Disclosure of Invention
In order to overcome the defects in the prior art, the invention provides a bulk acoustic wave duplexer to improve the critical band inhibition and isolation of the bulk acoustic wave duplexer.
In order to achieve the aim of the invention, the invention adopts the following technical scheme:
A bulk acoustic wave duplexer, comprising:
a packaging substrate, the upper surface of which is provided with a metal layer;
A transmit filter wafer disposed over the package substrate, including at least two resonators; a first MIM capacitor is formed between the resonator of the transmitting filter wafer and the upper surface metal layer of the packaging substrate;
A receiving filter wafer disposed above the package substrate and coplanar with the transmitting filter wafer, comprising at least two resonators; and a second MIM capacitor is formed between the resonator of the receiving filter wafer and the upper surface metal layer of the packaging substrate, and the second MIM capacitor is electrically connected with the first MIM capacitor through the upper surface metal layer of the packaging substrate.
Further, the upper surface metal layer of the package substrate specifically includes:
The first metal layer and the second metal layer are arranged in a cross shape, and a plurality of third metal layers are arranged outside the first metal layer and the second metal layer;
The first metal layer forms a first MIM capacitor and a second MIM capacitor with the resonator of the transmitting filter wafer and the resonator of the receiving filter wafer respectively, and the first MIM capacitor is electrically connected with the second MIM capacitor;
the second metal layer is arranged between the transmitting filter wafer and the receiving filter wafer in a non-contact manner with the first metal layer;
The third metal layer is electrically connected with the grounding ends of the transmitting filter wafer and the receiving filter wafer.
Further, the transmit filter wafer specifically includes:
a transmission filter having a ladder structure formed by a plurality of series resonators and parallel resonators; wherein each of the series resonator and the parallel resonator includes a substrate, and a bottom electrode, a piezoelectric layer, and a top electrode disposed over the substrate.
Further, in the transmission filter,
The antenna port is connected with the top electrode of the adjacent series resonator, the bottom electrode of the series resonator is connected with the bottom electrodes of the adjacent series resonator and the parallel resonator, and the top electrode of the adjacent series resonator is connected with the top electrodes of the adjacent series resonator and the parallel resonator;
Or the antenna port is connected to the bottom electrode of an adjacent series resonator, the top electrode of which is connected to the top electrodes of its adjacent series resonator and parallel resonator, and the bottom electrode of which is connected to the bottom electrodes of its adjacent series resonator and parallel resonator.
Further, the receiving filter wafer specifically includes:
A reception filter having a ladder structure formed by a plurality of series resonators and parallel resonators; wherein each of the series resonators and the parallel resonators includes a substrate, and a bottom electrode and a top electrode disposed over the substrate.
Further, in the receiving filter,
The antenna port is connected with the top electrode of the adjacent series resonator, the bottom electrode of the series resonator is connected with the bottom electrodes of the adjacent series resonator and the parallel resonator, and the top electrode of the adjacent series resonator is connected with the top electrodes of the adjacent series resonator and the parallel resonator;
Or the antenna port is connected to the bottom electrode of an adjacent series resonator, the top electrode of which is connected to the top electrodes of its adjacent series resonator and parallel resonator, and the bottom electrode of which is connected to the bottom electrodes of its adjacent series resonator and parallel resonator.
Further, the top electrode or the bottom electrode of the parallel resonator is electrically connected with the third metal layer on the upper surface of the packaging substrate through a solder ball.
Further, the third metal layer on the upper surface of the package substrate is connected to the lower surface metal layer of the package substrate through a via hole or a wire winding inductance in the package substrate.
The invention has the following beneficial effects:
According to the invention, the MIM capacitor is formed between the resonator top electrode and the packaging substrate, and the sizes and positions of the MIM capacitors C1 and C2 are adjusted, so that the out-of-band suppression points of the transmitting filter and the receiving filter are changed and moved to the required positions under the condition that more layers of substrates are not added and discrete components are not introduced, and the isolation degree of the duplexer is improved.
Detailed Description
The following description of the embodiments of the present invention is provided to facilitate understanding of the present invention by those skilled in the art, but it should be understood that the present invention is not limited to the scope of the embodiments, and all the inventions which make use of the inventive concept are protected by the spirit and scope of the present invention as defined and defined in the appended claims to those skilled in the art.
