wave whose return loss of the second filter 12 increases in the pass band of the first filter 11 is higher than the pass band of the first filter 11, It is possible to move it into the band of the stop band on the low frequency side of the antenna 12. Thus, when the acoustic wave filter is used in the multiplexer 1A, it is possible to suppress the degradation of the passing characteristics of the other filters constituting the same multiplexer.

The total average of the pitch lambda of the electrode fingers of one of the IDT electrodes 212b and 214b of the multiplexer 1A according to this embodiment is smaller than the average of the pitch lambda of the electrode fingers of the other IDT electrodes 211b, Is smaller than the total average of the pitch &lt; RTI ID = 0.0 &gt;

In the multiplexer 1A according to the present embodiment, when the average value of the pitch lambda of the electrode finger is obtained in each of the IDT electrodes 211b to 215b, the IDT electrode having the maximum average value is determined to be the other IDT electrode 211b, 213b, and 215b.

According to this configuration, it is possible to move the position of the unwanted wave, which increases in the return loss of the second filter 12 occurring in the frequency passband of the first filter 11, out of the passband of the first filter 11. Thus, when the acoustic wave filter is used in the multiplexer 1A, it is possible to suppress the degradation of the passing characteristics of the other filters constituting the same multiplexer.

(Other forms, etc.)

The multiplexers 1 and 1A according to the embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments. For example, the following modifications to the above embodiment may be included in the present invention.

8 is a circuit configuration diagram showing a high-frequency front end module 8 including a multiplexer 1B. In the high-frequency front end module 8 shown in Fig. 8, an LNA (LNA) is provided between the first terminal 16 and the RFIC 4 and between the second terminal 17 and the RFIC 4 in order to amplify the input signal. (Low Noise Amplifier) 3 are provided. Port switch 5 is provided between the first filter 11 and the common terminal 15 and between the second filter 12 and the common terminal 15 in order to switch the connection state with the antenna element 2, Respectively. When the first filter 11 is connected to the common terminal 15, that is, when the first filter 11 is performing signal processing The second filter 12 can also be connected to the common terminal 15. [

In the high-frequency front end module 8 having such a circuit configuration, in the case where the acoustic wave filter is used as a part of the multiplexer 1A as in the above-described embodiment, it is possible to suppress the degradation of the passing characteristics of other filters constituting the same multiplexer .

In the present embodiment, an example in which both the first filter 11 and the second filter 12 of the multiplexer 1A are reception filters is described. However, the present invention is not limited to this. Both of them may be transmission filters, It may be a receive filter and the other may be a transmit filter. Specifically, the band-pass filter of Band66Rx may be used as the second filter 12, and the band-pass filter of Band25Tx and Band66Tx may be used as the first filter 11. [ The band-pass filter of Band25Rx may be used as the second filter 12, and the band-pass filter of Band66Tx and Band25Tx may be used as the first filter 11. [ Alternatively, the band-pass filter of Band25Tx may be used as the second filter 12, and the band-pass filter of Band66Tx may be used as the first filter 11. [

Further, for example, the following modifications to the above embodiment may be included in the present invention.

Fig. 9 is a schematic plan view showing the configuration of a multiplexer according to another embodiment on the side of the second filter 12; Fig.

In the multiplexer according to this embodiment, the circuit element 350 is connected between the common terminal 15 and one of the IDT electrodes 212b and 214b of the second filter 12. Specifically, a circuit element 350 different from the second filter 12 is connected in series between the first port 230 and the common terminal 15. The circuit element 350 is, for example, an inductor, a capacitor, a switch, an LC resonator, or an acoustic wave resonator. For example, the LC resonator and the acoustic wave resonator may be a series resonator, a parallel resonator, or a resonator including both a series resonator and a parallel resonator. The circuit element 350 may be provided for frequency trapping or for impedance matching.

In the present invention, even when the circuit element 350 is connected between the IDT electrodes 212b and 214b and the common terminal 15 as described above, It is possible to move the position of the unnecessary wave whose return loss of the second filter 12 becomes large outside the pass band of the first filter 11. [ Thus, when the acoustic wave filter is used in the multiplexer 1A, it is possible to suppress the degradation of the passing characteristics of the other filters constituting the same multiplexer.

