JP6747387B2 - High frequency module - Google Patents

Description

The present invention relates to a high frequency module.

Conventionally, a high frequency module using a surface acoustic wave (SAW) filter has been developed as a circuit module of a mobile communication device. With the widening of communication frequency band in recent years, there is an increasing demand for low loss and low noise in the receiving circuit module in order to improve the receiving sensitivity of the high frequency module. Therefore, the high-frequency module is provided with other components at the rear stage or the front stage of the surface acoustic wave filter (see, for example, Patent Document 1).

In the high frequency module described in Patent Document 1, a low noise amplifier (LNA) is connected downstream of the surface acoustic wave filter. Generally, in order to improve the noise characteristics in a high frequency module, the impedance (output impedance) at the output end of the surface acoustic wave filter on the side connected to the low noise amplifier is ), the output impedance of the surface acoustic wave filter is adjusted.

The output impedance of the surface acoustic wave filter is generally adjusted by changing the crossing width of the IDT (Inter Digital Transducer) electrode in the resonator forming the surface acoustic wave filter or the number of pairs of electrode fingers in the IDT electrode. It is being appreciated.

JP, 2008-301223, A

However, when the output impedance of the surface acoustic wave filter is adjusted by changing the crossing width of the IDT electrode, when the crossing width is large, the resistance of the electrode fingers forming the IDT electrode becomes large, resulting in a large signal loss. Further, when the crossing width is small, diffraction loss occurs in the IDT electrode, resulting in a large signal loss. Therefore, when the cross width of the IDT electrode is changed to reduce the noise of the surface acoustic wave filter, it is difficult to reduce the loss of the high frequency module.

Further, when the output impedance of the surface acoustic wave filter is adjusted by changing the number of pairs of electrode fingers in the IDT electrode, when the number of pairs of electrode fingers is large, the interval of the resonance mode necessary for forming the frequency band of the surface acoustic wave filter. Is narrowed, the pass band width of the surface acoustic wave filter is narrowed. Further, when the number of pairs of electrode fingers is small, the interval between the resonance modes becomes wide, the characteristics of the voltage standing wave ratio (VSWR) deteriorate, and the signal loss increases. Therefore, even when the number of pairs of electrode fingers in the IDT electrode is changed to reduce the noise of the surface acoustic wave filter, it is difficult to reduce the loss of the high frequency module.

In view of the above problems, it is an object of the present invention to provide a high frequency module that can realize both low loss and low noise.

In order to achieve the above object, one aspect of a high-frequency module according to the present invention is a longitudinally coupled surface acoustic wave filter including a plurality of resonators, and the surface acoustic wave filter is connected to the surface acoustic wave filter. A low noise amplifier for amplifying the passed high frequency signal, wherein the input impedance and the output impedance of the surface acoustic wave filter connected to the low noise amplifier are different, and in the Smith chart, the passage of the surface acoustic wave filter. The output impedance in the band is the first output impedance which is the output impedance of the surface acoustic wave filter when the gain of the low noise amplifier is maximum and the output impedance when the noise figure of the low noise amplifier is minimum. It exists in a region between the output impedance of the surface acoustic wave filter and the second output impedance.

Thus, in the Smith chart, between the output impedance of the surface acoustic wave filter when the gain of the low noise amplifier is maximum and the output impedance of the surface acoustic wave filter when the noise figure of the low noise amplifier is minimum. Since the output impedance of the surface acoustic wave filter is adjusted, it is possible to realize both low loss and low noise of the surface acoustic wave filter and the high frequency module.

Further, the surface acoustic wave filter may have an electrode parameter for adjusting the output impedance in the pass band of the surface acoustic wave filter to the region on the Smith chart.

As a result, by adjusting the electrode parameters in the surface acoustic wave filter, both low loss and low noise can be realized.

Further, at least one IDT electrode of the resonator connected to the output terminal of the surface acoustic wave filter may include a thinning electrode, and the electrode parameter may be the number of the thinning electrodes.

Accordingly, by adjusting the number of thinning electrodes, the capacitive impedance of the resonator in which the thinning electrodes are formed can be adjusted. Therefore, the output impedance of the surface acoustic wave filter can be adjusted.

Further, the thinning electrode may be provided in a central portion of the resonator.

Accordingly, by providing the thinned electrode in the central portion of the resonator, which has less influence on the resonance mode, it is possible to reduce the loss of the surface acoustic wave filter.

Further, the thinning electrode may be provided in a range of 46% of a central portion of the resonator.

Accordingly, by providing the thinned electrode in a predetermined region of the central portion of the resonator, which has a small effect on the resonance mode, it is possible to further reduce the loss of the surface acoustic wave filter.

Further, the IDT electrode of the resonator connected to the output terminal of the surface acoustic wave filter is divided in the cross width direction, and the electrode parameter is the number of divisions of the IDT electrode in the cross width direction. Good.

As a result, the output impedance of the surface acoustic wave filter can be adjusted without being affected by the diffraction loss of the resonator obtained by dividing the IDT electrode.

The electrode parameter is a first main wavelength that is an average value of main wavelengths of the resonators connected to an input terminal of the surface acoustic wave filter, and the electrode connected to an output terminal of the surface acoustic wave filter. It is a second main wavelength that is an average value of main wavelengths in the resonator, and the first main wavelength and the second main wavelength may be different.

As a result, the output impedance of the surface acoustic wave filter can be changed from 50Ω. Therefore, the output impedance of the surface acoustic wave filter can be changed to match the impedances of the surface acoustic wave filter and the low noise amplifier.

Further, the electrode parameter is connected to an output terminal of the surface acoustic wave filter for a first main wavelength that is an average value of main wavelengths of the resonators connected to an input terminal of the surface acoustic wave filter. The main wavelength ratio is a ratio of a second main wavelength that is an average value of main wavelengths in the resonator, and the main wavelength ratio may be 1.01 or more.

Thereby, the output impedance of the surface acoustic wave filter can be made higher than 50Ω. Therefore, the impedances of the surface acoustic wave filter and the low noise amplifier can be more matched.

The electrode parameter is a main duty of the resonator connected to the output terminal of the surface acoustic wave filter, and the main duty may be larger than 0.55 and smaller than 0.75.

Thus, the output impedance of the surface acoustic wave filter can be increased or decreased by increasing or decreasing the main duty of the resonator connected to the output terminal of the surface acoustic wave filter. Further, since the output impedance of the surface acoustic wave filter can be changed from 50Ω, the output impedance of the surface acoustic wave filter can be changed to match the impedances of the surface acoustic wave filter and the low noise amplifier.

Further, in the surface acoustic wave filter, the wiring between the IDT electrode of the resonator connected to the output terminal of the surface acoustic wave filter and the output terminal of the surface acoustic wave filter is formed on a substrate. It may be formed on the interlayer insulating film.

As a result, the output impedance of the surface acoustic wave filter can be adjusted to an inductive impedance by reducing the capacitive coupling between the wiring and the substrate.

The IDT electrode of the resonator connected to the output terminal of the surface acoustic wave filter has a first electrode layer formed on a substrate and a second electrode layer formed on the first electrode layer. The wiring may include an electrode layer, and the wiring at a position where the interlayer insulating film is arranged may be configured by the first electrode layer and the second electrode layer.

As a result, the reduction in the capacitive coupling between the wiring and the substrate is small, so that the output impedance of the surface acoustic wave filter can be adjusted to the inductive impedance with a small adjustment amount.

Further, the wiring at the position where the interlayer insulating film is arranged may have the interlayer insulating film instead of the first electrode layer.

As a result, the capacitive coupling between the wiring and the substrate can be further reduced, so that the output impedance of the surface acoustic wave filter can be adjusted to a more inductive side.

According to the present invention, it is possible to provide a high-frequency module capable of realizing both low loss and low noise.

