WO2003001668A1

WO2003001668A1 - Surface acoustic wave device

Info

Publication number: WO2003001668A1
Application number: PCT/JP2001/005422
Authority: WO
Inventors: Tsutomu Nagatsuka; Koji Ibata; Koichiro Misu; Kenji Yoshida
Original assignee: Mitsubishi Denki Kabushiki Kaisha
Priority date: 2001-06-25
Filing date: 2001-06-25
Publication date: 2003-01-03
Also published as: JPWO2003001668A1

Abstract

A surface acoustic wave device comprising a first surface acoustic wave filter (1) having a first passing band, a second surface acoustic wave filter (2) having a second passing band of higher frequency than the first passing band, and single terminal pair surface acoustic wave resonators (4) provided between the second surface acoustic wave filter (2) and first and second joints (31), (32), respectively. Good passing characteristics are realized entirely for a plurality of passing bands.

Description

Description Surface acoustic wave device Technical field

The present invention relates to a surface acoustic wave device, and more particularly to a surface acoustic wave device used for a high-frequency circuit of a mobile communication terminal or the like. Background art

Conventionally, surface acoustic wave devices have been widely used in mobile communication terminals typified by mobile phones because of their small size and high performance. In recent years, with the rapid increase in demand for mobile phones, mobile phone systems using a plurality of different frequency bands are being put into practical use. The high-frequency circuit section of the telephone used in such a system needs bandpass filters corresponding to each of these multiple bands. Furthermore, in order to reduce the size of telephones and the like, it is desirable to integrate filters having these multiple bands.

FIG. 14 is a diagram showing a conventional surface acoustic wave device of this type disclosed in, for example, Japanese Patent Application Laid-Open No. 9-284039. In the figure, 1 is the first surface acoustic wave filter, 2 is the second surface acoustic wave filter, 3 is the connection point, 5 is the inductor, 6 is the input terminal, 7 1 is the first output terminal, 7 2 is the second output terminal, and 14 is the capacity. In FIG. 14, the first surface acoustic wave filter 1 has a first pass band, and the second surface acoustic wave filter 2 has a second pass band. These two bands correspond to a plurality of bands in the mobile phone system, and the frequency of the second pass band is set higher than that of the first pass band. When an electric signal is input to the input terminal 6, if the frequency of the input electric signal is included in the first pass band, the electric signal passes through the first surface acoustic wave filter 1 and is output from the first output terminal 7 1 Is output. When the frequency of the electric signal is included in the second pass band, the signal passes through second surface acoustic wave filter 2 and is output from second output terminal 72. If the frequency of the electrical signal is not included in the first or second passband Since electric signals cannot pass through both the first surface acoustic wave filter 1 and the second surface acoustic wave filter 2, both the first output terminal 71 and the second output terminal 72 No output. Therefore, the surface acoustic wave device shown in Fig. 14 operates as a one-input, two-output dual band filter, in which the input electric signal is output to two different output terminals according to the two different frequency bands. I do.

In FIG. 14, both the capacitor 14 connected between the connection point 3 and the second surface acoustic wave filter 2 and the inductor 5 connected between the connection point 3 and the ground are This is for matching the input impedance in the pass band, and acts to reduce the insertion loss in the pass band.

In this type of conventional surface acoustic wave device, in order to reduce the effect of connecting one filter to the other in the pass band of one filter, the impedance of the other filter viewed from connection point 3 becomes infinite. It is desirable to be close.

The capacitor 14 is connected to increase the impedance of the second surface acoustic wave filter 2 in the first pass band, whereby the pass band of the first surface acoustic wave filter 1 is increased. This prevents deterioration of characteristics. When the capacitance 14 is connected, the impedance also changes in the second pass band, that is, in the pass band of the second surface acoustic wave filter 2 itself, so that the second surface acoustic wave is changed. The matching of the filter 2 itself deteriorates, causing an increase in insertion loss in the passband characteristics.