In the above-described embodiment, a surface acoustic wave filter having IDT electrodes is exemplified as the multiplexers 1 and 1A and the high-frequency front end module 8. However, each of the filters constituting the multiplexer 1, 1A and the high-frequency front end module 8 according to the present invention may be an acoustic wave filter using a boundary acoustic wave. This also provides the same effects as the effects of the multiplexer and the like according to the above embodiment.

The piezoelectric substrate 326 constituting the surface acoustic wave filter may be a laminated structure in which a high-sound-speed supporting substrate, a low-sound-attenuating film, and a piezoelectric film are laminated in this order. The piezoelectric film, such as 50 ° Y cut X-wide LiTaO _3, and the piezoelectric single crystal or piezoelectric ceramic (X axis as the central axis and a tantalate cut at the side of an axis 50 ° rotated from the Y axis to the normal lithium single crystal or a ceramic, X Single crystal or ceramics in which a surface acoustic wave propagates in the axial direction). The piezoelectric film has, for example, a thickness of 600 nm. The treble support substrate is a substrate for supporting the bass sound film, the piezoelectric film and the IDT electrode. The high-sound-speed support substrate is a substrate on which a sound velocity of a bulk wave in a high-sound-speed supporting substrate is higher than that of a surface wave or a boundary acoustic wave propagating through the piezoelectric film. The acoustic wave is confined in a portion where the piezoelectric film and the low- And functions so as not to leak downward from the treble support substrate. The high-sound speed supporting substrate is, for example, a silicon substrate and has a thickness of, for example, 200 mu m. The bass sound film is a film in which the sound velocity of the bulk wave in the bass sound film becomes lower than that of the acoustic wave propagating in the piezoelectric film, and is disposed between the piezoelectric film and the treble sound support substrate. The leakage of the surface acoustic wave energy out of the IDT electrode is suppressed by this structure and by the property that energy is concentrated in the medium in which the acoustic wave is essentially low. The bass film is, for example, a film mainly composed of silicon dioxide, and has a thickness of, for example, 670 nm. According to this laminated structure, the Q value at the resonance frequency and the anti-resonance frequency can be significantly increased as compared with the structure using the piezoelectric substrate 326 as a single layer. In other words, since a surface acoustic wave resonator having a high Q value can be formed, it is possible to construct a filter having a small insertion loss by using the surface acoustic wave resonator.

INDUSTRIAL APPLICABILITY The present invention can be widely applied to a communication device such as a cellular phone as a low-loss multiplexer and a high-frequency front-end module that can be applied to multiband and multi-mode frequency standards.

1, 1A, 1B: Multiplexer
2: Antenna element
3: LNA
4: RFIC (high frequency signal processing circuit)
5: Multiport switch
8: High-frequency front-end module
9: Communication device
11: first filter
12: second filter
15: Common terminal
16: first terminal
17: Second terminal
22: IDT section
22a and 22b: IDT electrodes
101, 103: transmission side filter
102, 104: Receiving filter
106, 108: transmission input terminal
107, 109: Receive output terminal
211, 212, 213, 214, 215: IDT portion
211b, 213b, and 215b: the other IDT electrode
212b and 214b: one IDT electrode
220, 221: reflector
221a and 221b: bus bar electrodes
222a, 222b: electrode finger
230: First port
240: second port
326: Piezoelectric substrate
350: circuit element
511, 512, 513, 514, 515: IDT portion (comparative example)
511b, 513b and 515b: one IDT electrode (comparative example)
512b and 514b: the other IDT electrode (comparative example)
552: Second filter (comparative example)
λ: pitch of electrode finger
? 1,? 2,? 3,? 4,? 5: the main pitch of the electrode finger

Claims (11)