3 is a conceptual diagram showing the configuration of the high-frequency module according to the first embodiment. FIG. 1 is a schematic diagram showing a configuration of a surface acoustic wave filter according to a first exemplary embodiment. FIG. 2B is a schematic diagram showing the basic configuration of the surface acoustic wave filter shown in FIG. 2A. It is the schematic which shows the structure of a general surface acoustic wave filter, (a) is a top view, (b) is an arrow sectional drawing in the dashed-dotted line shown to (a). FIG. 3 is a schematic diagram showing details of the configuration of the surface acoustic wave filter according to the first exemplary embodiment. FIG. 3 is a schematic diagram showing a configuration of a resonator when the number of thinning electrodes is one in the surface acoustic wave filter according to the first exemplary embodiment. FIG. 4 is a schematic diagram showing a configuration of a resonator when the number of thinned electrodes is two in the surface acoustic wave filter according to the first exemplary embodiment. FIG. 3 is a schematic diagram showing a configuration of a resonator when the number of thinning electrodes is three in the surface acoustic wave filter according to the first exemplary embodiment. FIG. 3 is a diagram showing reflection characteristics on the output terminal side of the surface acoustic wave filter according to the first exemplary embodiment. FIG. 4 is a schematic diagram showing a configuration of a resonator for explaining positions where thinning electrodes are provided in the surface acoustic wave filter according to the first exemplary embodiment. FIG. 4 is a diagram showing a relationship between positions where thinning electrodes are provided and signal loss on the output terminal side of the surface acoustic wave filter in the surface acoustic wave filter according to the first exemplary embodiment. FIG. 5 is a diagram for explaining a method of adjusting the output impedance of the surface acoustic wave filter according to the first exemplary embodiment. FIG. 6 is a diagram showing a pass characteristic of the surface acoustic wave filter when the output impedance of the surface acoustic wave filter according to the first exemplary embodiment is adjusted. FIG. 5 is a diagram showing reflection characteristics on the output terminal side of the surface acoustic wave filter when the output impedance of the surface acoustic wave filter according to the first exemplary embodiment is adjusted. FIG. 5 is a diagram showing a pass characteristic of the high frequency module when the output impedance of the surface acoustic wave filter according to the first exemplary embodiment is adjusted. FIG. 6 is a schematic diagram showing a configuration of a surface acoustic wave filter according to a second exemplary embodiment. FIG. 6 is a schematic diagram showing a configuration of a resonator in the surface acoustic wave filter according to the second exemplary embodiment. FIG. 7 is a diagram showing reflection characteristics on the output terminal side of the surface acoustic wave filter according to the second exemplary embodiment. FIG. 9 is a diagram showing pass characteristics on the output terminal side of the surface acoustic wave filter according to the second exemplary embodiment. FIG. 8 is a diagram showing noise characteristics on the output terminal side of the entire high frequency module having the surface acoustic wave filter according to the second embodiment. FIG. 6 is a schematic diagram showing a configuration of a surface acoustic wave filter according to a third exemplary embodiment. FIG. 9 is a diagram showing reflection characteristics on the output terminal side of the surface acoustic wave filter according to the third exemplary embodiment. FIG. 9 is a diagram showing pass characteristics on the output terminal side of the surface acoustic wave filter according to the third exemplary embodiment. FIG. 7 is a schematic diagram showing another configuration of the surface acoustic wave filter according to the third exemplary embodiment. FIG. 11 is a diagram showing reflection characteristics on the output terminal side of a surface acoustic wave filter having another configuration according to the third exemplary embodiment. FIG. 11 is a diagram showing pass characteristics on the output terminal side of a surface acoustic wave filter having another configuration according to the third exemplary embodiment. FIG. 9 is a schematic diagram showing a configuration of a surface acoustic wave filter according to a fourth embodiment. It is a figure which shows the reflection characteristic by the side of the output terminal of the surface acoustic wave filter concerning Embodiment 4. It is a figure which shows the passage characteristic by the side of the output terminal of the surface acoustic wave filter concerning Embodiment 4. FIG. 9 is a schematic diagram showing another configuration of the surface acoustic wave filter according to the fourth embodiment. It is a figure which shows the reflection characteristic by the side of the output terminal of the surface acoustic wave filter concerning Embodiment 4. It is a figure which shows the passage characteristic by the side of the output terminal of the surface acoustic wave filter concerning Embodiment 4. FIG. 9 is a schematic diagram showing a configuration of a surface acoustic wave filter according to a fifth embodiment. It is sectional drawing which shows the structure in the BB line of the surface acoustic wave filter shown in FIG. It is sectional drawing which shows the structure in the CC line of the surface acoustic wave filter shown in FIG. FIG. 16 is a diagram showing reflection characteristics on the output terminal side of a surface acoustic wave filter having another configuration according to the fifth embodiment. FIG. 16 is a diagram showing noise characteristics on the output terminal side of the surface acoustic wave filter according to the fifth embodiment. It is sectional drawing which shows the other structure in CC line of the surface acoustic wave filter shown in FIG.

Hereinafter, embodiments of the present invention will be described. It should be noted that each of the embodiments described below shows a preferred specific example of the present invention. Therefore, numerical values, shapes, materials, constituent elements, arrangement positions of constituent elements, connection forms, and the like shown in the following embodiments are merely examples and are not intended to limit the present invention. Therefore, among the constituent elements in the following embodiments, the constituent elements that are not described in the independent claims showing the highest concept of the present invention are described as arbitrary constituent elements.

In addition, each drawing is a schematic view and is not necessarily strictly illustrated. In each drawing, substantially the same components are designated by the same reference numerals, and duplicate description will be omitted or simplified. Further, in the illustrated electrode structure, the number of electrode fingers in the resonator and the reflector is illustrated to be smaller than the actual number of electrode fingers in order to facilitate understanding of the present invention. Further, in the illustrated Smith chart, the output impedance portion in the pass band of the surface acoustic wave filter is indicated by a thick line.

(Embodiment 1)
Hereinafter, Embodiment 1 will be described with reference to FIGS. 1 to 11C.

[1. Configuration of high frequency module]
First, the configuration of the high frequency module 1 according to the present embodiment will be described. FIG. 1 is a conceptual diagram showing a configuration of a high frequency module 1 according to the present embodiment.

As shown in FIG. 1, the high frequency module 1 according to the present embodiment includes a surface acoustic wave filter 10 and a low noise amplifier 20. The surface acoustic wave filter 10 has one end connected to the input terminal IN of the high frequency module 1 and the other end connected to the low noise amplifier 20. The low-noise amplifier 20 is an amplifier that amplifies a weak radio wave after reception without increasing noise as much as possible.

In the surface acoustic wave filter 10, the input impedance refers to the impedance of the surface acoustic wave filter 10 when the surface acoustic wave filter 10 is viewed from the input terminal IN side of the high frequency module 1. That is, it means the SAW input side impedance shown by the arrow in FIG. The output impedance is the impedance of the surface acoustic wave filter 10 when the surface acoustic wave filter 10 is viewed from the terminal (not shown) on the side to which the low noise amplifier 20 that is the output destination of the high frequency signal is connected. Say. That is, it means the SAW output side impedance shown by the arrow in FIG. The surface acoustic wave filter 10 connected to the low noise amplifier 20 has different input impedance and output impedance.

[2. Structure of surface acoustic wave filter]
FIG. 2A is a schematic diagram showing the configuration of the surface acoustic wave filter according to the present embodiment. FIG. 2B is a schematic diagram showing the basic configuration of the surface acoustic wave filter shown in FIG. 2A.

The surface acoustic wave filter 10 is a longitudinally coupled surface acoustic wave filter. As shown in FIG. 2A, the surface acoustic wave filter 10 includes a resonator 13, a resonator 14 and a resonator 15, a reflector 16 and a reflector 17 between an input terminal 11 and an output terminal 12. There is. The resonator 13, the resonator 14, and the resonator 15 are arranged in this order from the reflector 16 side to the reflector 17 side.

As shown in FIG. 2B, the resonator 13 has a configuration in which two IDT electrodes 130a and 130b are combined. The IDT electrode 130 a of the resonator 13 is connected to the input terminal 11. The IDT electrode 130b is connected to the ground. Similarly, the resonator 15 has a configuration in which two IDT electrodes 150a and 150b are combined. The IDT electrode 150 a of the resonator 15 is connected to the input terminal 11. The IDT electrode 150b is connected to the ground.

Further, the resonator 14 arranged between the resonator 13 and the resonator 15 has a configuration in which two IDT electrodes 140a and 140b are combined. The IDT electrode 140a of the resonator 14 is connected to the ground. The IDT electrode 140b is connected to the output terminal 12. The configuration of the resonator 14 will be described in detail later.

Further, the reflector 16 is provided with two bus bar electrodes 16a and 16b, and a plurality of electrode fingers 16c are provided between the bus bar electrodes 16a and 16b, and both ends thereof are connected to the bus bar electrodes 16a and 16b. It has and. Similarly, a plurality of reflectors 17 are provided between the two bus bar electrodes 17a and 17b and between the bus bar electrodes 17a and 17b, and electrode fingers whose both ends are connected to the bus bar electrodes 17a and 17b, respectively. 17c and.

Here, the configuration of the resonator will be described in more detail using the general resonator 100. 3A and 3B are schematic diagrams showing a configuration of a general surface acoustic wave filter, where FIG. 3A is a plan view and FIG. 3B is a cross-sectional view taken along the alternate long and short dash line shown in FIG.

As shown in FIGS. 3A and 3B, the resonator 100 is composed of a piezoelectric substrate 123 and comb-shaped IDT electrodes 101a and 101b.

The piezoelectric substrate 123 is made of, for example, a single crystal of LiNbO ₃ cut at a predetermined cut angle. In the piezoelectric substrate 123, surface acoustic waves propagate in a predetermined direction.

As shown in FIG. 3A, a pair of opposing IDT electrodes 101a and 101b are formed on the piezoelectric substrate 123. The IDT electrode 101a is composed of a plurality of electrode fingers 110a that are parallel to each other and a bus bar electrode 111a that connects the plurality of electrode fingers 110a. The IDT electrode 101b is composed of a plurality of electrode fingers 110b that are parallel to each other and a bus bar electrode 111b that connects the plurality of electrode fingers 110b. The IDT electrode 101a and the IDT electrode 101b are configured such that the plurality of electrode fingers 110b of the IDT electrode 101b are arranged between the plurality of electrode fingers 110a of the IDT electrode 101a.

Further, the IDT electrode 101a and the IDT electrode 101b have a structure in which an adhesion layer 124a and a main electrode layer 124b are laminated, as shown in FIG. 3B.

The adhesion layer 124a is a layer for improving the adhesion between the piezoelectric substrate 123 and the main electrode layer 124b, and the material thereof is, for example, NiCr.

For example, Pt is used as a material for the main electrode layer 124b. The main electrode layer 124b may have a single-layer structure composed of one layer or a laminated structure in which a plurality of layers are laminated.

The protective layer 125 is formed so as to cover the IDT electrode 101a and the IDT electrode 101b. The protective layer 125 is a layer for the purpose of protecting the main electrode layer 124b from the external environment, adjusting the frequency-temperature characteristic, and increasing the moisture resistance. The protective layer 125 is, for example, a film containing silicon dioxide as a main component. The protective layer 125 may have a single-layer structure or a laminated structure.

The materials forming the adhesion layer 124a, the main electrode layer 124b, and the protective layer 125 are not limited to the above materials. Furthermore, the IDT electrode 101a and the IDT electrode 101b do not have to have the above laminated structure. The IDT electrode 101a and the IDT electrode 101b may be made of, for example, a metal or alloy such as Ti, Al, Cu, Pt, Au, Ag, and Pd, and a plurality of layers made of the above metals or alloys. It may be configured to have a laminated laminated structure. Moreover, the protective layer 125 may not be formed.