FIG. 15 is a diagram showing another configuration of this type of conventional surface acoustic wave device disclosed in, for example, Japanese Patent Application Laid-Open No. 11-41628. In the figure, 1 is a first surface acoustic wave filter, 2 is a second surface acoustic wave filter, 31 is a first connection point, 32 is a second connection point, 5 is an inductor, 6 is an input terminal, 7 is an output terminal, and 14 is a capacity terminal.

In FIG. 15, the first surface acoustic wave filter 1 has a first pass band.

The second surface acoustic wave filter 2 has a second pass band. These two bands correspond to a plurality of bands in the mobile phone system, and the frequency of the second pass band is set higher than that of the first pass band. The first surface acoustic wave filter 1 and the second surface acoustic wave filter 2 are connected to the first connection point 31. Input terminals are connected to each other, and output terminals are connected to each other at a second connection point 32.

In the surface acoustic wave device shown in FIG. 15, not only the input terminal 6 but also the output terminal 7 are shared. Therefore, when an electric signal is input to the input terminal 6, the signal of the frequency of the first pass band and the signal of the frequency of the second pass band are both output from the output terminal 7. Therefore, it operates as a one-input, one-output dual band filter in which signals of two different frequency bands are output to the same output terminal.

In the conventional example shown in FIG. 15 as well, a capacitor 14 and an inductor 5 are used to match the impedance.

In this one-input one-output surface acoustic wave device, the impedance of one filter at the pass band of the other filter is infinite at both the first connection point 31 and the second connection point 32. It needs to be very close.

By connecting the capacity 14 inductor 5 in series with the surface acoustic wave filter, the impedance in the pass band of the other surface acoustic wave filter can be brought close to a required value. However, at the same time, the impedance changes in the own pass band, and the pass band characteristics deteriorate, such as an increase in loss.

As described above, in this type of conventional surface acoustic wave device, since the capacitors 14 and the inductor 5 are used as the matching circuits, there is a problem that the passband characteristics are deteriorated.

Therefore, the present invention is to provide a surface acoustic wave device that operates as a one-input one-output filter capable of improving all the pass characteristics of a plurality of passbands. Disclosure of the invention

The present invention provides a first surface acoustic wave filter having a first pass band, a second surface acoustic wave filter having a second pass band having a higher frequency than the first pass band, A first connection point electrically connecting the input terminal of the first surface acoustic wave filter and the input terminal of the second surface acoustic wave filter to each other; and the first surface acoustic wave filter. Output terminal and the output terminal of the second SAW filter A second connection point electrically connected to the second surface acoustic wave filter, the first connection point, and the second surface acoustic wave filter and the second connection point. A surface acoustic wave device comprising a one-terminal pair surface acoustic wave resonator provided between the two. Therefore, it is possible to suppress the deterioration of the pass characteristics in the pass band and to realize good pass characteristics in all of the plurality of pass bands.

Also, the present invention provides a first ground provided on the first connection point side, a second ground provided on the second connection point side, the first connection point and the first ground. And a second inductor connected to the second connection point and the second ground. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a configuration diagram showing a surface acoustic wave device according to Embodiment 1 of the present invention,

FIG. 2 is a configuration diagram showing the first and second surface acoustic wave filters in FIG. 1, FIG. 3 is an explanatory diagram showing pass frequency characteristics of the first and second surface acoustic wave filters in FIG. 1,

FIG. 4 is an explanatory diagram showing impedance characteristics of the first and second surface acoustic wave filters in FIG. 1,

FIG. 5 is a configuration diagram showing the one-port surface acoustic wave resonator in FIG. 1,

Fig. 6 is an explanatory diagram showing the impedance characteristics of the one-port surface acoustic wave resonator of Fig. 5. Fig. 7 is a one-port versus surface acoustic wave at the input terminal of the second surface acoustic wave filter in Fig. 1. FIG. 8 is an explanatory diagram showing how the impedance value changes in the first pass band when resonators are connected in series. FIG. 8 shows the pass frequency characteristics of the surface acoustic wave device according to the first embodiment of the present invention. Explanatory diagram,

