Elastic wave device and module with the same

Abstract

To provide a small elastic wave device in which harmonic components of amplification signals are reduced.SOLUTION: The elastic wave device includes: a package substrate having a first inductor, a second inductor, an antenna terminal, a transmission terminal, and a reception terminal; a piezoelectric substrate on the package substrate; a plurality of serial resonators and a plurality of parallel resonators on the piezoelectric substrate, the serial resonators and the parallel resonators forming a ladder filter; an antenna pad, a transmission pad, a reception pad, and a ground pad on the piezoelectric substrate; and a notch resonator on the piezoelectric substrate, the notch resonator having a resonant frequency higher than the frequency band of the ladder-type filter, the first inductor being connected to the antenna pad, the second inductor being connected to the antenna terminal, and the notch resonator being connected to one of the parallel resonators and a node between the first inductor and the second inductor.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present disclosure relates to an elastic wave device and a module including the elastic wave device.

Background Art

[0002] Patent Document 1 discloses a matching circuit. The matching circuit performs output impedance matching of an amplifier that amplifies an input signal and outputs an amplified signal. The matching circuit includes a low-pass filter and a high-pass filter. The ground of the low-pass filter and the ground of the high-pass filter are separated. Thereby, interference between the low-pass filter and the high-pass filter is suppressed. Therefore, the harmonic component of the amplified signal can be attenuated.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in Patent Document 1, in order to attenuate the harmonic component of the amplified signal, a new matching circuit is required. Therefore, when the matching circuit is applied to an elastic wave device, the elastic wave device becomes large.

[0005] The present disclosure has been made to solve the above problems. An object of the present disclosure is to provide an elastic wave device capable of reducing the harmonic component of an amplified signal while achieving miniaturization, and a module including the elastic wave device.

Means for Solving the Problems

[0006] The elastic wave device according to the present disclosure is A package substrate including a first inductor, a second inductor, an antenna terminal, a transmission terminal, and a reception terminal, a chip substrate mounted on the package substrate, a plurality of series resonators and a plurality of parallel resonators formed on the chip substrate and constituting a ladder-type filter, an antenna pad, a transmission pad, a reception pad, and a ground pad formed on the chip substrate, a notch resonator formed on the chip substrate and having a resonance frequency higher than the frequency band of the ladder-type filter, and comprising: The first inductor is connected to the antenna pad, The second inductor is connected to the antenna terminal, The notch resonator is connected to a node between any one of the plurality of parallel resonators, the first inductor, and the second inductor.

[0007] A notch pad formed on the chip substrate and to which only the notch resonator is connected, is one aspect of the present disclosure.

[0008] A capacitor formed on the chip substrate, connected between the antenna pad and the series resonator closest to the antenna pad among the plurality of series resonators, and connected to a node between the second inductor and the antenna terminal, is one aspect of the present disclosure.

[0009] The surface acoustic wave device, an amplifier for amplifying a signal input to the transmission terminal, A module including the above is one aspect of the present disclosure.

Advantages of the Invention

[0010] According to the present disclosure, it is possible to reduce the size of an elastic wave device or the like while attenuating the harmonic components of the amplified signal.

Brief Description of the Drawings

[0011]

Figure 1

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Figure 8

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Figure 10

Embodiments for Carrying Out the Invention

[0012] The embodiments will be described with reference to the accompanying drawings. In each figure, the same or corresponding parts are denoted by the same reference numerals. The redundant description of such parts will be appropriately simplified or omitted.

[0013] Embodiment 1. FIG. 1 is a cross-sectional view of the elastic wave device in Embodiment 1.

[0014] As shown in FIG. 1, the elastic wave device 1 includes a package substrate 2, a chip substrate 3, a plurality of bumps 4, and a sealing portion 5.

[0015] For example, the package substrate 2 is a multilayer substrate containing resin. For example, the package substrate 2 is a low temperature co-fired ceramics (LTCC) multilayer substrate composed of a plurality of dielectric layers. For example, the package substrate 2 incorporates passive elements such as capacitors or inductors (for example, inductor element L).