Here, the design parameters of the IDT electrode 101a and the IDT electrode 101b will be described. Λ shown in FIG. 3B is referred to as a pitch between the electrode fingers 110a and 110b forming the IDT electrodes 101a and 101b. The main wavelength of the surface acoustic wave filter is defined by the pitch λ of the plurality of electrode fingers 110a and 110b forming the IDT electrodes 101a and 101b. The main wavelength means a wavelength in the main pitch region of the IDT electrodes 101a and 101b described later.

Specifically, the pitch λ is the length from the center of the width of one electrode finger to the center of the width of the other electrode finger of adjacent electrode fingers connected to the same bus bar electrode. For example, in FIG. 3B, from the center of the width of one electrode finger 110a connected to the bus bar electrode 111a, the same bus bar electrode 111a as the bus bar electrode 111a to which the one electrode finger 110a is connected is connected. , The length up to the center of the width of another electrode finger 110a adjacent to one electrode finger 110a.

W shown in FIG. 3B refers to the width of the electrode finger 110a of the IDT electrode 101a and the electrode finger 110b of the IDT electrode 101b in the resonator 100. Further, S shown in (b) of FIG. 3 refers to the distance between the electrode fingers 110a and 110b. Further, L shown in (a) of FIG. 3 is referred to as a cross width of the IDT electrode 101a and the IDT electrode 101b, and the length of the electrode finger where the electrode finger 110a of the IDT electrode 101a and the electrode finger 110b of the IDT electrode 101b overlap. I mean. The logarithm means the number of electrode fingers 110a or 110b.

The duty of the IDT electrodes 101a and 101b refers to the ratio of the width of the electrode fingers 110a and 110b to the repeating pitch λ of the electrode fingers 110a and 110b. More specifically, the duty of the IDT electrodes 101a and 101b is, as shown in FIG. 3B, the width of the electrode fingers 110a and 110b of the IDT electrodes 101a and 101b is W, and the electrode fingers 110a and 110b. It means W/(W+S), where S is the interval between and. The main duty means a duty in the main pitch region of the IDT electrodes 101a and 101b described later.

Further, the central portion of the resonator 100 refers to a portion within a predetermined range from the center in the propagation direction of the surface acoustic wave in the IDT electrode 101a and the IDT electrode 101b of the resonator 100. As will be described later in detail, the predetermined range is, for example, 46% of the central portion of the entire resonator 100. The predetermined range may be changed as appropriate.

The structure of the resonator 100 is not limited to the structures shown in FIGS. 3(a) and 3(b). Further, the structure of the surface acoustic wave filter 10 according to the present embodiment is not limited to the above-mentioned structure.

Hereinafter, the configuration of the resonator 14 will be described in more detail.

FIG. 4 is a schematic diagram showing details of the configuration of the surface acoustic wave filter 10a according to the present embodiment. FIG. 5 is a schematic diagram showing the structure of the resonator 14a when the number of thinning electrodes is one in the surface acoustic wave filter 10a according to the present embodiment. FIG. 6A is a schematic diagram showing the configuration of the resonator 14a when the number of thinning electrodes is two. FIG. 6B is a schematic diagram showing the configuration of the resonator 14a when the number of thinning electrodes is three.

As shown in FIG. 4, the resonator 14a has a configuration in which two IDT electrodes 140a and 140b are combined. The IDT electrode 140a has a bus bar electrode 141a and a plurality of electrode fingers 142a whose one end is connected to the bus bar electrode 141a. Similarly, the IDT electrode 140b has a bus bar electrode 141b and a plurality of electrode fingers 142b whose one end is connected to the bus bar electrode 141b. Regarding the pitch of the electrode fingers 142a and 142b, the pitch of the electrode fingers in the vicinity of both ends of the resonator 14a is narrower than the pitch of the electrode fingers in the central portion other than the vicinity of both ends. The area where the pitch of the electrode fingers is narrow is called a narrow pitch area, and the other areas are called a main pitch area. The number of pairs of electrode fingers 142a and 142b in the narrow pitch region is 3, for example.

Further, the resonator 14a has the thinning electrode 143 on the IDT electrode 140a connected to the ground. As shown in FIG. 5A, the thinning electrode 143 is a portion of the plurality of electrode fingers 142b connected to the bus bar electrode 141b of the IDT electrode 140b connected to the output terminal 12, As shown in FIG. 5B, the IDT electrode 140a connected to the ground instead of the busbar electrode 141b is connected to the busbar electrode 141a.

When one thinning electrode 143 is provided, as shown in FIG. 5B, in the IDT electrode 140a, the thinning electrode 143a is provided between the two electrode fingers 142a connected to the bus bar electrode 141a. Therefore, three electrode fingers connected to the bus bar electrode 141a are continuously arranged between the two electrode fingers 142b forming the IDT electrode 140b.

The number of thinning electrodes 143 is not limited to one and may be two or more. At this time, two or more continuous electrode fingers 142b connected to the bus bar electrode 141b may be thinning electrodes 143, or two or more non-continuous electrode fingers 142b may be thinning electrodes 143.

For example, when two continuous thinning electrodes 143a and 143b are provided, as shown in FIG. 6A, an electrode finger 142a connected to the bus bar electrode 141a is provided between the two electrode fingers 142b forming the IDT electrode 140b. Five thinning electrodes 143a and 143b are arranged in a row. Further, when three continuous thinning electrodes 143a, 143b and 143c are provided, as shown in FIG. 6B, an electrode connected to the bus bar electrode 141a is provided between the two electrode fingers 142b forming the IDT electrode 140b. Seven fingers 142a and thinning electrodes 143a, 143b, and 143c are continuously arranged. As will be described later in detail, by changing the number of thinning electrodes 143, it is possible to match the noise figure and the gain of the surface acoustic wave filter 10a and the low noise amplifier 20. That is, the number of thinned electrodes is an electrode parameter for matching the noise figure and the gain of the surface acoustic wave filter 10a and the low noise amplifier 20.

The thinning electrode 143 may be connected to the bus bar electrode 141a connected to the ground as described above, or may be connected to the bus bar electrode 141b connected to the output terminal 12.

FIG. 7 is a diagram showing the reflection characteristics on the output terminal side of the surface acoustic wave filter 10a according to the present embodiment. In FIG. 7, the reflection characteristics on the output terminal side of the surface acoustic wave filter 10a when the thinning electrodes 143 are continuously provided with 0, 1, 2, and 3 are shown by a solid line, a broken line, a dashed line, and It is indicated by a dashed line.

When the number of thinning electrodes 143 is increased to 0, 1, 2, and 3, the output impedance shifts to the capacitive side on the Smith chart, as shown in FIG. Therefore, when it is desired to change the output impedance of the surface acoustic wave filter 10a to the capacitive side, it is effective to use the thinning electrode 143. Further, by increasing the number of thinning electrodes 143 that are continuously provided, the output impedance can be changed to a more capacitive side.

Here, the position where the thinning electrode 143 is provided in the resonator 14a will be described. FIG. 8 is a schematic diagram showing the configuration of the resonator 14a for explaining the position where the thinning electrode 143a is provided in the surface acoustic wave filter 10a according to the present embodiment. FIG. 9 is a diagram showing the relationship between the position where the thinning electrode 143 is provided and the signal loss on the output terminal side of the surface acoustic wave filter 10a in the surface acoustic wave filter 10a according to the present embodiment. Note that the vertical axis of FIG. 9 indicates that the signal loss increases toward the lower side of the paper surface and the signal loss decreases toward the upper side of the paper surface.

As shown in FIG. 8, the thinned-out electrode 143 is provided in the central portion with respect to the entire resonator 14a. The region where the thinning electrode 143 is provided is called a thinning region.

In the resonator 14a, the narrow pitch region is provided near both ends in the surface acoustic wave propagation direction as described above. Here, when the position where the thinning electrode 143 is provided in the resonator 14a is changed, changing the arrangement of the electrode fingers 142a and 142b in the narrow pitch region is supposed to have some influence on the resonance mode.

For example, when thinning electrodes 143 are provided in a predetermined range on both ends of the resonator 14a in order to match the impedance on the output terminal side of the surface acoustic wave filter 10a, as shown in FIG. It can be seen that the signal loss (mismatch loss) due to the impedance mismatch on the output terminal side of the filter 10a is deteriorated, that is, increased, and the impedance matching on the output terminal side is not achieved. On the other hand, when the thinned electrode 143a is provided in the center of the resonator 14a, the mismatch loss becomes small (for example, about 5 dB), and it can be seen that the impedance on the output terminal side is matched. The mismatch loss when the thinning electrode 143 is not provided is about 5.5 dB, and when the thinning electrode 143 is provided in the central portion of the resonator 14a, that is, when the thinning region is the central portion of the resonator 14. Shows that the mismatch loss does not deteriorate as in the case where the thinning electrode 143a is not provided. More specifically, in FIG. 9, the thinning region for the mismatch loss not to deteriorate is about 46% of the central portion with respect to the entire resonator 14a.

From the above, the thinning electrode 143 is preferably provided in the central portion of the resonator 14a. For example, the thinning electrode 143 may be provided in a range of 46% of the central portion of the resonator 14a.

[3. Adjustment of output impedance of surface acoustic wave filter]
Next, as shown in FIG. 1, adjustment of the output impedance of the surface acoustic wave filter 10a when the low noise amplifier 20 is connected to the surface acoustic wave filter 10a will be described.

FIG. 10 is a diagram for explaining a method of adjusting the output impedance of the surface acoustic wave filter 10a according to the present embodiment.

