FBAR and IPD fused broadband sharp double-sideband filter circuit and chip

Abstract

The invention discloses an FBAR and IPD fused broadband sharp double-sideband filter circuit and a chip, and relates to a filter and a packaging structure based on a film bulk acoustic resonator and an integrated passive device, the filter comprises a first signal transmission end, a second signal transmission end and a filter network; the filter network comprises N first resonance units composed of film bulk acoustic resonators, M second resonance units composed of inductors and capacitors, Q third resonance units composed of film bulk acoustic resonators and inductors connected in series, and at least one fourth resonance unit composed of inductors and capacitors. Wherein N, M and Q are all natural numbers greater than or equal to 2, and the resonant frequency of the film bulk acoustic resonator in at least one third resonance unit is different from the resonant frequency of the film bulk acoustic resonators in other third resonance units; the first resonance unit and the second resonance unit are arranged on a series branch between the first signal transmission end and the second signal transmission end, and the third resonance unit and the fourth resonance unit are arranged between a parallel branch and the ground.

Description

Technical Field

[0001] The present disclosure relates to a filter and a chip, and more specifically, to a FBAR and IPD fused broadband sharp double-sideband filter circuit and chip. Background Art

[0002] Film Bulk Acoustic Resonator (FBAR) is a radio frequency device that uses a thin film layer of piezoelectric material to achieve acoustic resonance. FBAR technology plays a vital role in RF filter design, especially in mobile communications, satellite communications and radar systems, because they provide high frequency selectivity, high Q value, small size and low power consumption.

[0003] Although FBAR technology performs well in many RF applications, when designing large-bandwidth devices, since the bandwidth of the filter constructed with thin film bulk acoustic wave resonators is small and the Q value is easily deteriorated in higher frequency bands, if thin film bulk acoustic wave resonators are used to implement large-bandwidth devices, a large amount of loss and suppression and other performance must be sacrificed during the design to meet the in-band matching.

[0004] The existing IPD (Intergrated Passive Devices) technology uses an LC filter composed of inductors and capacitors to achieve a large bandwidth. However, due to process limitations, the Q value of the inductors and capacitors achieved by the IPD process is not high. The low Q value will increase the loss of the components and cause the insertion loss of the LC filter to deteriorate. Therefore, it is necessary to limit the number of devices in the design to reduce the overall energy loss, and the limitation on the number of devices will limit the controllability of the filter performance. In general, traditional IPD filters usually cannot take into account both roll-off and low insertion loss.

[0005] The prior art also attempts to build a hybrid filter by combining the advantages of LC devices and FBAR devices. Figure 1 FIG. 2 shows a schematic diagram of the structure of a hybrid filter in the prior art. Figure 1 As shown, the filter includes a first signal transmission terminal 100 , a second signal transmission terminal 200 , three series branches between the first signal transmission terminal 100 and the second signal transmission terminal 200 , and three parallel branches.

[0006] The first series branch in the series branch is composed of a first LC resonance unit, the second series branch is composed of a first FBAR resonance unit, and the third series branch is composed of a second FBAR resonance unit. The first LC resonance unit includes a capacitor C1 and an inductor L1 connected in series, and an inductor L6 connected in parallel with the capacitor C1 and the inductor L1 connected in series. The first FBAR resonance unit and the second FBAR resonance unit are both composed of a single thin film bulk acoustic resonator.

[0007] The first parallel branch in the parallel branch is arranged between the first signal transmission terminal 100 and the ground, and the first parallel branch is composed of a second LC resonance unit. The second parallel branch is arranged between the node between the first series branch and the second series branch and the ground, and the second parallel branch is composed of a third LC resonance unit. The third parallel branch is arranged between the second signal transmission terminal 200 and the ground. The third parallel branch is composed of a fourth LC resonance unit. The second LC resonance unit includes a parallel inductor L3 and a capacitor C3, and then the parallel inductor L3 and the capacitor C3 are connected in series with the inductor L2 and the capacitor C2; the third LC resonance unit includes a parallel inductor L4 and a capacitor C4; the fourth LC resonance unit includes a parallel inductor L5 and a capacitor C5.