[0016] In FIG. 1, the upper surface of the package substrate 2 is a component mounting surface. A plurality of conductive pads 2A are formed on the upper surface of the package substrate 2. For example, the plurality of conductive pads 2A are formed of copper. The lower surface of the package substrate 2 is a mounting surface to a mother board or the like. A plurality of conductive pads 2B are formed on the lower surface of the package substrate 2. For example, the plurality of conductive pads 2B are formed of copper. A plurality of internal conductors 2C are incorporated in the package substrate 2. For example, the plurality of internal conductors 2C are formed of copper. Each of the internal conductors 2C electrically connects the corresponding conductive pads 2A and conductive pads 2B. Also, a first inductor L1 and a second inductor L2 are incorporated in the package substrate 2. The second inductor L1 is connected to an antenna pad Ant (not shown in FIG. 1) as described later. The second inductor L2 is connected to an antenna terminal AT.

[0017] The chip substrate 3 is mounted on the package substrate 2. For example, the chip substrate 3 is formed of a piezoelectric single crystal such as lithium tantalate, lithium niobate, or quartz. For example, the chip substrate 3 is formed of piezoelectric ceramics. For example, the chip substrate 3 is formed by bonding a piezoelectric substrate and a support substrate. For example, the support substrate is formed of sapphire, silicon, alumina, spinel, quartz, or glass.

[0018] For example, on the main surface (the lower surface in FIG. 1) of the chip substrate 3, a transmission filter and a reception filter are formed.

[0019] The transmission filter is formed so that an electrical signal in a desired frequency band can pass therethrough. For example, the transmission filter includes a ladder-type filter composed of a plurality of series resonators and a plurality of parallel resonators.

[0020] The reception filter is formed so that an electrical signal in a desired frequency band can pass therethrough. For example, the reception filter includes a ladder-type filter composed of a plurality of series resonators and a plurality of parallel resonators.

[0021] For example, the chip substrate 3 includes a wiring pattern 3A and a plurality of electrodes 3B. For example, the plurality of electrodes 3B are Interdigital Transducer (IDT) electrodes which are comb-shaped electrode fingers. The chip substrate 3 includes a notch resonator N1 (not shown in FIG. 1) as described later. The notch resonator N1 is connected to a notch pad Nt. The notch pad Nt is connected to a node between the first inductor L1 and the second inductor L2 via the bump 4 and the conductive pad 2A.

[0022] Each of the plurality of bumps 4 is made of gold, a conductive adhesive, solder, or the like. For example, the height of the bump 4 is from 20 μm to 50 μm. Each of the plurality of bumps 4 electrically connects the conductive pad 2A and the wiring pattern 3A at corresponding positions.

[0023] The sealing portion 5 hermetically seals the chip substrate 3 together with the package substrate 2 while leaving a space 6 between the package substrate 2 and the chip substrate 3. For example, the sealing portion 5 is formed of an insulator such as a synthetic resin. The synthetic resin is an epoxy resin, a polyimide, or the like.

[0024] Next, the configuration of the chip substrate 3 will be described with reference to FIG. 2. FIG. 2 is a view of the chip substrate seen from below after removing the wiring substrate in the surface acoustic wave device according to Embodiment 1.

[0025] The chip substrate 3 in FIG. 2 functions as a duplexer. As shown in FIG. 2, the wiring pattern 3A and the plurality of surface acoustic wave elements 7 are formed on the main surface of the chip substrate 3.

[0026] For example, the wiring pattern 3A is formed of a metal or alloy such as silver, aluminum, copper, titanium, palladium, etc. For example, the wiring pattern 3A is formed by laminating a plurality of metal layers. For example, the thickness of the wiring pattern 3A is from 150 nm to 400 nm.

[0027] The wiring pattern 3A includes four ground pads Gnd, an antenna pad Ant, a transmission pad Tx, a reception pad Rx, and a notch pad Nt. These bump pads are portions that are electrically connected to the bumps 4 (not shown in FIG. 2).