Since the surface acoustic wave filter 10a is connected to the low noise amplifier 20 as shown in FIG. 1 and used as the high frequency module 1, it is necessary to adjust the output impedance so that the transmission characteristics of the high frequency module 1 as a whole are improved. is there. That is, the output impedance of the surface acoustic wave filter 10a is adjusted according to the input impedance of the low noise amplifier 20.

Specifically, in the Smith chart, the output impedance of the surface acoustic wave filter 10a is located at the complex conjugate position of the input impedance of the low noise amplifier 20 when the low noise amplifier 20 is viewed from the surface acoustic wave filter 10a side. The output impedance of the surface acoustic wave filter 10a is adjusted. Here, the input impedance of the low noise amplifier 20 is an input impedance that satisfies the characteristics improvement of both the gain and the noise figure of the low noise amplifier 20. That is, in the Smith chart, the position is located in a region between the input impedance of the low noise amplifier 20 where the gain of the low noise amplifier 20 is maximum and the input impedance of the low noise amplifier 20 where the noise figure of the low noise amplifier 20 is minimum. Is the input impedance to The output impedance of the surface acoustic wave filter 10a is adjusted to the complex conjugate region (the target Imp region at the SAW output end shown in FIG. 10) corresponding to this region.

That is, as shown in FIG. 10, in the Smith chart, the output impedance of the surface acoustic wave filter 10a when the gain of the low noise amplifier 20 becomes maximum (first impedance) in the pass band of the surface acoustic wave filter 10a. Output impedance) and the output impedance (second output impedance) of the surface acoustic wave filter 10a when the noise figure of the low-noise amplifier 20 is minimized (the target Imp region of the SAW output end). Thus, the output impedance of the surface acoustic wave filter 10a is adjusted.

At this time, the output impedance of the surface acoustic wave filter 10a is adjusted by providing the thinning electrode 143 described above. Further, the output impedance of the surface acoustic wave filter 10a is adjusted by increasing or decreasing the number of thinning electrodes 143. That is, the number of thinning electrodes 143 is used as an electrode parameter for adjusting the output impedance of the surface acoustic wave filter 10a to the target Imp region of the SAW output end. Further, in order to adjust the output impedance of the surface acoustic wave filter 10a, the electrode finger 142b of the IDT electrode 140b on the output terminal 12 side of the surface acoustic wave filter 10a may be connected to the bus bar electrode 141a to serve as the thinning electrode 143. As a result, the electrode fingers of the same polarity are lined up only in a part of the resonator 14a, so that the capacitance of the resonator 14a becomes smaller than that in the case where the thinning electrode 143 is not provided. As a result, the impedance on the output terminal side of the surface acoustic wave filter 10a, to which the resonator 14a provided with the thinning electrode 143 is connected, changes. Further, as shown in FIG. 7, by providing the thinning electrode 143, the impedance on the output terminal side of the surface acoustic wave filter 10a changes to the capacitive side, so that the SAW output end on the Smith chart is The impedance on the output terminal side of the surface acoustic wave filter 10a can be easily adjusted to the target Imp region.

FIG. 11A is a diagram showing a pass characteristic of the surface acoustic wave filter 10a when the output impedance of the surface acoustic wave filter 10a according to the present embodiment is adjusted. FIG. 11B is a diagram showing reflection characteristics on the output terminal side of the surface acoustic wave filter 10a when the output impedance of the surface acoustic wave filter 10a according to the present embodiment is adjusted. FIG. 11C is a diagram showing a pass characteristic of the high frequency module 1 when the output impedance of the surface acoustic wave filter 10a according to the present embodiment is adjusted. 11A to 11C, the characteristics when the thinning electrode 143a is not provided are shown by solid lines, and the characteristics when the thinning electrode 143 is provided are shown by broken lines.

As shown in FIG. 11A, when the output impedance of the surface acoustic wave filter 10a is adjusted, the insertion loss of the surface acoustic wave filter 10a alone is larger than that when the output impedance of the surface acoustic wave filter 10a is not adjusted. .. The output impedance in the pass band of the surface acoustic wave filter 10a at this time is adjusted to the above-mentioned target Imp region of the SAW output end, as shown in FIG. 11B.

On the other hand, regarding the pass characteristics of the entire high frequency module 1 including the low noise amplifier 20 in the surface acoustic wave filter 10a, it can be seen that the insertion loss is improved in the pass band as shown in FIG. 11C. Therefore, in the surface acoustic wave filter 10a, the thinning electrode 143 is provided in the resonator 14a on the output terminal side, and the output impedance of the surface acoustic wave filter 10a is adjusted to the target Imp region of the SAW output end described above on the Smith chart. The transmission characteristics of the entire high frequency module 1 including the low noise amplifier 20 in the surface acoustic wave filter 10a can be improved.

[4. Effect, etc.]
As described above, according to the high frequency module of the present embodiment, in the surface acoustic wave filter 10a, the thinning electrode 143 is provided on the resonator 14a on the output terminal side, and the elastic surface is provided on the target Imp region of the SAW output end described on the Smith chart. By adjusting the output impedance of the wave filter 10a, it is possible to improve the transmission characteristics of the entire high-frequency module 1 including the low-noise amplifier 20 in the surface acoustic wave filter 10a.

At this time, the output impedance of the surface acoustic wave filter 10a can be changed to be more capacitive by increasing the number of thinning electrodes 143 that are continuously provided.

(Embodiment 2)
Next, the second embodiment will be described with reference to FIGS. 12A to 14B. The high-frequency module according to the present embodiment is different from the high-frequency module 1 according to the first embodiment in that, as a method of adjusting the output impedance of the surface acoustic wave filter 10b, the IDT electrode of the resonator 14b on the output terminal side has a cross width of It is a point that is divided into two in the direction.

First, the configuration of the surface acoustic wave filter 10b according to the present embodiment will be described. FIG. 12A is a schematic diagram showing the configuration of the surface acoustic wave filter 10b according to the present embodiment. FIG. 12B is a schematic diagram showing the configuration of the resonator 14b in the surface acoustic wave filter 10b according to the present embodiment.

As shown in FIG. 12A, the surface acoustic wave filter 10b has a resonator 13, a resonator 14b, and a resonator 15. The configurations of the resonator 13 and the resonator 15 are the same as those of the resonator 13 and the resonator 15 described in the first embodiment, and thus the description thereof will be omitted.

As shown in FIG. 12A, the resonator 14b has an IDT electrode divided into two in the cross width direction. That is, as shown in FIG. 12B, the resonator 14b has the first IDT electrode 145a and the second IDT electrode 145b connected in series in the cross width direction. That is, in the surface acoustic wave filter 10b, the number of divisions of the IDT electrode is two.

Specifically, as shown in FIG. 12B, the resonator 14b has a configuration in which the IDT electrode 140a, the IDT electrode 140b, and the IDT electrode 140c are combined. The IDT electrode 140a has a bus bar electrode 141a and a plurality of electrode fingers 142a whose one end is connected to the bus bar electrode 141a, like the IDT electrode 140a described in the first embodiment. Similarly, the IDT electrode 140b has a bus bar electrode 141b and a plurality of electrode fingers 142b whose one end is connected to the bus bar electrode 141b. The IDT electrode 140c has one end connected to the bus bar electrode 141c and the bus bar electrode 141c, one end connected to the electrode finger 142c provided from the bus bar electrode 141c to the bus bar electrode 141a, and one end connected to the bus bar electrode 141c. It has electrode fingers 142d provided toward the bus bar electrode 141b. The electrode fingers 142a and 142c are arranged alternately in the propagation direction of the surface acoustic wave. Similarly, the electrode fingers 142b and 142d are alternately arranged in the surface acoustic wave propagation direction.

As a result, the first IDT electrode 145a includes the IDT electrode 140a, the bus bar electrode 141c of the IDT electrode 140c, and the electrode finger 142c. The second IDT electrode 145b includes the IDT electrode 140b, the bus bar electrode 141c of the IDT electrode 140c, and the electrode finger 142d. The bus bar electrode 141c is commonly used for the first IDT electrode 145a and the second IDT electrode 145b.

In the resonator 14b, the distance between the busbar electrode 141a and the busbar electrode 141b is the same as the distance between the busbar electrode 141a and the busbar electrode 141b in the resonator 14 in which the IDT electrodes are not divided in the cross width direction. Is. That is, the length of the first IDT electrode 145a and the second IDT electrode 145b in the cross width direction is shorter than the length of the resonator 14 in which the IDT electrode is not divided in the cross width direction. .. For example, the length of the first IDT electrode 145a and the second IDT electrode 145b in the cross width direction is about ½ of the length in the cross width direction when the IDT electrodes are not divided in the cross width direction. Has become.

With this configuration, as shown below, the output impedance of the surface acoustic wave filter 10b can be increased.

Here, the transmission characteristics of the surface acoustic wave filter 10b and the high frequency module 1 when the output impedance of the surface acoustic wave filter 10b is adjusted by the resonator 14b described above will be described.

FIG. 13 is a diagram showing reflection characteristics on the output terminal side of the surface acoustic wave filter 10b according to the present embodiment. FIG. 14A is a diagram showing a pass characteristic on the output terminal side of the surface acoustic wave filter 10b according to the present embodiment. FIG. 14B is a diagram showing noise characteristics on the output terminal side of the entire high frequency module 1 including the surface acoustic wave filter 10b according to the present embodiment. In FIG. 13, the characteristics of the surface acoustic wave filter 10 using the resonator 14 in which the IDT electrode is not divided in the cross width direction are shown by solid lines, and the surface acoustic wave filter using the resonator 14b in which the IDT electrode is divided in the cross width direction is shown. The characteristic of 10b is shown by a dashed line. 14A and 14B, the characteristics of the surface acoustic wave filter 10 using the resonator 14 in which the IDT electrode is not divided in the cross width direction are indicated by solid lines, and the elasticity using the resonator 14b in which the IDT electrode is divided in the cross width direction is used. The characteristics of the surface acoustic wave filter 10b are indicated by broken lines.