A common terminal, a first terminal and a second terminal,
A first filter disposed on a path connecting the common terminal and the first terminal,
And a second filter disposed on a path connecting the common terminal and the second terminal and having a higher passband frequency than the first filter,
Wherein the second filter is an elastic wave filter and has a plurality of IDT portions arranged along the propagation direction of an acoustic wave,
Each of the plurality of IDT portions is composed of a set of IDT electrodes facing each other,
One of the plurality of IDT electrodes constituting the plurality of IDT portions is connected to the common terminal side of the common terminal and the second terminal and the other IDT electrode is connected to the common terminal and the second terminal A second terminal connected to the second terminal,
The one IDT electrode and the other IDT electrode are formed on the surface of the piezoelectric substrate and have a plurality of electrode fingers arranged in the propagation direction of the elastic wave,
The main pitch of the electrode finger is different between the one IDT electrode and the other IDT electrode,
And at least one of the other IDT electrodes has a maximum main pitch of the electrode finger among the plurality of IDT electrodes. The method according to claim 1,
Wherein at least one of the IDT electrodes has a minimum main pitch of the electrode finger among the plurality of IDT electrodes. A common terminal, a first terminal and a second terminal,
A first filter disposed on a path connecting the common terminal and the first terminal,
And a second filter disposed on a path connecting the common terminal and the second terminal and having a higher passband frequency than the first filter,
Wherein the second filter is an elastic wave filter and has a plurality of IDT portions arranged along the propagation direction of an acoustic wave,
Each of the plurality of IDT portions is composed of a set of IDT electrodes facing each other,
One of the plurality of IDT electrodes constituting the plurality of IDT portions is connected to the common terminal side of the common terminal and the second terminal and the other IDT electrode is connected to the common terminal and the second terminal A second terminal connected to the second terminal,
The one IDT electrode and the other IDT electrode are formed on the surface of the piezoelectric substrate and have a plurality of electrode fingers arranged in the propagation direction of the elastic wave,
The main pitch of the electrode finger is different between the one IDT electrode and the other IDT electrode,
Wherein the total average of the pitches of the electrode fingers of the one IDT electrode is smaller than the total average of the pitches of the electrode fingers of the other IDT electrode. A common terminal, a first terminal and a second terminal,
A first filter disposed on a path connecting the common terminal and the first terminal,
And a second filter disposed on a path connecting the common terminal and the second terminal and having a higher passband frequency than the first filter,
Wherein the second filter is an elastic wave filter and has a plurality of IDT portions arranged along the propagation direction of an acoustic wave,
Each of the plurality of IDT portions is composed of a set of IDT electrodes facing each other,
One of the plurality of IDT electrodes constituting the plurality of IDT portions is connected to the common terminal side of the common terminal and the second terminal and the other IDT electrode is connected to the common terminal and the second terminal A second terminal connected to the second terminal,
The one IDT electrode and the other IDT electrode are formed on the surface of the piezoelectric substrate and have a plurality of electrode fingers arranged in the propagation direction of the elastic wave,
The main pitch of the electrode finger is different between the one IDT electrode and the other IDT electrode,
And an average value of pitches of the electrode fingers is obtained in each of the IDT electrodes, an IDT electrode having the maximum average value exists in the other IDT electrode. 5. The method of claim 4,
Wherein an average value of the pitches of the electrode fingers is obtained in each of the IDT electrodes, and an IDT electrode having a minimum average value is present in the one IDT electrode. 6. The method according to any one of claims 1 to 5,
And a circuit element different from said second filter is connected between said one IDT electrode and said common terminal. 6. The method according to any one of claims 1 to 5,
The second filter has odd number of IDT portions of 3 or more,
The number of the IDT electrodes being smaller than the number of the other IDT electrodes. 6. The method according to any one of claims 1 to 5,
And the second filter has at least 5 IDT portions. 6. The method according to any one of claims 1 to 5,
Wherein the first filter and the second filter are mutually reception filters. 6. The method according to any one of claims 1 to 5,
And the second filter is connected to the common terminal when the first filter is connected to the common terminal. A high frequency front end module comprising the multiplexer according to any one of claims 1 to 5.

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