FIG. 9 is an explanatory diagram showing a pass frequency characteristic when two filters are directly connected without using the one-port surface acoustic wave resonator in the configuration of FIG. 1,

FIG. 10 is a configuration diagram illustrating a surface acoustic wave device according to Embodiment 2 of the present invention. FIG. 11 is a diagram illustrating a VS WR (voltage standing wave ratio) viewed from an input terminal in the configuration of FIG. Explanatory diagram showing the frequency characteristics of

FIG. 12 is an explanatory diagram showing a pass frequency characteristic of the surface acoustic wave device according to Embodiment 2 of the present invention,

FIG. 13 is a configuration diagram illustrating a surface acoustic wave device according to Embodiment 3 of the present invention. FIG. 14 is a configuration diagram illustrating a conventional surface acoustic wave device.

FIG. 15 is a configuration diagram showing another conventional surface acoustic wave device. BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1

FIG. 1 is a diagram showing a surface acoustic wave device according to Embodiment 1 of the present invention. In the figure, 1 is the first surface acoustic wave filter, 2 is the second surface acoustic wave filter, 3 1 is the first connection point, 3 2 is the second connection point, and 4 is 1 terminal pair elastic surface. A surface acoustic wave resonator, 6 is an input terminal, and 7 is an output terminal.

In FIG. 1, a first surface acoustic wave filter 1 is a band pass filter having a first pass band, and a second surface acoustic wave filter 2 is a band pass filter having a second pass band. . The first surface acoustic wave filter 1 and the second surface acoustic wave filter 2 have their input terminals and output terminals connected at a first connection point 31 and a second connection point 32, respectively. ing. Also, between the input terminal of the second surface acoustic wave filter 2 and the first connection point 31 and the output terminal of the second surface acoustic wave filter 2 and the second connection point 32 Each terminal is connected to one terminal pair surface acoustic wave resonator 4.

FIG. 2 is a diagram showing a configuration of each of the first surface acoustic wave filter 1 and the second surface acoustic wave filter 2 in FIG. In the figure, 8 is an interdigital electrode, 9 is a reflector, 10 is an input terminal, and 11 is an output terminal. As shown in FIG. 2, the first surface acoustic wave filter 1 and the second surface acoustic wave filter 2 in FIG. 1 are composed of three interdigital electrodes 8 and two reflectors 9 on both sides thereof. Have been. The center interdigital electrode 8 is connected to the input terminal 10, and the two interdigital electrodes 8 on both sides are connected to the output terminal 11. This configuration is called a so-called three-electrode double-mode resonator filter. In FIG. 2, when an electric signal of a specific frequency is input to the input terminal 10, the electric signal is converted into a surface acoustic wave by the center interdigital electrode 8. The surface acoustic waves are reflected by the reflectors 9 on both sides, and are multiple-reflected between the reflectors 9 on both sides, so-called resonance occurs. A part of the resonating surface acoustic wave is converted into an electric signal again at the IDTs 8 on both sides, and is output from the output terminal 11. At such a frequency at which resonance occurs, the energy of the surface acoustic wave is efficiently confined between the reflectors 9 on both sides, and almost no loss occurs. At a frequency where resonance does not occur, the surface acoustic wave is hardly reflected by the reflector 9, so that even if an electric signal is input to the input terminal 10, the electric signal is hardly output from the output terminal 11. Therefore, the surface acoustic wave filter shown in Fig. 2 has a specific passband and operates as a bandpass filter with a small loss in that passband.