[0028] The plurality of surface acoustic wave elements 7 includes a plurality of series resonators S1, S2, S3, S4, a plurality of parallel resonators P1, P2, P3, and a notch resonator N1. The plurality of series resonators S1, S2, S3, S4, the plurality of parallel resonators P1, P2, P3, and the notch resonator N1 are electrically connected via the wiring pattern 3A.

[0029] The plurality of series resonators S1, S2, S3, S4, the plurality of parallel resonators P1, P2, P3, and the notch resonator N1 function as a transmission filter TF. Specifically, when a high-frequency electrical signal is input to the transmission pad Tx, the electrical signal passes through the plurality of series resonators S1, S2, S3, S4, the plurality of parallel resonators P1, P2, P3, and the notch resonator N1. At this time, only the electrical signal in the desired frequency band reaches the antenna pad Ant. As a result, only the electrical signal in the desired frequency band is output from the antenna pad Ant.

[0030] Although not shown in detail, the receiving filter Rx is also composed of a plurality of series resonators, a plurality of parallel resonators, etc., similar to the transmitting filter TF. When a high-frequency electrical signal is input to the antenna pad Ant, the electrical signal passes through a plurality of series resonators, a plurality of parallel resonators, etc. At this time, only the electrical signal in the desired frequency band reaches the receiving pad Rx. As a result, only the electrical signal in the desired frequency band is output from the receiving pad Rx.

[0031] Next, a first example of the elastic wave element 7 will be described with reference to FIG. 3. FIG. 3 is a diagram showing a first example of the elastic wave element of the elastic wave device in the first embodiment.

[0032] In FIG. 3, the elastic wave element 7 is a SAW (Surface Acoustic Wave) resonator. As shown in FIG. 3, a pair of IDT electrodes 7A and a pair of reflectors 7B are formed on the main surface of the chip substrate 3. The pair of IDT electrodes 7A and the pair of reflectors 7B are provided so as to be able to excite surface elastic waves.

[0033] For example, the pair of IDT electrodes 7A and the pair of reflectors 7B are formed of an alloy of aluminum and copper. For example, the pair of IDT electrodes 7A and the pair of reflectors 7B are formed of an appropriate metal such as titanium, palladium, silver, or an alloy thereof. For example, the pair of IDT electrodes 7A and the pair of reflectors 7B are formed of a laminated metal film in which a plurality of metal layers are laminated.

[0034] The IDT electrode 7A includes a plurality of electrode fingers 7D and a bus bar 7E. The plurality of electrode fingers 7D are arranged with their longitudinal directions aligned. The bus bar 7E connects the plurality of electrode fingers 7D so as to face each other. One of the pair of reflectors 7B is adjacent to one side of the pair of IDT electrodes 7A. The other of the pair of reflectors 7B is adjacent to the other side of the pair of IDT electrodes 7A. For example, the pair of IDT electrodes 7A and the pair of reflectors 7B are formed and patterned by the same process as the wiring pattern 3A (not shown in FIG. 3).

[0035] Next, a second example of the elastic wave element 7 will be described with reference to FIG. 4. FIG. 4 is a diagram showing a second example of the elastic wave element of the elastic wave device in the first embodiment.

[0036] In FIG. 4, the elastic wave element 7 is an acoustic thin film resonator. For example, the chip substrate 3 is a semiconductor substrate such as silicon, or an insulating substrate such as sapphire, alumina, spinel, or glass. The piezoelectric film 7F is provided on the main surface of the chip substrate 3. For example, the piezoelectric film 7F is formed of aluminum nitride. The lower electrode 7G and the upper electrode 7H are provided so as to sandwich the piezoelectric film 7F. For example, the lower electrode 7G and the upper electrode 7H are formed of a metal such as ruthenium. The gap 7J is formed between the lower electrode 7G and the chip substrate 3. In the acoustic thin film resonator, the lower electrode 7G and the upper electrode 7H excite an elastic wave in the thickness longitudinal vibration mode inside the piezoelectric film 7F.