[0008] Please refer to Figure 2 , Figure 2 Show Figure 1 The performance curve of the hybrid filter is shown in FIG. 1 , where curve 1 represents the S11 curve of the hybrid filter, and curve 2 represents the S21 curve of the hybrid filter. Figure 2 It can be seen that the use of Figure 1 When the hybrid filter architecture is shown, the flatness in the filter band is poor, the bandwidth is narrow, and the suppression is poor. Therefore, it is expected in the industry to develop a filter with high performance to simultaneously meet the requirements of extended bandwidth and high suppression. Summary of the invention

[0009] The present disclosure carefully designs the circuit structure by using a thin film bulk acoustic wave resonator and an integrated passive hybrid filter, develops a high-performance filter that can achieve a large bandwidth while taking into account roll-off and low insertion loss, and provides a packaging structure including the filter.

[0010] A brief overview of the disclosure will be given below in order to provide a basic understanding of certain aspects of the disclosure. It should be understood that this overview is not an exhaustive overview of the disclosure. It is not intended to identify key or important parts of the disclosure, nor is it intended to limit the scope of the disclosure. Its purpose is simply to give certain concepts in a simplified form as a prelude to a more detailed description discussed later.

[0011] According to one aspect of the present disclosure, a filter circuit is provided, comprising: a first signal transmission end, a second signal transmission end and a filtering network between the first signal transmission end and the second signal transmission end; the filtering network comprises N first resonance units consisting of thin film bulk acoustic wave resonators, M second resonance units consisting of inductors and capacitors, Q third resonance units consisting of thin film bulk acoustic wave resonators and serially connected inductors, and at least one fourth resonance unit consisting of inductors and capacitors, wherein N, M and Q are all natural numbers greater than or equal to 2, and the resonance frequency of the thin film bulk acoustic wave resonator in at least one third resonance unit is different from the resonance frequency of the thin film bulk acoustic wave resonators in other third resonance units; the first resonance unit and the second resonance unit are arranged on a series branch between the first signal transmission end and the second signal transmission end, and the third resonance unit and the fourth resonance unit are arranged between a parallel branch and a ground, wherein the first resonance unit provides an upper sideband for the filter, the second resonance unit provides a pole support for the bandwidth of the filter, the third resonance unit provides a lower sideband for the filter, the serially connected inductor in the third resonance unit provides a high-frequency far stopband zero point of the filter, and the fourth resonance unit provides a low-frequency far stopband zero point and an in-band pole of the filter.

[0012] Furthermore, the plurality of first resonant units arranged in the series branch are not isolated by the second resonant unit, and each third resonant unit is respectively connected to a connection node in the series branch formed by the plurality of first resonant units.

[0013] Furthermore, the resonance frequency of at least one film bulk acoustic wave resonator in the third resonance unit of the first parallel branch is lower than the resonance frequency of the film bulk acoustic wave resonator in the other third resonance units.

[0014] Further, the filtering network includes a first series branch, a second series branch, a third series branch and a fourth series branch connected in sequence, a first node is provided between the first series branch and the second series branch, a second node is provided between the second series branch and the third series branch, a third node is provided between the third series branch and the fourth series branch, the first parallel branch is arranged between the first node and the ground, the second parallel branch is arranged between the second node and the ground, the third parallel branch is arranged between the third node and the ground, the first series branch and the fourth series branch include a second resonance unit, the second series branch and the third series branch include a first resonance unit, the first parallel branch and the third parallel branch include a third resonance unit, and the second parallel branch includes a fourth resonance unit.

[0015] Furthermore, the second resonant unit in the first series branch is composed of a capacitor C 3_1 and inductor L 3_1The first resonance unit in the second series branch is composed of four film bulk acoustic wave resonators connected in series, the first resonance unit in the third series branch is composed of three film bulk acoustic wave resonators connected in series, and the second resonance unit in the fourth series branch is composed of an inductor L 3_2 and capacitor C 3_2 The third resonant unit in the first parallel branch is composed of three thin film bulk acoustic resonators and a capacitive inductor L 1_1 The capacitor C in the fourth resonant unit of the second parallel branch is in series. 2_1 and inductor L 2_1 Then connect in series with capacitor C 2_2 The third resonance unit of the third parallel branch consists of three film bulk acoustic resonators and a capacitive inductor L 1_2 Series structure.