Note that the first surface acoustic wave filter 1 in FIG. 1 has, for example, a center interdigital electrode 8 of 23 pairs, an interdigital electrode 8 of 17.5 pairs each, and an intersection width of an elastic surface. The wave wavelength is 15 wavelengths. The second surface acoustic wave filter 2 in FIG. 1 has 13 pairs of interdigital electrodes 8 in the center, 9 pairs of interdigital electrodes 8 on both sides, and a cross width of 95 wavelengths.

FIG. 3 is a diagram showing the pass frequency characteristics of the first surface acoustic wave filter 1 and the second surface acoustic wave filter 2 in FIG. 1 by themselves. The pass characteristics of the first surface acoustic wave filter 1 are indicated by solid lines, and the pass characteristics of the second surface acoustic wave filter 2 are indicated by broken lines. The pass band of the first surface acoustic wave filter 1, that is, the first pass band is set to 893 to 8998 MHz. The pass band of the second surface acoustic wave filter 2, that is, the second pass band is set to 925 MHz to 960 MHz. Therefore, the second pass band is set higher than the first pass band.

In FIG. 1, the first surface acoustic wave filter 1 and the second surface acoustic wave filter 2 are connected by input terminals and output terminals, respectively. At this time, in order for the insertion loss in the pass band of each surface acoustic wave filter to be as low as the characteristic of the single device, it is necessary to look at the connection point at the frequency of the pass band of one surface acoustic wave filter. The absolute value of the impedance of the other surface acoustic wave It must be.

Fig. 4 shows the impedance characteristics of the first surface acoustic wave filter 1 and the second surface acoustic wave filter 2 shown in Fig. 1 on a Smith chart. FIG. 4 (a) shows the input impedance of the first surface acoustic wave filter 1 and FIG. 4 (b) shows the input impedance of the second surface acoustic wave filter 2. The point indicated by A in the figure is a point corresponding to the pass band of the first surface acoustic wave filter 1, that is, the frequency of the first pass band. A point indicated by B is a pass band of the second surface acoustic wave filter 2, that is, a point corresponding to the frequency of the second pass band. Also, it is well known that the Smith chart means that the impedance increases as approaching the right end point in the figure, and that the impedance decreases as approaching the left end point in the figure.

The impedance shown at point B in Fig. 4 (a), that is, the input impedance in the second passband of the first surface acoustic wave filter, is near the right end of the Smith chart, and the absolute values of the impedances It has a very large value. However, the impedance shown at point A in Fig. 4 (b), that is, the input impedance in the first passband of the second surface acoustic wave filter 2, is at a location far from the right end of the Smith chart and near the left end. It is in. Therefore, the absolute value of the impedance at this point is relatively small. The impedance value at the frequency of point A is equivalent to 8.7 pF in capacitance.

If these two surface acoustic wave filters are directly connected, the input impedance in the first passband of the second elastic surface wave filter 2 is small, and therefore the first elastic surface wave filter 1 It is expected that the matching in the band will be lost and the insertion loss in the first pass band will be degraded. .

FIG. 5 is a diagram showing a configuration of the one-terminal surface acoustic wave resonator 4 in FIG. In the figure, 8 is an interdigital electrode, 9 is a reflector, and 12 is an electrical terminal. It comprises an interdigital electrode 8 and two reflectors 9 on both sides thereof, and the interdigital electrode 8 is connected to the electric terminals 12.

In FIG. 5, when an electric signal is applied to the electric terminal 12, the electric signal is converted into a surface acoustic wave by the interdigital electrode 8. When this surface acoustic wave is at a specific frequency, Multiple reflection is caused by the reflector 9 on the side, and resonance occurs. In the vicinity of the frequency at which this resonance occurs, the impedance between the electrical terminals 12 rapidly changes depending on the frequency. In the one-terminal surface acoustic wave resonator 4 in FIG. 1, the IDTs 8 are paired with 100, and the cross width is 16 wavelengths.