[0037] Next, the connection relationship of the resonators will be described with reference to FIG. 5. FIG. 5 is a circuit diagram corresponding to the main part of the elastic wave device in the first embodiment.

[0038] As shown in FIG. 5, the package substrate 2 includes an antenna terminal AT, a transmission terminal TT, and a reception terminal RT as the conductive pads 2B in FIG. 1. The antenna terminal AT has a function of exchanging signals with the antenna pad Ant. The transmission terminal TT has a function of outputting an amplified signal toward the transmission pad Tx. The reception terminal RT has a function of receiving an input of a signal from the reception pad Rx.

[0039] Furthermore, the package substrate 2 includes a first inductor L1 and a second inductor L2. The first inductor L1 and the second inductor L2 are connected in series. The first inductor L1 is connected to the antenna pad Ant via the conductive pad 2A and the bump 4. The second inductor L2 is connected to the antenna terminal AT.

[0040] In the chip substrate 3, the notch resonator N1 has a resonance frequency that is higher than the frequency band of the ladder filter. The notch resonator N1 is connected to a node between any one of a plurality of parallel resonators and the ground pad Gnd. In FIG. 5, the notch resonator N1 is connected to a node between the parallel resonator P2 and the ground pad Gnd.

[0041] In the chip substrate 3, the notch pad Nt is not connected to resonators other than the notch resonator N1. That is, in the chip substrate 3, the notch pad Nt is connected only to the notch resonator N1. The notch resonator N1 is connected to a node between the first inductor L1 and the second inductor L2 via the notch pad Nt, the bump 4, and the conductive pad 2A.

[0042] Next, the characteristics of the elastic wave device 1 will be described with reference to FIG. 6. FIG. 6 is a diagram showing simulation results of the characteristics of the elastic wave device in Embodiment 1 and the characteristics of a comparative example. The horizontal axis of FIG. 6 is the frequency. The vertical axis of FIG. 6 is the attenuation amount. A in FIG. 6 indicates the insertion loss. B in FIG. 6 indicates the frequency characteristics of a wide band.

[0043] In FIG. 6, X1 is the characteristic when the transmission filter TF of the elastic wave device 1 in Embodiment 1 is configured corresponding to band 8. X2 is the characteristic of a comparative example in which the notch resonator N1 is removed from the transmission filter TF corresponding to X1.

[0044] In A of FIG. 6, m1 indicates the lower limit (880 MHz) of the transmission band of band 8. m2 indicates the upper limit (915 MHz) of the transmission band of band 8. At m1, X1 is -2.02 dB. X2 is -2.35 dB. At m2, X1 is -2.08 dB. X2 is -2.13 dB.

[0045] In B of FIG. 6, m3 indicates 1.76 GHz, which is the second harmonic of the frequency of m1. At m3, X1 is -54.04 dB. X2 is -48.06 dB.

[0046] As shown in FIG. 6, the elastic wave device 1 in Embodiment 1 has an insertion loss substantially equivalent to that of the comparative example. In contrast, the elastic wave device 1 in Embodiment 1 attenuates more harmonic components as compared with the comparative example.

[0047] According to Embodiment 1 described above, the first inductor L1 is provided on the package substrate 2. The first inductor L1 is connected to the antenna pad Ant. The notch resonator N1 is provided on the chip substrate 3. The notch resonator N1 is connected to a node between any one of a plurality of parallel resonators and the ground pad Gnd. At this time, a matching circuit or the like is unnecessary. For this reason, it is possible to reduce the size of the elastic wave device 1 while attenuating the harmonic components of the amplified signal. As a result, the cost of the elastic wave device 1 can also be reduced.

[0048] Note that the notch resonator N1 may be directly connected to the ground pad Gnd. Also in this case, it is possible to reduce the size of the elastic wave device 1 while attenuating the harmonic components of the amplified signal.

[0049] Further, when a matching circuit including a low-pass filter and a notch filter is used, the characteristics of the duplex transmission filter and reception filter deteriorate due to the low Q values of the inductance and the capacitor. In contrast, according to the elastic wave device 1 of Embodiment 1, it is possible to obtain a duplex in which deterioration of the characteristics of the transmission filter and the reception filter is suppressed.