As described above, the output impedance of the surface acoustic wave filter 10b using the resonator 14b obtained by dividing the IDT electrode in the cross width direction is as shown in FIG. With respect to the output impedance of the surface acoustic wave filter 10 using No. 14, the output impedance in the pass band is increasing in the Smith chart.

This means that the first IDT electrode 145a and the second IDT electrode 145b, which are about half the length in the cross width direction, are connected in series in the cross width direction by dividing the IDT electrode into two. This is because the impedance becomes about four times as a result. Therefore, as shown in FIG. 13, in the surface acoustic wave filter 10b, the output impedance increases.

Further, as shown in FIG. 14A, when the output impedance of the surface acoustic wave filter 10b is adjusted, the insertion loss becomes larger with the surface acoustic wave filter 10b alone than when the output impedance of the surface acoustic wave filter 10b is not adjusted. ing. The output impedance in the pass band of the surface acoustic wave filter 10b at this time is adjusted to the target Imp region of the SAW output end shown in FIG. 11B in the first embodiment.

On the other hand, for the entire high frequency module 1 including the low noise amplifier 20 in the surface acoustic wave filter 10b, as shown in FIG. 14B, when the surface acoustic wave filter 10b in which the IDT electrode is divided into two is used, the IDT electrode is divided into two. It can be seen that the noise figure is reduced in the pass band of the high frequency module 1 as compared with the case where it is not. This is because the output impedance of the surface acoustic wave filter 10b is close to the NF circle of the low noise amplifier 20 on the Smith chart by configuring the surface acoustic wave filter 10b with the resonator 14b obtained by dividing the IDT electrode. It can be considered that the noise characteristics of the entire No. 1 are improved.

Therefore, in the surface acoustic wave filter 10b, the IDT electrode of the resonator 14b on the output terminal side is divided, and the output impedance of the surface acoustic wave filter 10b is adjusted to the target Imp region of the SAW output end on the Smith chart. The transmission characteristics of the entire high frequency module 1 including the low noise amplifier 20 in the surface acoustic wave filter 10b can be improved.

In the surface acoustic wave filter 10b described above, only the resonator 14b in which the IDT electrode of the resonator 14 is divided into two has been described, but the number of divisions of the IDT electrode of the resonator 14b is not limited to two, and is not limited to three. It may be more than one.

Further, in the above-described surface acoustic wave filter 10b, in order to adjust the output impedance of the surface acoustic wave filter 10b, the IDT electrode is divided for the resonator 14b connected to the output terminal of the surface acoustic wave filter 10b. When adjusting the input impedance of the surface acoustic wave filter 10b, the IDT electrode of the resonator connected to the input terminal of the surface acoustic wave filter 10 may be divided.

(Embodiment 3)
Next, a third embodiment will be described with reference to FIGS. 15 to 18B. The high frequency module according to the present embodiment is different from the high frequency module 1 according to the first embodiment in that as a method of adjusting the output impedance of the surface acoustic wave filter 10c, a resonance connected to the input terminal side of the surface acoustic wave filter 10c. This is the point where the main wavelength in the child and the main wavelength in the resonator connected to the output terminal side are adjusted.

First, a longitudinally coupled surface acoustic wave filter 10c having three resonators will be described as an example of the configuration of the surface acoustic wave filter according to the present embodiment.

FIG. 15 is a schematic diagram showing the configuration of the surface acoustic wave filter 10c according to the present embodiment. As shown in FIG. 15, the surface acoustic wave filter 10c is a longitudinally coupled surface acoustic wave filter. The surface acoustic wave filter 10 c includes a resonator 13, a resonator 14 c and a resonator 15, a reflector 16 and a reflector 17 between the input terminal 11 and the output terminal 12. The resonator 13, the resonator 14c, and the resonator 15 are arranged in this order from the reflector 16 side to the reflector 17 side.

The resonator 13 and the resonator 15 are connected to the input terminal 11 of the surface acoustic wave filter 10c. The resonator 14c is connected to the output terminal 12 of the surface acoustic wave filter 10c. The input impedance at the input terminal 11 and the output impedance at the output terminal 12 of the surface acoustic wave filter 10c are respectively 50Ω.

The configurations of the resonator 13 and the resonator 15 are similar to those of the surface acoustic wave filter 10 described in the first embodiment. The configurations of the reflector 16 and the reflector 17 are similar to those of the surface acoustic wave filter 10 described in the first embodiment.

Resonator 14c has a configuration in which two IDT electrodes 140a and 140b are combined, like resonator 14 shown in the first embodiment. The IDT electrode 140a has a bus bar electrode 141a and a plurality of electrode fingers 142a whose one end is connected to the bus bar electrode 141a. Similarly, the IDT electrode 140b has a bus bar electrode 141b and a plurality of electrode fingers 142b whose one end is connected to the bus bar electrode 141b.

The resonator 13 and the resonator 15 connected to the input terminal 11 of the surface acoustic wave filter 10c and the resonator 14c connected to the output terminal 12 of the surface acoustic wave filter 10c have different main wavelength average values. .. Regarding the resonator 14c connected to the output terminal 12, since only one resonator is connected to the output terminal 12, the main wavelength itself of the resonator 14c is the average value of the main wavelengths. The main wavelengths of the resonator 13 and the resonator 15 may be the same or different.

For example, the main wavelengths of the resonator 13 and the resonator 15 are 4.515 μm and 4.525 μm, respectively, and the average value of these main wavelengths may be 4.520 μm. The main wavelength of the resonator 14c may be 4.542 μm. Further, at this time, the average value of the main wavelengths of the resonators 14c connected to the output terminal 12 of the surface acoustic wave filter 10c, the main wavelengths of the resonators 13 and 15 connected to the input terminal 11 of the surface acoustic wave filter 10c. The ratio (main wavelength ratio) to the average value of is 1.005.

The average value of the main wavelengths of the resonator 13 and the resonator 15 connected to the input terminal 11 of the surface acoustic wave filter 10c corresponds to the first main wavelength in the present invention. Further, the average value of the main wavelengths of the resonator 14c connected to the output terminal 12 of the surface acoustic wave filter 10c corresponds to the second main wavelength in the present invention.

In this way, the resonator 13 and the resonator 15 connected to the input terminal 11 of the surface acoustic wave filter 10c are connected to the output terminal 12 of the surface acoustic wave filter 10c with respect to the average value of the main wavelengths (first main wavelength). The output impedance of the surface acoustic wave filter 10c can be adjusted as described below by changing the ratio (main wavelength ratio) of the average value (second main wavelength) of the main wavelengths of the generated resonator 14c. it can.

Hereinafter, the transmission characteristics of the surface acoustic wave filter 10c when the output impedance of the surface acoustic wave filter 10c is adjusted by changing the main wavelength ratio as described above will be described. 16A and 16B, the transmission characteristics of the surface acoustic wave filter 10c when the main wavelength ratio is 1.005, 1.008, and 1.012 in the surface acoustic wave filter 10c will be described.

FIG. 16A is a diagram showing reflection characteristics on the output terminal side of the surface acoustic wave filter 10c according to the present embodiment. FIG. 16B is a diagram showing a pass characteristic on the output terminal side of the surface acoustic wave filter 10c according to the present embodiment. In FIGS. 16A and 16B, the characteristics of the surface acoustic wave filter 10c when the main wavelength ratio is 1.005, 1.008, and 1.012 are indicated by a solid line, a dashed-dotted line, and a broken line, respectively.

As shown in FIG. 16A, the output impedance in the pass band of the surface acoustic wave filter 10c when the main wavelength ratio is 1.005, 1.008, and 1.012 is right on the Smith chart as the main wavelength ratio increases. Is moving in the direction. That is, it can be seen that the output impedance of the surface acoustic wave filter 10c increases as the main wavelength ratio increases.

Therefore, in the surface acoustic wave filter 10c, by increasing the main wavelength ratio of the resonators 13, 14c and 15, the output impedance of the surface acoustic wave filter 10c can be increased to more than 50Ω.

When the low noise amplifier 20 is provided after the surface acoustic wave filter 10c as in the high frequency module 1 shown in FIG. 1, the output impedance of the surface acoustic wave filter 10c is preferably about 70Ω. In order to increase the output impedance of the surface acoustic wave filter 10c to about 70Ω, the main wavelength ratio is preferably 1.01 or more.

Further, as shown in FIG. 16B, when the main wavelength ratio is 1.005, 1.008, and 1.012, the pass band width of the surface acoustic wave filter 10c is expanded. That is, as the main wavelength ratio is increased, the pass band of the surface acoustic wave filter 10c is expanded.

Further, FIG. 17 is a schematic diagram showing a configuration of a longitudinally coupled surface acoustic wave filter 10d having five resonators as another configuration of the surface acoustic wave filter according to the present embodiment.

As shown in FIG. 17, the surface acoustic wave filter 10 d includes a resonator 23 a, a resonator 24 a, a resonator 25 a, a resonator 26 a and a resonator 27 a, and a reflector 16 between the input terminal 11 and the output terminal 12. And a reflector 17. The resonator 23a, the resonator 24a, the resonator 25a, the resonator 26a, and the resonator 27a are arranged in this order from the reflector 16 side to the reflector 17 side.

The resonator 23a, the resonator 25a, and the resonator 27a are connected to the input terminal 11 of the surface acoustic wave filter 10d. The resonator 24a and the resonator 26a are connected to the output terminal 12 of the surface acoustic wave filter 10d. The input impedance at the input terminal 11 and the output impedance at the output terminal 12 of the surface acoustic wave filter 10d are each 50Ω.

