WO2020108529A1

WO2020108529A1 - Duplexer

Info

Publication number: WO2020108529A1
Application number: PCT/CN2019/121258
Authority: WO
Inventors: 庞慰; 郑云卓
Original assignee: 天津大学; 诺思(天津)微系统有限责任公司
Priority date: 2018-11-28
Filing date: 2019-11-27
Publication date: 2020-06-04
Also published as: CN109831174A

Abstract

A duplexer having a packaging substrate, a wafer having a transmission filter fabricated thereon, and a wafer having a receiving filter fabricated thereon. The wafer having the transmission filter is packaged with the wafer having the transmission filter by means of wafer bonding, and the wafer having the transmission filter is connected to a top solder pad of the packaging substrate via solder balls. The transmission filter is connected between an antenna terminal and a transmission terminal, and consists of multiple first series-connection units connected in series and first parallel-connection units respectively connected to a position between each pair of adjacent first series-connection units in parallel. The receiving filter is connected between the antenna terminal and a receiving terminal, and consists of multiple second series-connection units connected in series and second parallel-connection units respectively connected to a position between each pair of adjacent second series-connection units in parallel. Coupling capacitors are connected between the first parallel-connection units of the transmission filter and the second parallel-connection units of the receiving filter.

Description

A duplexer

Technical field

The invention relates to the field of filter devices for communication, and in particular to a miniaturized duplexer manufactured using the principle of piezoelectric effect.

Background technique

With the approaching of the 5G communication era, wireless communication terminals and equipment continue to develop in the direction of miniaturization and multimode-multiband. The duplexer used for FDD (Frequency Division Multiplexing Duplex) in wireless communication terminals The number has also increased. Five-mode thirteen-band, and even five-mode seventeen-band are gradually becoming the standard requirements of mainstream mobile phones, and the demand for small-sized, high-performance duplexers such as Band1, 2, 3, 5, 7, and 8 is also increasing. .

At present, the small-sized filtering devices that can meet the needs of communication terminals are mainly piezoelectric acoustic wave filters. The resonators constituting such acoustic wave filters mainly include: FBAR (Film Bulk Acoustic Resonator), SMR (Solidly Mounted Resonator, solid-state mounted resonator) and SAW (Surface Acoustic Wave, surface acoustic wave resonator). Among them, filters based on the principle of bulk acoustic wave FBAR and SMR (collectively called BAW, bulk acoustic resonator), compared with filters based on the principle of surface acoustic wave SAW, have lower insertion loss, faster roll-off characteristics and other advantages However, because the planar etching process used by SAW is different, BAW is mainly made by thin film technology. Therefore, it is very difficult to make more than two filters on a silicon wafer by depositing different film thicknesses.

The general duplexer is made by packaging two filter chips. The duplexer formed by the two chips and the packaging substrate, due to the assembly process requires the spacing between the chips, results in low packaging efficiency, generally only 50% to 60%. However, if two wafers with filters are directly fabricated and bonded together using wafer-level sealing, the isolation performance of the duplexer will be very poor due to electromagnetic coupling, and the isolation is only -30dB～-40dB. Too much performance degradation makes it unusable.

Therefore, how to design a duplexer composed of a single chip formed by bonding two wafers with separate filters and having a good transmission and receiving isolation is still a technical problem to be solved.

Summary of the invention

In view of this, the present invention provides a duplexer, which can bond two wafers of separate manufacturing filters together to form a single chip, while achieving better isolation characteristics.

The first object of the present invention is to provide a duplexer having an antenna terminal, a transmission terminal and a reception terminal,

The duplexer has:

A transmission filter, which is connected between the antenna terminal and the transmission terminal, is composed of a plurality of first series units connected in series and a first parallel unit respectively connected in parallel between each adjacent two first series units;

A receiving filter, which is connected between the antenna terminal and the receiving terminal, is composed of a plurality of second series units connected in series and a second parallel unit respectively connected in parallel between each adjacent two second series units; with

A coupling capacitor is connected between the ground terminal of any first parallel unit in the transmission filter and the ground terminal of any second parallel unit in the reception filter.

The second object of the present invention is to provide a duplexer having an antenna terminal, a transmission terminal and a reception terminal,

The duplexer has:

A coupling capacitor connected between the non-ground terminal of the first parallel unit near the antenna terminal in the transmission filter and the non-ground terminal of the second parallel unit near the antenna terminal in the reception filter.