[0050] Also, only the notch resonator N1 is connected to the notch pad Nt. Also, the second inductor L2 is connected to the antenna terminal AT. Also, the notch resonator N1 is connected to a node between the first inductor L1 and the second inductor L2. For this reason, it is possible to more reliably attenuate the harmonic components of the amplified signal.

[0051] Embodiment 2. FIG. 7 is a view of the chip substrate as seen from below after removing the wiring substrate in the elastic wave device according to Embodiment 2. Note that the same reference numerals are given to the same or corresponding parts as those in Embodiment 1, and the description of such parts is omitted.

[0052] As shown in FIG. 7, the chip substrate 3 of Embodiment 2 is obtained by adding a capacitor C1 and a capacitor pad Cp to the chip substrate 3 of Embodiment 1.

[0053] Next, the connection relationship between the resonator and the capacitor C1 will be described with reference to FIG. 8. FIG. 8 is a circuit diagram corresponding to the main part of the elastic wave device in Embodiment 2.

[0054] As shown in FIG. 8, the capacitor C1 is connected between the antenna pad Ant and the series resonator S4 closest to the antenna pad among the plurality of series resonators. The capacitor C1 is connected to a node between the second inductor L2 and the antenna terminal AT via the capacitor Cp, the bump 4, and the conductive pad 2A.

[0055] Next, the characteristics of the elastic wave device 1 and the comparative example will be described with reference to FIG. 9. FIG. 9 is a diagram showing the simulation results of the characteristics of the elastic wave device in Embodiment 2 and the characteristics of the comparative example. The horizontal axis in FIG. 9 is the frequency. The vertical axis in FIG. 9 is the attenuation amount. A in FIG. 9 indicates the insertion loss. B in FIG. 9 indicates the frequency characteristics in a wide band.

[0056] In FIG. 9, X3 is the characteristic when the transmission filter TF of the elastic wave device 1 in Embodiment 2 is configured corresponding to band 8. X4 is the characteristic of the comparative example in which the notch resonator N1 and the capacitor C1 are removed from the transmission filter TF corresponding to X3.

[0057] In A of FIG. 9, m1 indicates the lower limit (880 MHz) of the transmission band of band 8. m2 indicates the upper limit (915 MHz) of the transmission band of band 8. At m1, X3 is -2.16 dB. X4 is -2.35 dB. At m2, X3 is -2.34 dB. X4 is -2.13 dB.

[0058] In B of FIG. 9, m3 indicates 1.76 GHz which is the second harmonic of the frequency of m1. m4 indicates 2.64 GHz which is the third harmonic of the frequency of m1. At m3, X3 is -59.75 dB. X4 is -48.06 dB. At m4, X3 is -61.74 dB. X4 is -52.46 dB.

[0059] As shown in FIG. 9, the surface acoustic wave device 1 in Embodiment 2 has an insertion loss substantially equivalent to that of the comparative example. In contrast, the surface acoustic wave device 1 in Embodiment 2 attenuates more second and third harmonics of the amplified signal as compared with the comparative example.

[0060] In Embodiment 2 described above, the capacitor C1 is connected between the antenna pad Ant and the series resonator S4 which is the closest to the antenna pad among the plurality of series resonators. The capacitor C1 is connected to the node between the second inductor L2 and the antenna terminal AT. Therefore, the second and third harmonics of the amplified signal can be more reliably attenuated.

[0061] Embodiment 3. FIG. 10 is a cross-sectional view of a module to which the surface acoustic wave device in Embodiment 3 is applied. Note that the same reference numerals are given to the same or corresponding parts as those in Embodiment 1 or Embodiment 2. The description of those parts is omitted.

[0062] In FIG. 10, the module 100 includes a wiring board 101, an integrated circuit component 102, a surface acoustic wave device 1, an inductor 103, and a sealing portion 104.