As shown in fig. 1, an embodiment of the present invention provides a bulk acoustic wave duplexer, including:
a packaging substrate, the upper surface of which is provided with a metal layer;
a transmit filter wafer disposed over the package substrate, including at least two resonators; a first MIM capacitor is formed between the resonator of the transmitting filter wafer and the upper surface metal layer of the packaging substrate;
a receiving filter wafer disposed above the package substrate and coplanar with the transmitting filter wafer, comprising at least two resonators; a second MIM capacitor is formed between the resonator of the receiving filter wafer and the upper surface metal layer of the packaging substrate, and the second MIM capacitor is electrically connected with the first MIM capacitor through the upper surface metal layer of the packaging substrate.
In the art, a conventional duplexer generally employs a metal seal ring to bond together a filter Wafer and a package Wafer (Cap Wafer) through a Wafer Level Package (WLP), and the metal seal ring and a resonator FBAR on the filter Wafer are electrically connected to a pattern corresponding to an upper surface of a metal layer of a package substrate through a via hole of the package Wafer in a flip-chip manner.
The invention adopts a packaging mode of removing Wafer Level Packaging (WLP), directly welds the filter wafer to the upper surface of the packaging substrate in a flip-chip mode through solder balls, and then connects the filter wafer to the lower surface of the packaging substrate through a through hole or a wire winding inductor in the packaging substrate. The packaging mode adopted by the invention can reduce packaging links, shorten research and development period and greatly reduce research and development cost because the packaging wafer for wafer level packaging is removed; secondly, the packaging wafer is reduced, and the transmitting filter wafer and the receiving filter wafer are welded on the upper surface of the packaging substrate in a coplanar manner, so that the height of the device is greatly reduced, and the chip volume is reduced; finally, the filter wafer is directly welded on the upper surface of the packaging substrate in a flip-chip manner through the solder balls, so that metal through holes on the packaging wafer are removed, and the device loss is optimized.
And, the invention forms MIM (Metal-Insulator-Metal) capacitor between resonator and packaging substrate, and makes it integrated at specific position of duplexer of ladder structure by specific connection mode, thus realizing coupling capacitance between parallel resonator of transmitting filter and parallel resonator of receiving filter without adding more layers of substrate and introducing discrete components, changing out-of-band suppression point of transmitting filter and receiving filter, moving it to required position, so as to improve isolation degree of duplexer.
In an alternative embodiment of the present invention, as shown in fig. 2, the metal layer disposed on the upper surface of the package substrate of the present invention specifically includes:
The first metal layer and the second metal layer are arranged in a cross shape, and a plurality of third metal layers are arranged outside the first metal layer and the second metal layer;
The first metal layer forms a first MIM capacitor and a second MIM capacitor with the resonator of the transmitting filter wafer and the resonator of the receiving filter wafer respectively, and the first MIM capacitor is electrically connected with the second MIM capacitor;
the second metal layer is arranged between the transmitting filter wafer and the receiving filter wafer in a non-contact manner with the first metal layer;
the third metal layer is electrically connected with the grounding ends of the transmitting filter wafer and the receiving filter wafer.
Specifically, a first metal layer on the upper surface of the packaging substrate is transversely arranged between a transmitting filter wafer and a receiving filter wafer, and two end parts are respectively overlapped with the transmitting filter wafer and the receiving filter wafer; the overlapped parts at two ends of the first metal layer respectively form a first MIM capacitor and a second MIM capacitor with the resonators of the transmitting filter wafer and the resonators of the receiving filter wafer, and the first MIM capacitor and the second MIM capacitor are connected in series through the middle part of the first metal layer, so that the capacitors are integrated between the access points of the diplexer with the trapezoid structure, the coupling capacitance can be realized between the parallel resonators of the transmitting filter and the parallel resonators of the receiving filter without adding more layers of substrates or introducing discrete components, the out-of-band inhibition points of the transmitting filter and the receiving filter are changed, and the out-of-band inhibition points of the transmitting filter and the receiving filter are moved to required positions, so that the isolation degree of the diplexer is improved.
The second metal layer on the upper surface of the packaging substrate is longitudinally arranged between the transmitting filter wafer and the receiving filter wafer, and comprises two parts of metal layers which are respectively arranged on the upper side and the lower side of the first metal layer, so that the transmitting filter and the receiving filter of the duplexer can be separated, the input and the output of the transmitting filter and the receiving filter are separated from an ANT, the coupling between the transmitting filter and the receiving filter is reduced, and the isolation degree of the duplexer is further improved.
The plurality of third metal layers are arranged on the upper surface of the packaging substrate and are arranged outside the first metal layer and the second metal layer. The setting data of the third metal layer is determined according to the number of antenna ports, the sending ports, the receiving ports and the resonators, namely the sum of the number of the antenna ports, the number of the sending ports and the number of the parallel resonators in the wafer of the sending filter. Each third metal layer is connected to the lower surface metal layer of the packaging substrate through a through hole in the packaging substrate or a wire winding inductor for grounding.