FIG. 6 is a diagram illustrating impedance characteristics of the single-port surface acoustic wave resonator 4 of FIG. 5 alone. The horizontal axis represents the frequency, and the vertical axis represents the imaginary part of the impedance, that is, the reactance component. The real part of the impedance, that is, the resistance component, is very small in value as compared with the reaction component, and is omitted here. At the frequency indicated by point B in the figure, the impedance is almost zero. This frequency is called the resonance frequency. At the frequency indicated by point C in the figure, which is slightly higher than the resonance frequency, the impedance is almost infinite. This frequency is called the anti-resonance frequency o

At the frequency indicated by point A in the figure, which is lower than the resonance frequency point B, the reactance has a negative value, which is a capacitive impedance.

Now, if the resonance frequency point B is approximately matched with the pass band of the second surface acoustic wave filter 2 shown in FIG. 4 (b), that is, the second pass band, The impedance is approximately zero in the second pass band and capacitive in the first pass band. The impedance at the frequency of point A is equivalent to 4.9 pF in capacitance.

Figure 7 shows that the input terminal of the second surface acoustic wave filter 2 has a one-terminal pair surface acoustic wave resonator.

4 shows how impedance values change in a first pass band when 4 are connected in series. Point A is the input impedance of the second surface acoustic wave filter 2 alone as shown in FIG. 4 (b). By connecting the one-port surface acoustic wave resonator 4, the impedance moves from point A to point A,. In other words, approaching the right end of the Smith chart, the absolute value of the impedance increases. At this time, in the second pass band, since the impedance of the one-port surface acoustic wave resonator 4 is almost zero, the position of the point B shown in FIG. Almost no change after connecting device 4.

As described above, the first surface acoustic wave filter 1 and the second surface acoustic wave filter 2 When the connection is made at the connection point, the one-port pair surface acoustic wave resonator 4 is connected in series to the second surface acoustic wave filter 2, so that the impedance of oneself in the pass band of one surface acoustic wave filter The impedance of the other surface acoustic wave filter can be increased to each other without greatly changing the impedance. Therefore, low loss characteristics can be realized in both the first pass band and the second pass band without deterioration of insertion loss at the time of connection.

The impedance of the one-port surface acoustic wave resonator 4 is close to infinity at the anti-resonance frequency indicated by point C in FIG. This frequency will be higher than the second passband. If an impedance close to infinity is connected in series, the electric signal will not be passed and the attenuation will increase. Therefore, connecting the one-terminal surface acoustic wave resonator 4 also has the effect of increasing the amount of out-of-band attenuation at frequencies higher than the second passband.

FIG. 8 shows transmission frequency characteristics of the surface acoustic wave device having the configuration of FIG. 1 showing the first embodiment of the present invention. The minimum insertion loss in the first pass band is 3.5 dB, and the minimum insertion loss in the second pass band is 1.9 dB.

Note that FIG. 9 shows, for comparison, the pass frequency characteristics when two filters are directly connected without using the one-port surface acoustic wave resonator 4 in the configuration of FIG. Although the insertion loss in the second pass band is small, the minimum insertion loss in the first pass band is 9.2 dB, which is very large. The out-of-band attenuation near 106 MHz is also worse than that in FIG.

As described above, in the first embodiment of the present invention, the one-terminal-pair surface acoustic wave resonator 4 is connected in series to the second surface acoustic wave filter 2, thereby having a plurality of low-loss transmission characteristics. However, there is an effect that a surface acoustic wave device having good out-of-band attenuation can be obtained. In the present embodiment, the case where a so-called three-electrode type double mode resonator filter is used as the first surface acoustic wave filter 1 and the second surface acoustic wave filter 2 has been described. The present invention is not limited to this, and other surface acoustic wave filters such as a so-called ladder-type filter having similar input impedance characteristics may be used, and similar effects can be obtained. Embodiment 2

FIG. 10 is a diagram showing a surface acoustic wave device according to Embodiment 2 of the present invention. In the figure, 1 is the first surface acoustic wave filter, 2 is the second surface acoustic wave filter, 3 1 is the first connection point, 3 2 is the second connection point, and 4 is 1 port to surface acoustic wave. Resonator, 5 is an inductor, 6 is an input terminal, and 7 is an output terminal.