[0016] Furthermore, the resonance frequency of the film bulk acoustic wave resonator in the first parallel branch is 107 MHz±20 MHz less than the resonance frequency of the film bulk acoustic wave resonator in the third parallel branch.

[0017] According to another aspect of the present disclosure, a filter chip is provided, the filter comprising the filter circuit structure of any of the aforementioned items; a packaging substrate, the packaging substrate comprising a plurality of metal layers, each metal layer being separated by a dielectric layer; the thin film bulk acoustic wave resonators in the first resonance unit and the third resonance unit in the filter circuit structure are arranged on a first chip, and the first chip is mounted face-up or flip-chip on the packaging substrate; the capacitors and inductors in the second resonance unit and the fourth resonance unit are arranged on a second chip through an integrated passive device (IPD) process, and the second chip is mounted face-up or flip-chip on the packaging substrate.

[0018] Further, the inductor in the second resonance unit and the inductor in the third resonance unit each include a first part formed by a spiral inductor and a second part formed by a corresponding trace on the package substrate.

[0019] Furthermore, the inductors with small inductance in the second resonance unit and the third resonance unit are formed by corresponding traces on the package substrate.

[0020] Furthermore, the area of ​​a single film bulk acoustic wave resonator in the third resonance unit on the first chip is greater than or equal to the area of ​​a single film bulk acoustic wave resonator in the first resonance unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The specific contents of the present disclosure are described below with reference to the accompanying drawings, which will help to more easily understand the above and other purposes, features and advantages of the present disclosure. The accompanying drawings are only for illustrating the principles of the present disclosure. The sizes and relative positions of the units in the accompanying drawings need not be drawn to scale.

[0022] Figure 1A schematic diagram showing the structure of a hybrid filter in the prior art is shown;

[0023] Figure 2 Show Figure 1 Performance curve of the hybrid filter shown;

[0024] Figure 3 A circuit structure block diagram of a filter in an embodiment of the present disclosure is shown;

[0025] Figure 4 A specific embodiment of the filter circuit structure in the embodiment of the present disclosure is shown;

[0026] Figure 5 Show Figure 4 The filter circuit structure shown has high-frequency and low-frequency matching within the balanced passband;

[0027] Figure 6a-6b Show Figure 4 The matching and suppression curve relationship of the filter circuit structure shown;

[0028] Figure 7a A schematic diagram of a three-dimensional structure of a package of the filter circuit structure disclosed in the present invention is shown;

[0029] Figure 7b A top view of a package of the filter circuit structure disclosed in the present invention is shown;

[0030] Figure 8 A wiring diagram showing the inductor with a smaller inductance value in the second resonant unit and the third resonant unit;

[0031] Fig. 9 The performance EM simulation curve of the filter circuit structure in the present disclosure is shown;

[0032] Fig.10 The filter circuit structure and Figure 1 Performance curve comparison of filter circuit structures in Fig. DETAILED DESCRIPTION

[0033] Below, exemplary disclosures of the present disclosure will be described in conjunction with the accompanying drawings. For the sake of clarity and conciseness, not all features of implementing the present disclosure are described in the specification. However, it should be understood that many decisions specific to the present disclosure may be made in the process of developing any such implementation of the present disclosure in order to achieve the developer's specific goals, and these decisions may vary from one disclosure to another.

[0034] It should also be noted that, in order to avoid obscuring the present disclosure due to unnecessary details, only device structures closely related to the solutions according to the present disclosure are shown in the drawings, while other details that are not closely related to the present disclosure are omitted.

[0035] It should be understood that the present disclosure is not limited to the described embodiments due to the following description with reference to the accompanying drawings. In the present disclosure, features between different embodiments may be replaced or borrowed, and one or more features may be omitted in one embodiment, if feasible.

[0036] See also Figure 3 , Figure 3 A circuit structure block diagram of a filter in an embodiment of the present disclosure is shown.