In an alternative embodiment of the present invention, the transmit filter wafer of the present invention specifically includes:
a transmission filter having a ladder structure formed by a plurality of series resonators and parallel resonators; wherein each of the series resonators and the parallel resonators includes a substrate, and a bottom electrode and a top electrode disposed over the substrate.
Specifically, a transmission filter having a ladder structure is configured between an antenna port and a transmission port by a plurality of series resonators connected in series, and parallel resonators respectively connected in parallel between two adjacent series resonators. Each of the series resonators and the parallel resonators includes a substrate, and a bottom electrode, a piezoelectric layer, a top electrode, and a protective layer sequentially disposed over the substrate.
In the case of the transmission filter,
The antenna port is connected with the top electrode of the adjacent series resonator, the bottom electrode of the series resonator is connected with the bottom electrodes of the adjacent series resonator and the parallel resonator, and the top electrode of the adjacent series resonator is connected with the top electrodes of the adjacent series resonator and the parallel resonator;
Or the antenna port is connected to the bottom electrode of an adjacent series resonator, the top electrode of which is connected to the top electrodes of its adjacent series resonator and parallel resonator, and the bottom electrode of which is connected to the bottom electrodes of its adjacent series resonator and parallel resonator.
Specifically, as shown in fig. 2, the antenna port 1 is connected to the top electrode of the adjacent series resonator TS1 (as shown in the upper diagonal grid of fig. 2), the bottom electrode of the series resonator TS1 (as shown in the lower diagonal grid of fig. 2) is connected to the bottom electrode of the adjacent series resonator TS2 and the parallel resonator TP1, the top electrode of the parallel resonator TP1 is electrically connected to the corresponding third metal layer on the upper surface of the package substrate by a solder ball, the top electrode of the series resonator TS2 is connected to the top electrode of the adjacent series resonator TS3 and the top electrode of the parallel resonator TP2, the top electrode of the parallel resonator TP2 overlaps one end of the first metal layer on the upper surface of the package substrate to form a second MIM capacitor (as shown in the circle C2 of fig. 2), the bottom electrode of the parallel resonator TP2 is electrically connected to the corresponding third metal layer on the upper surface of the package substrate by a solder ball, the bottom electrode of the series resonator TS3 is electrically connected to the bottom electrode of the adjacent series resonator TS4 and the bottom electrode of the parallel resonator TP3 by a solder ball, and the top electrode of the parallel resonator TP3 is electrically connected to the corresponding third metal layer on the upper surface of the package substrate by a solder ball.
The receiving filter wafer of the present invention specifically comprises:
A reception filter having a ladder structure formed by a plurality of series resonators and parallel resonators; wherein each of the series resonators and the parallel resonators includes a substrate, and a bottom electrode and a top electrode disposed over the substrate.
Specifically, a reception filter having a ladder structure is configured between an antenna port and a transmission port by a plurality of series resonators connected in series, and parallel resonators respectively connected in parallel between two adjacent series resonators. Each of the series resonators and the parallel resonators includes a substrate, and a bottom electrode, a piezoelectric layer, a top electrode, and a protective layer sequentially disposed over the substrate.
In the case of a reception filter,
The antenna port is connected with the top electrode of the adjacent series resonator, the bottom electrode of the series resonator is connected with the bottom electrodes of the adjacent series resonator and the parallel resonator, and the top electrode of the adjacent series resonator is connected with the top electrodes of the adjacent series resonator and the parallel resonator;
Or the antenna port is connected to the bottom electrode of an adjacent series resonator, the top electrode of which is connected to the top electrodes of its adjacent series resonator and parallel resonator, and the bottom electrode of which is connected to the bottom electrodes of its adjacent series resonator and parallel resonator.