In FIG. 10, the first surface acoustic wave filter 1 is a band-pass filter having a first pass band, and the second surface acoustic wave filter 2 is a second pass filter having a higher pass band than the first pass band. Is a bandpass filter having a pass band of The first surface acoustic wave filter 1 and the second surface acoustic wave filter 2 have their input terminals and output terminals connected at the first connection point 31 and the second connection point 32, respectively. It is connected. In addition, the input terminal of the second surface acoustic wave filter 2 and the first connection point 31 and the output terminal of the second surface acoustic wave filter 2 and the second connection point 32 It is connected to one terminal pair surface acoustic wave resonator 4. Further, the inductor 5 is connected between the first connection point 31 and the ground, and between the second connection point 32 and the ground.

The configuration of the first surface acoustic wave filter 1 and the second surface acoustic wave filter 2 in FIG. 10 is the same as that shown in FIG. 2 of the first embodiment. Also, the one-port surface acoustic wave resonator 4 in FIG. 10 is the same as that shown in FIG. 5 of the first embodiment.

In FIG. 10, as in the first embodiment, a one-terminal-pair elastic surface wave resonator 4 is connected to the second surface acoustic wave filter 2 in series. Therefore, as shown at point A ′ in FIG. 7, the absolute value of the impedance of the second surface acoustic wave filter 2 in the first pass band can be increased. However, even in this respect, the impedance is not completely infinite, but remains as a capacitive impedance. The impedance at the point A, is equivalent to 3 · lpF in terms of capacitance.

In FIG. 10, an inductor 5 is further connected between the connection point and the ground. The inductance of the inductor 5 is 1 On H. By connecting Inductor 5 in parallel, capacitive impedance and inductive impedance can be connected in parallel. Due to resonance, the impedance can be made closer to infinity. Figure 11 shows the frequency characteristics of VS WR (voltage standing wave ratio) viewed from the input terminal. The solid line shows the characteristics when the inductor 5 shown in FIG. 10 is connected, and the broken line shows the characteristics when the inductor 5 is not connected for comparison. By connecting the inductor 5, it can be seen that the VS WR is reduced in both the first pass band and the second pass band, and the matching is better.

FIG. 12 shows a pass frequency characteristic of the surface acoustic wave device having the configuration of FIG. 10 showing the second embodiment of the present invention. The minimum insertion loss in the first pass band is 2.5 dB, and the minimum insertion loss in the second pass band is 1.5 dB. Compared to the characteristics when inductor 5 is not connected as shown in Fig. 8, both the first pass band and the second pass band have even lower loss characteristics, and the characteristics within the band are also flat. . In addition, since the one-port resonator 4 is connected, the out-of-band attenuation near the anti-resonance frequency of 106 MHz is as good as in FIG.

As described above, in the second embodiment of the present invention, the one-port surface acoustic wave resonator 4 is connected in series to the second surface acoustic wave filter 2, and the inductor 5 is connected in parallel. Thus, there is an effect that a surface acoustic wave device having a plurality of lower loss passbands and a good out-of-band attenuation can be obtained. Embodiment 3.

FIG. 13 is a diagram showing a surface acoustic wave device according to Embodiment 3 of the present invention. In the figure, 1 is the first surface acoustic wave filter, 2 is the second surface acoustic wave filter, 3 1 is the first connection point, 3 2 is the second connection point, and 4 is 1 port to surface. The wave resonator, 5 is an inductor, 6 is an input terminal, 7 is an output terminal, and 13 is a package.

The configuration of FIG. 13 is substantially the same as the configuration of the second embodiment shown in FIG.