The third object of the present invention is to provide a duplexer having an antenna terminal, a transmission terminal and a reception terminal,

The duplexer has:

A coupling capacitor is connected between the ground terminal of any first parallel unit in the transmission filter and the non-ground terminal of the second parallel unit in the reception filter close to the antenna terminal.

The fourth object of the present invention is to provide a duplexer having an antenna terminal, a transmission terminal and a reception terminal,

The duplexer has:

A coupling capacitor is connected between the non-ground terminal of the first parallel unit near the antenna terminal in the transmission filter and the ground terminal of any second parallel unit in the reception filter.

A fifth object of the present invention is to provide a duplexer. In addition to the above structure, the duplexer also has:

A package substrate having an upper surface on which top pads are installed, and a lower surface on which bottom pads are installed,

Making the wafer with the transmission filter connected to the top pad of the package substrate through solder balls;

The wafer on which the reception filter is fabricated is connected to the wafer on which the transmission filter is fabricated through wafer bonding.

In the present invention, a wafer made with a transmission filter and a wafer wafer made with a reception filter are bonded together to form a single chip, so that the volume of the duplexer is greatly reduced, and in the parallel resonator of the transmission filter Connect a coupling capacitor between the parallel resonator of the receiving filter and change the out-of-band suppression points of the transmission filter and the receiving filter. The coupling capacitor can move the out-of-band suppression points of the two filters to an appropriate position, thereby improving The isolation between the duplexers is increased.

BRIEF DESCRIPTION

The drawings are used for a better understanding of the present invention and do not constitute an improper limitation of the present invention. among them:

Figure 1 is a schematic diagram of the structure of the existing duplexer;

Figure 2 is a schematic front view of the assembly of the existing duplexer;

3 is a circuit schematic diagram of the existing duplexer;

4 is a schematic circuit diagram of a duplexer according to an embodiment;

5 is a schematic front view of the assembly of a duplexer of an embodiment:

5(a) is a schematic front view of a wafer assembly with a Tx filter;

Figure 5(b) is a schematic front view of the wafer assembly with Rx filter;

Figure 5(c) is a schematic front view of the duplexer chip assembly;

5(d) is a perspective view of the duplexer chip viewed from the side of the Tx wafer;

FIG. 5(e) is a schematic diagram of the duplexer chip assembled in the package substrate;

6 is a circuit schematic diagram of the duplexer of the second embodiment;

7 is a simulation result diagram of the duplexer circuit of the second embodiment;

8 is a circuit schematic diagram of the duplexer of the third embodiment;

9 is a simulation result diagram of the duplexer circuit of the third embodiment;

10 is a circuit schematic diagram of the duplexer of the fourth embodiment;

FIG. 11 is a simulation result diagram of the duplexer circuit of the fourth embodiment;

12 is a circuit schematic diagram of the duplexer of the fifth embodiment;

13 is a simulation result diagram of the duplexer circuit in the fifth embodiment;

14 is a schematic front view of the assembly of the duplexer of the sixth embodiment

15 is a schematic front view of the assembly of the duplexer of the seventh embodiment.

detailed description

The present invention will be further described below with reference to the drawings and embodiments.

FIG. 1 is a schematic diagram of a conventional duplexer 100 fabricated in a two-chip package. The duplexer 100 includes a receiving filter chip 101 and a transmitting filter chip 102. The two chips are connected to the surface pad 114 of the package substrate 110 through a solder ball 108 using a flip chip (flip chip) method. The via 116 located inside the package substrate is connected to the pad 116 located on the bottom surface of the package substrate. The receiving filter chip 101 includes a device wafer 103 fabricated with a resonator 105 and a package wafer 104 fabricated with a via 109. 103 and 104 are closely connected to each other through a bonding region 107 using a wafer bonding process together. Depending on the graphic design, the bonding area 107 has two functions: one is to conduct the circuit on the wafer 103 to the wafer 104, and then to the outside of the chip through the through hole 109; the second is to close the chip The outer edge area forms a closed ring structure to protect the inner chip from the external environment. Similarly, in the transmission filter chip 102, a resonator 106 is fabricated. The

resonators

105 and 106 may be FBAR or SMR.