Specifically, as shown in fig. 2, the antenna port 1 is connected to the top electrode of the adjacent series resonator RS1 (as shown in the upper diagonal grid of fig. 2), the bottom electrode of the series resonator RS1 (as shown in the lower diagonal grid of fig. 2) is connected to the bottom electrode of the adjacent series resonator RS2 and the parallel resonator RP1, the top electrode of the parallel resonator RP1 is electrically connected to the corresponding third metal layer on the upper surface of the package substrate by a solder ball, the top electrode of the series resonator RS2 is connected to the top electrode of the adjacent series resonator RS3 and the top electrode of the parallel resonator RP2, the top electrode of the parallel resonator RP2 overlaps the other end of the first metal layer on the upper surface of the package substrate to form a first MIM capacitor (as shown in the circle C1 of fig. 2), the bottom electrode of the parallel resonator RP2 is electrically connected to the corresponding third metal layer on the upper surface of the package substrate by a solder ball, the bottom electrode of the series resonator RS3 is electrically connected to the bottom electrode of the adjacent series resonator RP4 and the bottom electrode of the parallel resonator RP3 by a solder ball, and the top electrode of the parallel resonator RP3 is electrically connected to the corresponding third metal layer on the top surface of the package substrate by a solder ball.
When the filters in series-parallel connection are arranged, the input port is connected with the top electrode of the adjacent series resonator, the bottom electrode of the series resonator is connected with the bottom electrodes of the adjacent series resonator and the parallel resonator, and the top electrode of the adjacent series resonator is connected with the top electrodes of the adjacent series resonator and the parallel resonator; or the input port is connected with the bottom electrode of the adjacent series resonator, the top electrode of the series resonator is connected with the top electrodes of the adjacent series resonator and the parallel resonator, the bottom electrode of the adjacent series resonator is connected with the bottom electrodes of the adjacent series resonator and the parallel resonator, the mode that all the adjacent resonators are directly connected with the bottom electrode on the same plane through the top electrode or all the adjacent resonators are realized, the mode that the top electrode is required to be connected with the bottom electrodes of other adjacent resonators (the top electrode and the bottom electrode are not on the same plane, the upper layer and the lower layer are separated by a non-conductive piezoelectric layer in the middle, if the top electrode and the bottom electrode are connected, the middle piezoelectric layer is required to be hollowed out, so that the piezoelectric layer is trapped in the hollowed-out area when the top electrode is deposited, and the piezoelectric layer is connected with the bottom electrode, at the moment, the connection between the electrodes is not on the same plane, the performance is damaged due to parasitic effect), meanwhile, the size of the device is further reduced, and the device is miniaturized is realized.
In an alternative embodiment of the present invention, between the transmit filter wafer and the receive filter wafer and the package, the top electrode or the bottom electrode of the parallel resonator in the transmit filter wafer and the receive filter wafer is electrically connected to the third metal layer on the upper surface of the package substrate through solder balls.
And the third metal layer on the upper surface of the package substrate is connected to the lower surface metal layer of the package substrate through a via hole or a wire winding inductance in the package substrate.
According to the invention, the transmitting filter wafer and the receiving filter wafer are directly welded on the upper surface of the packaging substrate in a flip-chip manner through the solder balls, so that metal through holes on the packaging wafer are removed, and the device loss is optimized.
The performance curves of the examples and comparative examples are shown in fig. 3. The dashed line is the performance curve of the example and the solid line is the performance curve of the comparative example. The embodiment realizes the coupling capacitance between the parallel resonator of the transmitting filter and the parallel resonator of the receiving filter by forming the MIM capacitance between the resonator top electrode and the packaging substrate and adjusting the sizes and positions of the MIM capacitances C1 and C2 without adding more layers of substrates and introducing discrete components, changes the out-of-band rejection points of the transmitting filter and the receiving filter, and moves the out-of-band rejection points to the required positions so as to improve the isolation degree of the duplexer. In this embodiment, the capacitors C1 and C2 are respectively connected to the remote end of the second parallel branch RP2 of the receiving filter and the remote end of the first parallel branch TP 1 of the transmitting filter, so as to move the out-of-band rejection points of the TX filter and the RX filter to appropriate positions, thereby improving the isolation of the diplexer. As can be seen from simulation results, the RX-to-TX isolation of the duplexer is improved slightly, and the TX-to-RX isolation is improved obviously from 1.74GHz to 1.77GHz, namely about 3dB at maximum.
The principles and embodiments of the present invention have been described in detail with reference to specific examples, which are provided to facilitate understanding of the method and core ideas of the present invention; meanwhile, as those skilled in the art will have variations in the specific embodiments and application scope in accordance with the ideas of the present invention, the present description should not be construed as limiting the present invention in view of the above.
Those of ordinary skill in the art will recognize that the embodiments described herein are for the purpose of aiding the reader in understanding the principles of the present invention and should be understood that the scope of the invention is not limited to such specific statements and embodiments. Those of ordinary skill in the art can make various other specific modifications and combinations from the teachings of the present disclosure without departing from the spirit thereof, and such modifications and combinations remain within the scope of the present disclosure.