[0063] The wiring board 101 is equivalent to the package board 2 of the first embodiment. The integrated circuit component 102 is mounted inside the wiring board 101. The integrated circuit component 102 includes an amplifier PA, a switching circuit, and a low-noise amplifier. The surface acoustic wave device 1 is mounted on the main surface of the wiring board 101. The inductor 103 is mounted on the main surface of the wiring board 101. The inductor 103 is mounted for impedance matching. For example, the inductor 103 is an Integrated Passive Device (IPD). The sealing portion 104 seals a plurality of electronic components including the surface acoustic wave device 1.

[0064] In the module, the amplifier PA has a function of amplifying a signal input to the transmission terminal TT of the surface acoustic wave device 1.

[0065] According to the third embodiment described above, the module 100 includes the surface acoustic wave device 1. The amplifier PA amplifies a signal input to the transmission terminal TT of the surface acoustic wave device 1. Therefore, it is possible to reduce the size of the module 100 while attenuating the harmonic components of the amplified signal.

[0066] Although some aspects of at least one embodiment have been described, it should be understood that various modifications, corrections, and improvements will be readily envisioned by those skilled in the art. Such modifications, corrections, and improvements are intended to be part of the present disclosure and are intended to be within the scope of the present disclosure.

[0067] It should be understood that the embodiments of the methods and apparatuses described herein are not limited to the details of the structures and arrangements of the components described in the above description or illustrated in the accompanying drawings. The methods and apparatuses can be implemented in other embodiments and can be implemented or executed in various manners. The specific implementation examples are provided herein for illustrative purposes only and are not intended to be limiting.

[0068] The expressions and terms used in this disclosure are for illustrative purposes and should not be regarded as limiting. The use of "including", "comprising", "having", "containing" and their variants herein means the inclusion of the items listed hereinafter and their equivalents as well as additional items.

[0069] References to "or (alternatively)" can be construed such that any term described using "or (alternatively)" indicates one, more than one, and all of the terms described therein.

[0070] References to front and back, left and right, top and bottom, vertical and horizontal, front and back are all for the convenience of description. Such references do not limit the components of the present disclosure to any one positional or spatial orientation. Therefore, the above description and drawings are merely illustrative.

Description of Reference Numerals

[0071] 1 Elastic wave device, 2 Package substrate, 2A Conductive pad, 2B Conductive pad, 2C Internal conductor, 3 Chip substrate, 3A Wiring pattern, 3B Electrode, 4 Bump, 5 Sealing portion, 6 Space, 7 Elastic wave element, 7A IDT electrode, 7B Reflector, 7D Electrode finger, 7E Bus bar, 7F Piezoelectric film, 7G Lower electrode, 7H Upper electrode, 7J Gap, 100 Module, 101 Wiring substrate, 102 Integrated circuit component, 103 Inductor, 104 Sealing portion

Claims

1. A package substrate including a first inductor, a second inductor, an antenna terminal, a transmission terminal, and a reception terminal; A chip substrate mounted on the package substrate; A plurality of series resonators and a plurality of parallel resonators formed on the chip substrate and constituting a ladder-type filter; An antenna pad, a transmission pad, a reception pad, and a ground pad formed on the chip substrate; A notch resonator formed on the chip substrate and having a resonance frequency higher than the frequency band of the ladder-type filter; Comprising: The first inductor is connected to the antenna pad; The second inductor is connected to the antenna terminal; The notch resonator is a surface acoustic wave device connected to a node between any one of the plurality of parallel resonators, the first inductor, and the second inductor.

2. A notch pad formed on the chip substrate and to which only the notch resonator is connected; The surface acoustic wave device according to claim 1, comprising:

3. A capacitor formed on the chip substrate, connected between the antenna pad and the series resonator closest to the antenna pad among the plurality of series resonators, and connected to a node between the second inductor and the antenna terminal; The surface acoustic wave device according to claim 1, comprising:

4. A surface acoustic wave device according to any one of claims 1 to 3; An amplifier for amplifying a signal input to the transmission terminal; A module comprising:

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