The configurations of the resonator 23a, the resonator 25a, and the resonator 27a are similar to those of the resonator 13 of the surface acoustic wave filter 10c described above. The configurations of the resonator 24a and the resonator 26a are similar to those of the resonator 14 of the surface acoustic wave filter 10c described above.

The resonator 23a, the resonator 25a and the resonator 27a connected to the input terminal 11 of the surface acoustic wave filter 10d and the resonator 24a and the resonator 26a connected to the output terminal 12 of the surface acoustic wave filter 10d are the main components. The wavelength averages are different. The main wavelengths of the resonator 23a, the resonator 25a, and the resonator 27a may be the same or different. Further, the main wavelengths of the resonator 24a and the resonator 26a may be the same or different.

The average value of the main wavelengths of the resonator 23a, the resonator 25a, and the resonator 27a connected to the input terminal 11 of the surface acoustic wave filter 10d corresponds to the first main wavelength in the present invention. Further, the average value of the main wavelengths of the resonator 24a and the resonator 26a connected to the output terminal 12 of the surface acoustic wave filter 10d corresponds to the second main wavelength in the present invention.

Connected to the output terminal 12 of the surface acoustic wave filter 10d for the average value (first main wavelength) of the main wavelengths of the resonator 23a, the resonator 25a, and the resonator 27a connected to the input terminal 11 of the surface acoustic wave filter 10d. By changing the ratio (main wavelength ratio) of the average values (second main wavelengths) of the main wavelengths of the resonators 24a and 26a that have been generated, as described below, the surface acoustic wave filter 10d The output impedance can be adjusted.

Hereinafter, the transmission characteristics of the surface acoustic wave filter 10d when the output impedance of the surface acoustic wave filter 10d is adjusted by changing the main wavelength ratio as described above will be described. 18A and 18B, the transmission characteristics of the surface acoustic wave filter 10d when the main wavelength ratio is 1.005, 1.008, and 1.012 in the surface acoustic wave filter 10d will be described.

FIG. 18A is a diagram showing reflection characteristics on the output terminal side of the surface acoustic wave filter 10d according to the present embodiment. FIG. 18B is a diagram showing pass characteristics on the output terminal side of the surface acoustic wave filter 10d according to the present embodiment. 18A and 18B, the characteristics of the surface acoustic wave filter 10d when the main wavelength ratio is set to 1.005, 1.008, and 1.012 are shown by a solid line, a dashed-dotted line, and a broken line, respectively.

The output impedance in the pass band of the surface acoustic wave filter 10d when the main wavelength ratio is 1.005, 1.008, and 1.012 is the same as that of the surface acoustic wave filter 10c described above, as shown in FIG. 18A. , As the main wavelength ratio becomes larger, it moves to the right on the Smith chart. That is, it can be seen that the output impedance of the surface acoustic wave filter 10d increases as the main wavelength ratio increases.

Therefore, in the surface acoustic wave filter 10d, by increasing the main wavelength ratio of the resonator 23a, the resonator 24a, the resonator 25a, the resonator 26a, and the resonator 27a, the output impedance of the surface acoustic wave filter 10d is more than 50Ω. Can be increased.

Further, comparing FIG. 18A and FIG. 16A, the output impedance of the surface acoustic wave filter 10d having five resonators is larger than that of the surface acoustic wave filter 10c having three resonators. It can be seen that the output impedance winding in the pass band of the filter 10d is small. That is, by increasing the number of resonators as in the surface acoustic wave filter 10d, the output impedance of the surface acoustic wave filter 10d can be increased and stabilized.

In the surface acoustic wave filter 10d as well, in order to increase the output impedance to about 70Ω, the main wavelength ratio is preferably set to 1.01 or more.

Further, as shown in FIG. 18B, when the main wavelength ratio is 1.005, 1.008, and 1.012, the pass band width of the surface acoustic wave filter 10d is expanded similarly to the surface acoustic wave filter 10c described above. doing. That is, it can be seen that the pass band of the surface acoustic wave filter 10d expands as the main wavelength ratio increases.

In addition, although this Embodiment demonstrated the surface acoustic wave filter 10c which has three resonators, and the surface acoustic wave filter 10d which has five resonators, the number of resonators is not limited to these. , May be changed.

(Embodiment 4)
Next, a fourth embodiment will be described with reference to FIGS. 19 to 22B. The high-frequency module according to the present embodiment is different from the high-frequency module 1 according to the first embodiment in that as a method of adjusting the output impedance of the surface acoustic wave filter 10, a resonance connected to the output terminal side of the surface acoustic wave filter 10 is used. This is the point that the main duty of the child is adjusted.

First, a longitudinally coupled surface acoustic wave filter 10e having three resonators will be described as an example of the configuration of the surface acoustic wave filter according to the present embodiment.

FIG. 19 is a schematic diagram showing the configuration of the surface acoustic wave filter 10e according to the present embodiment.

As shown in FIG. 19, the surface acoustic wave filter 10e is a longitudinally coupled surface acoustic wave filter. Similar to the surface acoustic wave filter 10c shown in the third embodiment, the surface acoustic wave filter 10e includes a resonator 13, a resonator 14d, a resonator 15 and a reflector 16 between the input terminal 11 and the output terminal 12. And a reflector 17. The resonator 13, the resonator 14d, and the resonator 15 are arranged in this order from the reflector 16 side to the reflector 17 side.

The resonator 13 and the resonator 15 are connected to the input terminal 11 of the surface acoustic wave filter 10e. The resonator 14d is connected to the output terminal 12 of the surface acoustic wave filter 10e. The configurations of the resonator 13 and the resonator 15 are similar to those of the surface acoustic wave filter 10 described in the first embodiment. The resonator 14d is the same as the resonator 14 shown in the first embodiment except for the main duty.

The main duty of the resonator 14d is, for example, 0.64. By changing the main duty of the resonator 14d connected to the output terminal 12 of the surface acoustic wave filter 10e, the output impedance of the surface acoustic wave filter 10e can be adjusted as described below.

Hereinafter, the transmission characteristics of the surface acoustic wave filter 10e when the output impedance of the surface acoustic wave filter 10e is adjusted by changing the main duty as described above will be described. 20A and 20B, the transmission characteristics of the surface acoustic wave filter 10e when the main duties of the surface acoustic wave filter 10e are 0.64, 0.71 and 0.75 will be described.

FIG. 20A is a diagram showing reflection characteristics on the output terminal side of the surface acoustic wave filter 10e according to the present embodiment. FIG. 20B is a diagram showing pass characteristics on the output terminal side of the surface acoustic wave filter 10e according to the present embodiment. 20A and 20B, the characteristics of the surface acoustic wave filter 10e when the main duty of the resonator 14d is set to 0.64, 0.71 and 0.75 are indicated by a one-dot chain line, a solid line and a broken line, respectively.

As shown in FIG. 20A, the output impedance in the pass band of the surface acoustic wave filter 10e when the main duty of the resonator 14d is 0.64, 0.71, and 0.75 is Smith chart as the main duty increases. Is moving to the left. That is, as the main duty is increased, the output impedance of the surface acoustic wave filter 10e decreases.

Therefore, in the surface acoustic wave filter 10e, the output impedance of the surface acoustic wave filter 10e can be increased more than 50Ω by reducing the main duty of the resonator 14d.

When the low noise amplifier 20 is provided after the surface acoustic wave filter 10e as in the high frequency module 1 shown in FIG. 1, the output impedance of the surface acoustic wave filter 10e is preferably about 70Ω. In order to increase the output impedance of the surface acoustic wave filter 10e to approximately 70Ω, it is desirable that the main duty of the resonator 14d be larger than 0.55 and smaller than 0.75. When the output impedance of the surface acoustic wave filter 10e is 50Ω, the main duty of the resonator 14d is a value larger than 0.4 and smaller than 0.6, for example.

As shown in FIG. 20B, even if the main duty is changed to 0.64, 0.71 and 0.75, the pass band width of the surface acoustic wave filter 10e hardly changes. That is, by changing the main duty, the output impedance of the surface acoustic wave filter 10e can be changed without changing the pass band of the surface acoustic wave filter 10e.

FIG. 21 is a schematic diagram showing a configuration of a longitudinally coupled surface acoustic wave filter 10f having five resonators as another configuration of the surface acoustic wave filter according to the present embodiment.

As shown in FIG. 21, the surface acoustic wave filter 10f includes a resonator 23b, a resonator 24b, a resonator 25b, a resonator 26b and a resonator 27b, and a reflector 16 between the input terminal 11 and the output terminal 12. And a reflector 17. The resonator 23b, the resonator 24b, the resonator 25b, the resonator 26b, and the resonator 27b are arranged in this order from the reflector 16 side to the reflector 17 side.

The resonator 24b and the resonator 26b are connected to the input terminal 11 of the surface acoustic wave filter 10f. The resonator 23b, the resonator 25b, and the resonator 27b are connected to the output terminal 12 of the surface acoustic wave filter 10f. The input impedance at the input terminal 11 and the output impedance at the output terminal 12 of the surface acoustic wave filter 10f are respectively 50Ω.

The configurations of the resonator 24b and the resonator 26b are similar to those of the resonator 13 of the surface acoustic wave filter 10e described above. The configurations of the resonator 23b, the resonator 25b, and the resonator 27b are the same as the resonator 14d of the surface acoustic wave filter 10e described above.

Here, the transmission characteristics of the surface acoustic wave filter 10f when the output impedance of the surface acoustic wave filter 10f is adjusted by changing the main duty as described above will be described. 22A and 22B, the transmission characteristics of the surface acoustic wave filter 10f when the main duty of the surface acoustic wave filter 10f is small, medium, and large will be described. In the surface acoustic wave filter 10f, the main duty is small when the main duty of the resonators 23b and 27b is 0.64 and the main duty of the resonator 25b is 0.67. Further, in the surface acoustic wave filter 10f, the main duty is medium when the main duty of the resonators 23b and 27b is 0.70 and the main duty of the resonator 25b is 0.74. In the surface acoustic wave filter 10f, the main duty is large when the main duties of the resonators 23b and 27b are 0.74 and the main duty of the resonator 25b is 0.77.