2 is a schematic front view of the assembly of the existing duplexer 200, where 210 is the package substrate; 201 is the receiving filter chip; 202 is the transmitting filter chip; 208 is the pad on the chip, generally a grounding pad or signal Pad. The ground pad is generally directly connected to the ground of the package substrate, or according to the circuit design, connected to the ground through an inductor or a transmission line, and connected to the ground pad on the bottom surface of the package substrate, which are not shown in the figure. The signal pad on the chip is connected to the signal port on the bottom surface of the package substrate through the traces and vias 212 in the package substrate: 216 in the figure is the antenna port of the duplexer, 217 is the receiving port of the duplexer, and 218 is the duplex The sending port of the tool.

FIG. 3 is a circuit schematic diagram of the existing duplexer 300, where 302 is an antenna port. 304 is the Rx port. Between 302 and 304 is a series of series resonators and parallel resonators composed of a ladder structure Rx filter. 306 is the Tx port. Located between 302 and 306 is a series of Tx filters composed of series resonators and parallel resonators.

The duplexer formed by the two chips and the packaging substrate mentioned above, because the assembly process requires the spacing between the chips, results in low packaging efficiency, generally only 50% to 60%. However, if two wafers with filters are directly fabricated and bonded together using wafer-level sealing, the performance of the duplexer will become very poor due to electromagnetic coupling, and the isolation is only -30dB～-40dB, and the performance will decrease. Too much to use.

In order to solve the above-mentioned technical problems, the present invention proposes a miniaturized duplexer, which can bond two wafers of separate manufacturing filters together to form a single chip, while achieving better isolation characteristics.

This embodiment provides a miniaturized duplexer. As shown in FIG. 4, the duplexer includes a packaging substrate 402, a wafer 401 fabricated with (2620MHz-2690MHz) receiving filters, and a transmission fabricated with (25000MHz-2570MHz) Filter wafer 403.

The wafer 401 made with the receiving filter and the wafer 403 made with the transmitting filter are packaged together by wafer bonding. The outermost of the two have a common sealing ring 407, and the distance between the two wafers It is 2um-15um.

The packaging substrate 402 has an upper surface on which the top pad 404 is installed, and a lower surface on which the bottom pad is installed, the wafer 401 on which the receiving filter chip is fabricated and the crystal on which the transmitting filter chip is fabricated After the circles 403 are packaged together, the wafer 403 on which the transmission filter chip is fabricated is connected to the top pad 404 of the packaging substrate 402 through solder balls 408.

In this embodiment, the upper electrode of a certain parallel resonator in the wafer 401 on which the reception filter is fabricated and the upper electrode of a certain parallel resonator in the wafer 403 on which the transmission filter is fabricated have a certain vertical The overlapped area, thereby forming a coupling capacitor 430. The area of the parallel resonators of the receiving filter and the transmitting filter is about 25000um ² , and the overlapping area is 23000um ² . The general calculation formula of the capacitor is:

C=ε ₀ *ε _r *S/d

Where ε ₀ is the vacuum dielectric constant, ε _r is the relative dielectric constant of the dielectric air between the electrodes, S is the overlapping area of the two resonator electrodes, and d is the distance between the two wafers, which can be calculated The capacitance of this capacitor is about 0.1pF. Other resonators do not have similar overlapping areas.

FIG. 5 is a schematic diagram of an implementation scheme of the duplexer. FIG. 5(a) is a schematic diagram of a wafer with a transmission filter, viewed from above the device fabrication surface, and FIG. 5(b) is a wafer with a reception filter. , A schematic view from above the device fabrication surface, where the black rectangular area is the bonding area for wafer-level package bonding, connected to the via hole on the wafer where the transmission filter is made, and the outer ring is ring-shaped The structure is a sealing ring. Turn the wafer with the transmission filter made in 5(a) upside down, and perform wafer bonding with the wafer with the reception filter, to obtain the duplexer chip of FIG. 5(c). On the back side of the wafer that transmits the filter, the die pad is also connected to the via. Figure 5(d) is a perspective view of the duplexer chip from the side of the wafer where the transmission filter is made. The name of each resonator is marked in the figure, T represents Tx, R represents Rx, S represents the series position, P Represents the parallel position, and the number represents the order position corresponding to the filter. FIG. 5(e) is a schematic diagram of a duplexer chip assembled in a package substrate, specifically showing two resonator regions forming a capacitor.

The circuit structure of the duplexer proposed in this embodiment has various forms, specifically as follows:

Example one

FIG. 6 is a circuit diagram of the duplexer of this embodiment. As shown in FIG. 6, the duplexer has an antenna terminal 502, a transmission terminal 506, and a reception terminal 504. The duplexer further includes a transmission filter and a reception filter, and the transmission filter is connected to the antenna terminal 502 Between the transmission terminal 506 and the reception filter, the antenna filter 502 and the reception terminal 504 are connected.