. However, in FIG. 13, the first surface acoustic wave filter 1, the second surface acoustic wave filter 2, and the one-port surface acoustic wave resonator 4 are housed in the same package 13. I have. As an electrical element, Inductor 5 generally has a feature that its size is slightly larger than other elements. For this reason, here, the chip inductor 5 is used for the chip inductor 5 and is externally attached to the package 13. With this configuration, The surface acoustic wave device can be downsized when it is actually mounted on a circuit board of a mobile phone or the like.

The package 13 may be formed of metal, ceramic, or an organic material such as plastic, and may be a composite of these materials. May be used. Further, the one-port surface acoustic wave resonator 4 can be formed on the same substrate as the first surface acoustic wave filter 1 or the second surface acoustic wave filter 2. The substrate is not particularly limited as long as it is made of a material capable of transmitting a surface acoustic wave, and is generally used for this type of surface acoustic wave device, such as lithium niobate, lithium tantalate, crystal, and langasite. Various substrates can be used.

Further, the first surface acoustic wave filter 1 and the second surface acoustic wave filter 2 can be formed on the same substrate. However, in this case, if the first pass band and the second pass band are far apart, it may be necessary to change the metal thickness of the electrode pattern optimal for each filter. It is possible to fabricate patterns with different thicknesses on the same substrate, but the same thickness makes fabrication easier. For this purpose, it is preferable that the frequency ratio between the first pass band and the second pass band be within 1.5, which facilitates the manufacture of the surface acoustic wave device.

As described above, in the third embodiment of the present invention, the first surface acoustic wave filter 1, the second surface acoustic wave filter 2, and the one-port surface acoustic wave resonator 4 have the same package 13 By storing the surface acoustic wave device inside, it is possible to obtain a small and highly productive surface acoustic wave device having a plurality of pass bands. Industrial applicability

As described above, the surface acoustic wave device according to the present invention has a plurality of surface acoustic wave filters having different pass bands, and one terminal pair surface acoustic wave resonator is serially connected to one of the surface acoustic wave filters. By connecting, the pass characteristics of a plurality of pass bands can all be improved, and the out-of-band attenuation can be improved. Therefore, by using the surface acoustic wave device of the present invention for a mobile communication terminal using a plurality of different frequency bands, which is being developed in response to a rapid increase in demand for a mobile phone, etc. This is effective for improving the communication accuracy of the communication terminal, and also leads to the improvement of the high performance and miniaturization of the mobile communication terminal.

Claims

The scope of the claims

1. a first surface acoustic wave filter having a first passband;

A second surface acoustic wave filter having a second pass band having a higher frequency than the first pass band;

A first connection point electrically connecting the input terminal of the first surface acoustic wave filter and the input terminal of the second surface acoustic wave filter to each other;

A second connection point electrically connecting the output terminal of the first surface acoustic wave filter and the output terminal of the second surface acoustic wave filter to each other;

A one-terminal-pair surface acoustic wave resonator provided between the second surface acoustic wave filter and the first connection point, and between the second surface acoustic wave filter and the second connection point When

A surface acoustic wave device comprising:

2. The first ground provided on the first connection point side,

A second ground provided on the second connection point side;

And an inductor connected between the first connection point and the first ground, and between the second connection point and the second ground.

The surface acoustic wave device according to claim 1, further comprising:

3. The first surface acoustic wave filter, the second surface acoustic wave filter, and the one-port surface acoustic wave resonator are housed in the same package. 3. The surface acoustic wave device according to 1 or 2.

4. The first surface acoustic wave filter or the second surface acoustic wave filter and the one-port surface acoustic wave resonator are made of the same material made of a material through which surface acoustic waves can propagate. 4. The surface acoustic wave device according to claim 1, wherein the surface acoustic wave device is arranged on a substrate.

5. The ratio of the frequency of the second pass band to the frequency of the first pass band is greater than 1 and less than 1.5. A surface acoustic wave device according to claim 1.