FIG. 22A is a diagram showing reflection characteristics on the output terminal side of the surface acoustic wave filter 10f according to the present embodiment. FIG. 22B is a diagram showing pass characteristics on the output terminal side of the surface acoustic wave filter 10f according to the present embodiment. 22A and 22B, the characteristics of the surface acoustic wave filter 10f when the main duty is set to the above-described small, medium, and large are shown by a solid line, a one-dot chain line, and a broken line, respectively.

The output impedance in the pass band of the surface acoustic wave filter 10f is the same as that of the surface acoustic wave filter 10e when the main duty of the resonators 23b, 25b, and 27b connected to the output terminal 12 is set to the above-mentioned small, medium, and large. 22A, as the main duty of the resonators 23b, 25b, and 27b increases, the resonators move to the left in the Smith chart. That is, as the main duty of the resonators 23b, 25b and 27b is increased, the output impedance of the surface acoustic wave filter 10f decreases.

Therefore, in the surface acoustic wave filter 10f, by reducing the main duty of the resonators 23b, 25b and 27b, the output impedance of the surface acoustic wave filter 10f can be increased to more than 50Ω.

When the low noise amplifier 20 is provided after the surface acoustic wave filter 10f like the high frequency module 1 shown in FIG. 1, the output impedance of the surface acoustic wave filter 10f is preferably about 70Ω. In order to increase the output impedance of the surface acoustic wave filter 10f to about 70Ω, it is desirable that the main duty of each of the resonators 23b, 25b and 27b be larger than 0.55 and smaller than 0.75.

As shown in FIG. 22B, even if the main duty of the resonators 23b, 25b, and 27b is changed to the above-mentioned small, medium, and large, the pass band width of the surface acoustic wave filter 10f hardly changes. That is, by changing the main duty of the resonators 23b, 25b and 27b, the output impedance of the surface acoustic wave filter 10f can be changed without changing the pass band of the surface acoustic wave filter 10f.

The value of the main duty is not limited to the value described above, and may be changed as appropriate.

(Embodiment 5)
Next, a fifth embodiment will be described with reference to FIGS. 23 to 25B. The high-frequency module according to the present embodiment is different from the high-frequency module 1 according to the first embodiment in that in the surface acoustic wave filter 10g, the wiring between the resonator connected to the output terminal and the output terminal is the wiring concerned. The point is that the interlayer insulating film 40 is disposed between the substrate and the substrate.

FIG. 23 is a schematic diagram showing the configuration of the surface acoustic wave filter 10g according to the present embodiment. As shown in FIG. 23, a surface acoustic wave filter 10g according to the present embodiment has a configuration in which two longitudinally coupled surface acoustic wave resonators 10ga and 10gb are connected in series.

As shown in FIG. 23, the first surface acoustic wave resonator 10ga includes a resonator 33a, a resonator 34a and a resonator 35a, and a reflector 36a and a reflector 37a. The resonator 33a, the resonator 34a, and the resonator 35a are arranged in this order from the reflector 36a side to the reflector 37a side. The resonator 33a, the resonator 34a and the resonator 35a, and the reflector 36a and the reflector 37a are configured as follows: the resonator 13, the resonator 14 and the resonator 15 of the surface acoustic wave filter 10 described in the first embodiment. The configurations of the reflector 16 and the reflector 17 are similar.

Similarly, the second surface acoustic wave resonator 10gb includes a resonator 33b, a resonator 34b and a resonator 35b, and a reflector 36b and a reflector 37b, as shown in FIG. The resonator 33b, the resonator 34b, and the resonator 35b are arranged in this order from the reflector 36b side to the reflector 37b side. The resonator 33b, the resonator 34b and the resonator 35b, and the reflector 36b and the reflector 37b are composed of the resonator 13, the resonator 14 and the resonator 15 of the surface acoustic wave filter 10 shown in the first embodiment. The configurations of the reflector 16 and the reflector 17 are similar.

In the resonator 34a, one of the pair of IDT electrodes is connected to the input terminal 11 of the surface acoustic wave filter 10g. In the resonator 34b, one of the pair of IDT electrodes is connected to the output terminal 12 of the surface acoustic wave filter 10g. The other of the pair of IDT electrodes of the resonator 34a and the other of the pair of IDT electrodes of the resonator 34b are connected to the ground.

In the resonator 33a, one of the pair of IDT electrodes is connected to one of the pair of IDT electrodes of the resonator 33b. The other of the pair of IDT electrodes of the resonator 33a and the other of the pair of IDT electrodes of the resonator 33b are connected to the ground.

Similarly, in the resonator 35a, one of the pair of IDT electrodes is connected to one of the pair of IDT electrodes of the resonator 35b. The other of the pair of IDT electrodes of the resonator 35a and the other of the pair of IDT electrodes of the resonator 35b are connected to the ground.

With this configuration, in the surface acoustic wave filter 10g, the longitudinally coupled first surface acoustic wave resonator 10ga and the second surface acoustic wave resonator 10gb are directly connected between the input terminal 11 and the output terminal 12. It is a connected configuration. In this way, when the surface acoustic wave filter 10g is composed of a plurality of stages of surface acoustic wave resonators, in order to secure the ground of each surface acoustic wave resonator, three-dimensional wiring is performed using an interlayer insulating film. May be done. That is, an interlayer insulating film may be provided on one lead wiring and another lead wiring may be formed on the interlayer insulating film.

In the surface acoustic wave filter 10g according to the present embodiment, one IDT electrode of the resonator 34b and the output terminal 12 that do not require wiring in a three-dimensional manner are provided at positions not requiring such three-dimensional wiring. An interlayer insulating film 40 is provided between the wiring 39 and the piezoelectric substrate 42 at the position of the wiring 39 to be connected.

FIG. 24A is a cross-sectional view showing the configuration of the surface acoustic wave filter 10g shown in FIG. 23 taken along the line BB. 24B is a cross-sectional view showing the configuration of the surface acoustic wave filter 10g shown in FIG. 23 taken along the line CC.

As shown in FIGS. 24A and 24B, surface acoustic wave filter 10g is formed on piezoelectric substrate 42, similar to surface acoustic wave filter 10 shown in the first embodiment. The wiring connected to the IDT electrode of the resonator has the same structure as the IDT electrode.

Specifically, as shown in FIG. 24A, the wiring 38 that connects one IDT electrode of the resonator 34b to the ground in FIG. 23 includes the first electrode layer 38a formed on the piezoelectric substrate 42 and the first electrode layer 38a. And the second electrode layer 38b formed on the electrode layer 38a.

The first electrode layer 38a is formed integrally with the main electrode layer of the IDT electrode, and is made of, for example, Pt, Cu, Au, Ag, Ta, W or the like. The first electrode layer 38a may include an adhesion layer (see FIG. 3B) on the piezoelectric substrate 42 side. The thickness of the first electrode layer 38a is on the order of submicrons, and is, for example, 0.2 μm. The second electrode layer 38b is composed of, for example, Pt, Cu, Au, Ag, Ta, W, or the like. The thickness of the second electrode layer 38b is on the order of microns, and is, for example, 2 μm.

Further, a protective layer 44 is formed so as to cover the second electrode layer 38b. The protective layer 44 is made of, for example, SiO ₂ . The protective layer 44 has a thickness of several tens of nm, for example, 30 nm.

23, the wiring 39 connecting the other IDT electrode of the resonator 34b and the output terminal 12 is formed on the interlayer insulating film 40 formed on the piezoelectric substrate 42, as shown in FIG. 24B. .. That is, as compared with the wiring 38 described above, in the wiring 39, the interlayer insulating film 40 is formed instead of the first electrode layer 38a.

The interlayer insulating film 40 is made of, for example, polyimide. The thickness of the interlayer insulating film is on the order of microns, and is, for example, 3 μm. The wiring 39 is made of the same material as the second electrode layer 38b shown in FIG. 24A. The wiring 39 is composed of, for example, Pt, Cu, Au, Ag, Ta, W, or the like. As shown in FIG. 24B, a protective layer 44 is formed on the piezoelectric substrate 42 so as to cover the interlayer insulating film 40 and the wiring 39.

By providing the interlayer insulating film 40 between the wiring 39 connected to the output terminal 12 and the piezoelectric substrate 42, the piezoelectric substrate 42 and the wiring 39 are separated from each other as compared with the configuration of the wiring 38 in which the interlayer insulating film 40 is not provided. Capacitive coupling between them can be reduced. As a result, the output impedance of the surface acoustic wave filter 10g can be adjusted to be inductive.

Further, as shown in FIG. 24B, by making the area of the interlayer insulating film 40 larger than the area of the wiring 39, it is possible to further reduce the capacitive coupling between the piezoelectric substrate 42 and the wiring 39. As a result, the output impedance of the surface acoustic wave filter 10g can be adjusted to be more inductive.

The transmission characteristics of the surface acoustic wave filter 10g with and without the interlayer insulating film 40 will be described below.

FIG. 25A is a diagram showing reflection characteristics on the output terminal side of a surface acoustic wave filter 10g having another configuration according to the present embodiment. FIG. 25B is a diagram showing noise characteristics after the low noise amplifier 20 is connected to the surface acoustic wave filter 10g according to the present embodiment. 25A and 25B, the characteristics of the surface acoustic wave filter 10g in the case where the interlayer insulating film 40 is not provided between the wiring 39 connected to the output terminal 12 and the piezoelectric substrate 42 are indicated by the solid line and the first electrode layer 38a. The characteristic of the surface acoustic wave filter 10g in the case where the interlayer insulating film 40 is provided instead of the above is shown by a broken line.