Specifically, the transmission filter includes a plurality of first series units connected in series, and first parallel units respectively connected in parallel between each adjacent two first series units, the first series units including at least one first series Resonator, the first parallel unit includes a first parallel resonator and a first grounded inductor connected in series; one end of the first parallel resonator is connected between every two adjacent first series resonators, and the other end is connected to the first ground Inductive connection, the other end of the first grounding inductor is grounded.

The receiving filter includes a plurality of second series units connected in series, and a second parallel unit connected in parallel between each two adjacent second series units, the second series unit including at least one second series resonator, The second parallel unit includes a second parallel resonator and a second ground inductor connected in series; one end of the second parallel resonator is connected between every two adjacent second series resonators, and the other end is connected to the second ground inductor, The other end of the second grounding inductor is grounded.

A coupling capacitor C is connected between the first parallel unit of the transmitting filter and the second parallel unit of the receiving filter, a node between one end of the coupling capacitor C and the first parallel resonator and the first inductor in the first parallel unit The other end of the coupling capacitor C is connected to the node between the second parallel resonator and the second inductor in the second parallel unit.

In this embodiment, the capacitance of the coupling capacitor C is about 0.1 pF. Since the capacitor is connected to the ground terminals of two parallel resonators forming out-of-band suppression, when the two grounding inductances are greater than 0.2 nH, the capacitor C and Two grounding inductors form an LC resonant circuit, changing the out-of-band suppression points of the transmit filter and receive filter. When the capacitance value is more suitable, such as the capacitance value of the coupling capacitor C in this embodiment is 0.1 pF, the out-of-band suppression points of the transmission filter and the reception filter can be moved to an appropriate position, thereby improving the duplexer Isolation.

Fig. 7 is the simulation result of the duplexer circuit diagram shown in Fig. 6, and it can be seen that at 2500MHz, the isolation of the duplexer is improved by 4dB, while the isolation at other locations is not significantly deteriorated.

Example 2

FIG. 8 is a circuit diagram of the duplexer of this embodiment. As shown in FIG. 8, the duplexer has an antenna terminal 502, a transmission terminal 506, and a reception terminal 504. The duplexer further includes a transmission filter and a reception filter, and the transmission filter is connected to the antenna terminal 502 Between the transmission terminal 506 and the reception filter, the antenna filter 502 and the reception terminal 504 are connected.

A coupling capacitor C is connected between a node between the first two first series units near the antenna end of the transmit filter and a node between the first two second series units near the antenna end of the receive filter One end of the capacitor C is connected to the node between the first two first series units near the antenna end of the transmission filter, and the other end is connected to the node between the first two second series units near the antenna end of the reception filter.

In this embodiment, the capacitance value of the capacitor is still 0.1 pF. FIG. 9 is the simulation result corresponding to FIG. 8, and it can be seen that the improved isolation is weaker.

Example Three

FIG. 10 is a circuit diagram of the duplexer of this embodiment. As shown in FIG. 10, the duplexer has an antenna terminal 502, a transmission terminal 506, and a reception terminal 504. The duplexer further includes a transmission filter and a reception filter. The transmission filter is connected to the antenna terminal 502 Between the transmission terminal 506 and the reception filter, the antenna filter 502 and the reception terminal 504 are connected.

A coupling capacitor C is connected between a node between two adjacent second series resonators of the receiving filter and the first parallel unit of the transmitting filter, and one end of the coupling capacitor C is adjacent to two adjacent second The node between the two series resonators is connected, and the other end of the coupling capacitor C is connected to the node between the first parallel resonator and the first inductor in the first parallel unit of the transmission filter.

The capacitor C of FIG. 10 is connected to the non-ground terminal of the second parallel unit and the ground terminal of the first parallel unit. The capacitance value of the capacitor C is still 0.1 pF. FIG. 11 is the simulation result corresponding to FIG. 10, at 2650MHz～2690MHz. The isolation is slightly better.

Example 4

FIG. 12 is a circuit diagram of the duplexer of this embodiment. As shown in FIG. 12, the duplexer has an antenna terminal 502, a transmission terminal 506, and a reception terminal 504, the duplexer further includes a transmission filter and a reception filter, and the transmission filter is connected to the antenna terminal Between 502 and the transmission terminal 506, the reception filter is connected between the antenna terminal 502 and the reception terminal 504.

A coupling capacitor C is connected between a node between two adjacent first series resonators near the antenna end of the receiving filter and the first parallel unit near the antenna end of the transmitting filter, and one end of the coupling capacitor C and the receiving filter The node between two adjacent first series resonators near the antenna end in the middle, the other end of the coupling capacitor C is connected to the node between the first parallel resonator and the first inductor in the first parallel unit near the antenna end in the transmission filter .

In FIG. 12, the capacitor C is connected between the non-ground terminal of the first second parallel unit RP1 of the receiving filter and the ground terminal of the first first parallel unit TP1 of the transmitting filter. FIG. 13 corresponds to the circuit diagram shown in FIG. The simulation results show that the isolation at 2500MHz has hardly changed, but the worst value of the isolation from 2620MHz to 2690MHz has increased from 61dB (at 2690MHz) to 64.5dB (at 2630MHz).

Example 5

14 is a schematic front view of the assembly of the duplexer of this embodiment. As shown in FIG. 14, the duplexer has an antenna terminal, a transmission terminal, and a reception terminal. The duplexer further includes a transmission filter and a reception filter. The transmission filter is connected between the antenna terminal and the Between the transmission terminals, the reception filter is connected between the antenna terminal and the reception terminal; the circuit structure of the transmission filter and the reception filter is the same as the transmission filter and the reception filter in the first to fifth embodiments The circuit structure of the device is the same and will not be repeated here. The two left and right dashed boxes in FIG. 14 respectively show the approximate area of the circuit with the resonator and the like on the wafer with the receiving filter and the circuit with the resonator and the circuit on the wafer with the transmitting filter. Area, there is a partial overlap between the two areas.

A coupling capacitor C is connected between the second parallel unit near the antenna end in the receiving filter and the first parallel unit in the transmitting filter, one end of the coupling capacitor C and the second parallel unit in the receiving filter near the antenna end The ground terminal of the parallel resonator RP1 is connected, and the other end of the coupling capacitor C is connected to the ground terminal of the first parallel resonator in the first parallel unit in the transmission filter TP3.

The difference between the duplexer of this example and the duplexer of the above embodiment is that instead of directly using the electrode overlapping area of the resonator as a capacitor, the vertical direction between the two metal plates connected to the ground terminal is The overlap area is used to make the capacitor, so that the two metal sheets can be located on two wafers, and the medium in the middle of the overlap area is air; it can also be located on a wafer (such as a wafer with a receiving filter) ), the middle of the overlapping area of the metal sheet can be made of other dielectric film layers, the material of the medium can be silicon dioxide, or other dielectric property materials, made of dielectric materials, an advantage over air is that it can be obtained Greater electrical capacity.

Example Six

15 is a schematic front view of the assembly of the duplexer of this embodiment. As shown in FIG. 15, the duplexer has an antenna terminal, a transmission terminal, and a reception terminal. The duplexer further includes a transmission filter and a reception filter. The transmission filter is connected to the antenna terminal and the transmission Between the terminals, the receiving filter is connected between the antenna terminal and the receiving terminal; the circuit structure of the transmitting filter and the receiving filter is the same as the transmitting filter and the receiving filter in the first to fifth embodiments The circuit structure of the circuit is the same and will not be repeated here. The two left and right dashed boxes in FIG. 15 respectively show the approximate area of the circuit with the resonator and the like on the wafer with the receiving filter and the circuit with the resonator and the circuit on the wafer with the transmitting filter. region.

A coupling capacitor C is connected between the first parallel resonator TP2 of the transmission filter and the second parallel resonator RP2 of the reception filter. Due to the long distance, the ground terminal of the second parallel resonator RP2 is connected to the sealing ring At the same time, two metal sheets are made in the area near the first parallel resonator TP2 at the same time to realize the capacitance. Between the receiving filter and the transmitting filter, make a long bonding area to separate the two sides, reducing the coupling capacitance that is not conducive to performance.

In summary, the duplexer proposed in this embodiment can connect the coupling capacitor to the ground of any two parallel resonators of the transmission filter and the reception filter, and can set the coupling capacitor on the two parallel resonators. There is no ground terminal, and both parallel resonators are parallel resonators close to the antenna terminal; if one end of the coupling capacitor is connected to the ground terminal of the parallel resonator and the other end is connected to the non-ground terminal of the parallel resonator, then the non-ground terminal The parallel resonator can only be the parallel resonator closest to the antenna port, and the parallel resonator farther away from the antenna port will not work.