The output impedance in the pass band of the surface acoustic wave filter 10g when the interlayer insulating film 40 is provided instead of the first electrode layer 38a is, as shown in FIG. 25A, the elastic surface when the interlayer insulating film 40 is not provided. It can be seen that, as compared with the output impedance in the pass band of the wave filter 10g, it moves to the upper right on the Smith chart, that is, to the inductive side. Therefore, by providing the interlayer insulating film 40, the capacitive coupling between the piezoelectric substrate 42 and the wiring 39 can be reduced.

Further, in the high frequency module 1 in which the low noise amplifier 20 is connected to the output side of the surface acoustic wave filter 10g, the interlayer insulating film 40 is provided between the wiring 39 and the piezoelectric substrate 42 as shown in FIG. 25B. It can be seen that the noise figure is reduced compared to the case where the interlayer insulating film 40 is not provided. Therefore, by providing the interlayer insulating film 40 between the wiring 39 and the piezoelectric substrate 42 in the surface acoustic wave filter 10g, it is possible to improve noise characteristics in the entire high frequency module 1.

In the surface acoustic wave filter 10g described above, the wiring 39 connected to the output terminal 12 is different from the wiring 38 in that the interlayer insulating film 40 is formed instead of the first electrode layer 38a. The wiring 39 may have a structure including both the first electrode layer and the second electrode layer.

FIG. 26 is a cross-sectional view showing another configuration of the surface acoustic wave filter 10g shown in FIG. 23 taken along the line CC. The wiring 39 shown in FIG. 26 has a first electrode layer 39a and a second electrode layer 39b, like the wiring 38 shown in FIG. 24A. The configurations of the first electrode layer 39a and the second electrode layer 39b are similar to those of the first electrode layer 38a and the second electrode layer 38b. An interlayer insulating film 40 is formed between the wiring 39 and the piezoelectric substrate 42. A protective layer 44 is formed on the piezoelectric substrate 42 so as to cover the interlayer insulating film 40 and the wiring 39.

When the interlayer insulating film 40 is provided between the wiring 39 and the piezoelectric substrate 42, it is better to provide the interlayer insulating film 40 instead of the first electrode layer 39a so that the interlayer insulating film 40 is left with the first electrode layer 39a left. The change in the output impedance of the surface acoustic wave filter 10g is larger than that in the case where the surface acoustic wave filter 10g is provided. Therefore, when it is desired to greatly adjust the change in the output impedance of the surface acoustic wave filter 10g, the interlayer insulating film 40 is provided in place of the first electrode layer 39a, and the change in the output impedance of the surface acoustic wave filter 10g is adjusted to be small. In that case, it is preferable to provide the interlayer insulating film 40 while leaving the first electrode layer 39a.

Although the surface acoustic wave filter 10g according to the present embodiment is configured to include the first surface acoustic wave resonator 10ga and the second surface acoustic wave resonator 10gb, the present invention is not limited to this. The filter 10g may be composed of a single-stage longitudinally coupled surface acoustic wave resonator, or may be composed of a multi-staged longitudinally coupled surface acoustic wave resonator.

(Other embodiments)
It should be noted that the present invention is not limited to the configurations described in the above-described embodiments, and may be appropriately modified, for example, as in the modified examples described below.

For example, in the above-described embodiment, as electrode parameters for adjusting the output impedance of the surface acoustic wave filter, the number of thinned electrodes of the resonator connected to the output terminal, the number of divisions of the resonator in the cross width direction, and the resonance Although the main wavelength and the main duty of the child have been described, other parameters may be used as the electrode parameters. For example, the pitch of the electrode fingers of the resonator, the number of pairs of electrode fingers, or the like may be used as the electrode parameter. Further, the value of the electrode parameter is not limited to the value shown in the above-mentioned embodiment, and may be changed appropriately.

Further, the number of resonators forming the surface acoustic wave filter is not limited to three or five, and may be changed.

The materials of the substrate, the electrodes, the protective layer, and the like that form the resonator are not limited to those described above, and may be appropriately changed. Further, the size, pitch and logarithm of the electrode fingers of each resonator may be changed as long as the above-mentioned conditions are satisfied.

Further, in the above-described embodiment, the surface acoustic wave filter and the low noise amplifier are directly connected, but a matching element may be further provided between the surface acoustic wave filter and the low noise amplifier. According to the surface acoustic wave filter of the present embodiment, since the output impedance of the surface acoustic wave filter can be adjusted, the surface acoustic wave filter and the low noise amplifier are directly connected as described above without providing a matching element. Even if they are directly connected, it is possible to achieve low loss and low noise.

Other forms obtained by making various modifications to those skilled in the art to the above-described embodiments and modifications, or components and functions in the above-described embodiments and modifications without departing from the spirit of the present invention The present invention also includes a form realized by arbitrarily combining.

INDUSTRIAL APPLICABILITY The present invention can be used for a high frequency module, a duplexer, a multiplexer, a receiving device, etc. using a surface acoustic wave filter connected to a low noise amplifier.

1 high-frequency module 10, 10a, 10b, 10c, 10d, 10e, 10f, 10g surface acoustic wave filter 10ga first surface acoustic wave resonator 10gb second surface acoustic wave resonator 11 input terminal 12 output terminal 13, 14, 14a, 14b, 14c, 14d, 15, 23a, 23b, 24a, 24b, 25a, 25b, 26a, 26b, 27a, 27b, 33a, 33b, 34a, 34b, 35a, 35b, 100 resonators 16, 17, 36a , 36b, 37a, 37b Reflectors 16a, 16b, 17a, 17b, 111a, 111b, 141a, 141b, 141c Busbar electrodes 16c, 17c, 110a, 110b, 142a, 142b, 142c, 142d Electrode fingers 38, 39 Wiring 38a, 39a 1st electrode layer 38b, 39b 2nd electrode layer 40 Interlayer insulation film 42,123 Piezoelectric substrate 44,125 Protective layer 101a, 101b, 130a, 130b, 140a, 140b, 140c, 150a, 150b IDT electrode 143, 143a , 143b, 143c Thinning electrode 124a Adhesion layer 124b Main electrode layer 145a First IDT electrode 145b Second IDT electrode

Claims (10)

A longitudinally coupled surface acoustic wave filter including a plurality of resonators,
A low noise amplifier that is connected to the surface acoustic wave filter and amplifies a high frequency signal that has passed through the surface acoustic wave filter,
The input impedance and the output impedance of the surface acoustic wave filter connected to the low noise amplifier are different,
In the Smith chart, the output impedance in the pass band of the surface acoustic wave filter is located at a complex conjugate position with the input impedance of the low noise amplifier that satisfies both the gain and the noise figure of the low noise amplifier ,
The wiring between the IDT electrode of the resonator connected to the output terminal of the surface acoustic wave filter and the output terminal of the surface acoustic wave filter is formed on the interlayer insulating film formed on the piezoelectric substrate. ing,
High frequency module. An IDT (Inter Digital Transducer) electrode of at least one of the resonators connected to an output terminal of the surface acoustic wave filter has a thinning electrode,
In the Smith chart, the output impedance in the pass band of the surface acoustic wave filter, the electrode parameter for the position of the complex conjugate with the input impedance of the low noise amplifier is the number of the thinned electrodes,
The high frequency module according to claim 1. The thinning electrode is provided in the central portion of the resonator,
The high frequency module according to claim 2. The thinning electrode is provided in a range of 46% of a central portion of the resonator,
The high frequency module according to claim 3. The IDT electrode of the resonator connected to the output terminal of the surface acoustic wave filter is divided in the cross width direction,
In the Smith chart, the electrode parameter for the output impedance in the pass band of the surface acoustic wave filter to be in a complex conjugate position with the input impedance of the low noise amplifier is the number of divisions of the IDT electrode in the cross width direction. is there,
The high frequency module according to claim 1. In the Smith chart, the electrode parameter for the output impedance in the pass band of the surface acoustic wave filter being in the position of complex conjugate with the input impedance of the low noise amplifier is connected to the input terminal of the surface acoustic wave filter. A first main wavelength, which is an average value of main wavelengths in the resonator, and a second main wavelength, which is an average value of main wavelengths in the resonator connected to the output terminal of the surface acoustic wave filter,
The first main wavelength and the second main wavelength are different,
The high frequency module according to claim 1. The electrode parameter is a resonator connected to an output terminal of the surface acoustic wave filter for a first main wavelength that is an average value of main wavelengths of the resonator connected to an input terminal of the surface acoustic wave filter. The main wavelength ratio which is the ratio of the second main wavelength which is the average value of the main wavelengths in
The main wavelength ratio is 1.01 or more,
The high frequency module according to claim 6. In the Smith chart, the electrode parameter for the output impedance in the pass band of the surface acoustic wave filter being in the position of complex conjugate with the input impedance of the low noise amplifier is connected to the output terminal of the surface acoustic wave filter. Is the main duty in the resonator,
The main duty is greater than 0.55 and less than 0.75,
The high frequency module according to claim 1. The IDT electrode of the resonator connected to the output terminal of the surface acoustic wave filter has a first electrode layer formed on the piezoelectric substrate and a second electrode layer formed on the first electrode layer. And an electrode layer,
The wiring at the position where the interlayer insulating film is arranged is composed of the first electrode layer and the second electrode layer,
The high frequency module according to claim 1. The IDT electrode of the resonator connected to the output terminal of the surface acoustic wave filter has a first electrode layer formed on a substrate and a second electrode formed on the first electrode layer. With layers,
The wiring at the position where the interlayer insulating film is arranged is composed of a second electrode layer formed on the interlayer insulating film,
The high frequency module according to claim 1.

Images