From the above technical solutions, it can be concluded that the beneficial effects achieved by the present invention are:

Although the specific embodiments of the present invention have been described above with reference to the drawings, it does not limit the protection scope of the present invention. Those skilled in the art should understand that based on the technical solutions of the present invention, those skilled in the art do not need to pay creative labor The various modifications or deformations that can be made are still within the protection scope of the present invention.

Claims

A duplexer having an antenna terminal, a transmission terminal and a reception terminal, characterized by

The duplexer has:

A transmission filter, which is connected between the antenna terminal and the transmission terminal, is composed of a plurality of first series units connected in series and a first parallel unit respectively connected in parallel between each adjacent two first series units;

A receiving filter, which is connected between the antenna terminal and the receiving terminal, is composed of a plurality of second series units connected in series and a second parallel unit respectively connected in parallel between each adjacent two second series units; with

A coupling capacitor is connected between the ground terminal of any first parallel unit in the transmission filter and the ground terminal of any second parallel unit in the reception filter.
A duplexer having an antenna terminal, a transmission terminal and a reception terminal, characterized by

The duplexer has:

A transmission filter, which is connected between the antenna terminal and the transmission terminal, is composed of a plurality of first series units connected in series and a first parallel unit respectively connected in parallel between each adjacent two first series units;

A receiving filter, which is connected between the antenna terminal and the receiving terminal, is composed of a plurality of second series units connected in series and a second parallel unit respectively connected in parallel between each adjacent two second series units; with

A coupling capacitor connected between the non-ground terminal of the first parallel unit near the antenna terminal in the transmission filter and the non-ground terminal of the second parallel unit near the antenna terminal in the reception filter.
A duplexer having an antenna terminal, a transmission terminal and a reception terminal, characterized by

The duplexer has:

A transmission filter connected between the antenna terminal and the transmission terminal, and composed of a plurality of first series units connected in series and first parallel units connected in parallel between each adjacent two first series units;

A receiving filter, which is connected between the antenna terminal and the receiving terminal, is composed of a plurality of second series units connected in series and a second parallel unit respectively connected in parallel between each adjacent two second series units; with

A coupling capacitor is connected between the ground terminal of any first parallel unit in the transmission filter and the non-ground terminal of the second parallel unit in the reception filter close to the antenna terminal.
A duplexer having an antenna terminal, a transmission terminal and a reception terminal, characterized by

The duplexer has:

A transmission filter, which is connected between the antenna terminal and the transmission terminal, is composed of a plurality of first series units connected in series and a first parallel unit respectively connected in parallel between each adjacent two first series units;

A receiving filter, which is connected between the antenna terminal and the receiving terminal, is composed of a plurality of second series units connected in series and a second parallel unit respectively connected in parallel between each adjacent two second series units; with

A coupling capacitor is connected between the non-ground terminal of the first parallel unit near the antenna terminal in the transmission filter and the ground terminal of any second parallel unit in the reception filter.
A duplexer according to any one of claims 1 to 4, wherein the first series unit includes at least one first series resonator, and the first parallel unit includes a series connected first A parallel resonator and a first grounding inductor; one end of the first parallel resonator is connected between each adjacent two first series resonators, the other end is connected to the first grounding inductor, and the other end of the first grounding inductor is grounded .
A duplexer according to any one of claims 1 to 4, wherein the second series unit includes at least one second series resonator, and the second parallel unit includes a second series connected A parallel resonator and a second grounding inductor; one end of the second parallel resonator is connected between each adjacent two second series resonators, the other end is connected to the second grounding inductor, and the other end of the second grounding inductor is grounded .
A duplexer according to any one of claims 1 to 4, wherein the coupling capacitor is composed of a capacitor element provided on a substrate.
A duplexer according to any one of claims 1 to 4, wherein the duplexer further has:

A package substrate having an upper surface on which top pads are installed, and a lower surface on which bottom pads are installed,

Making the wafer with the transmission filter connected to the top pad of the package substrate through solder balls;

The wafer on which the reception filter is fabricated is connected to the wafer on which the transmission filter is fabricated through wafer bonding.
The duplexer according to claim 8, wherein a sealing ring is provided on the outer side of the wafer with the transmission filter and the wafer with the receiving filter, between the two wafers The spacing is 2um-15um.