[0037] The filter includes a first signal transmission end 100, a second signal transmission end 200, and a filter network 300 between the first signal transmission end 100 and the second signal transmission end 200. The filter network 300 includes N first resonance units consisting of thin film bulk acoustic wave resonators, M second resonance units consisting of integrated passive devices, Q third resonance units consisting of thin film bulk acoustic wave resonators and inductors, and a fourth resonance unit 304 consisting of inductors and capacitors. The N first resonance units and the M second resonance units are connected in series, and the Q third resonance units are each connected in parallel between a node between the first resonance unit and the second resonance unit and ground, wherein N, M and Q are all natural numbers greater than or equal to 2. The resonance frequency of the thin film bulk acoustic wave resonator in at least one third resonance unit is different from the resonance frequency of the thin film bulk acoustic wave resonator in other third resonance units to provide a near stopband zero point.

[0038] The first resonance unit includes at least one thin film bulk acoustic wave resonator. Preferably, the first resonance unit can be composed of one thin film bulk acoustic wave resonator or a plurality of thin film bulk acoustic wave resonators in series, parallel or series-parallel form. Figure 3 As shown in , the first resonance unit may specifically be a first device group 3011, a second device group 3012, etc., and each device group of the first resonance unit may include the same or different components.

[0039] The passive lumped components in the second resonant unit may be capacitors, inductors, etc. Further, the second resonant unit may be composed of a plurality of passive lumped components connected in series, in parallel, or in series and in parallel. Figure 3 As shown in , the second resonance unit may specifically be a third device group 3021 , a fourth device group 3022 , etc., and each device group of the second resonance unit may include the same or different components.

[0040] The third resonance unit includes at least one FBAR and an inductor. When there are multiple FBARs in the third resonance unit, they can be connected in series, in parallel, or in series-parallel. The third resonance unit uses the capacitance of the FBAR and the inductor to form resonance. Figure 3As shown, the third resonance unit may specifically be a fifth device group 3031, a sixth device group 3032, etc., and each device group of the third resonance unit may include the same or different components.

[0041] In the circuit structure of the filter provided by the present invention, the first resonance unit provides a highly selective upper sideband for the filter, the second resonance unit provides pole support for the large bandwidth of the filter, the third resonance unit provides a highly selective lower sideband for the filter, and the capacitive inductor connected in series in the third resonance unit provides a high-frequency far-out-band zero point of the filter. The high-frequency far-out-band (High Frequency Far Out-of-Band) generally refers to a high frequency band in the filter circuit, far away from the working frequency band or passband, and a frequency range in which the signal is significantly suppressed or attenuated.

[0042] It should be noted that a plurality of first resonant units 301 and a plurality of second resonant units 302 are arranged in a series branch, and a plurality of third resonant units 303 are respectively arranged between a parallel branch and the ground. The plurality of first resonant units 301 arranged in the series branch are not isolated by the second resonant units 302 arranged in the series branch, and each third resonant unit 303 is respectively connected to a connection node in the series branch formed by the plurality of first resonant units 301, so as to facilitate the preparation of the filter chip.

[0043] Furthermore, a fourth resonance unit composed of an inductor and a capacitor may be provided between the plurality of first resonance units 301. The fourth resonance unit is arranged between the connection node between the plurality of first resonance units 301 and the ground. The fourth resonance unit provides a low frequency far out-of-band zero point and an in-band pole of the filter. The low frequency far out-of-band refers to a low frequency band far away from the working frequency band or the passband in the filter circuit, and a frequency range in which the signal is significantly suppressed or attenuated.

[0044] See also Figure 4 , Figure 4 A specific embodiment of the filter circuit structure in the embodiment of the present disclosure is shown.

[0045] The filter includes a first signal transmission end 100, a second signal transmission end 200, and a filter network 300 between the first signal transmission end 100 and the second signal transmission end 200. The filter network 300 includes a first series branch NS1, a second series branch NS2, a third series branch NS3, and a fourth series branch NS4 connected in sequence, a first node is provided between the first series branch NS1 and the second series branch NS2, a second node is provided between the second series branch NS2 and the third series branch NS3, and a third node is provided between the third series branch NS3 and the fourth series branch NS4. The first parallel branch NP1 is provided between the first node and the ground, the second parallel branch NP2 is provided between the second node and the ground, the third parallel branch NP3 is provided between the third node and the ground, the first series branch NS1 and the fourth series branch NS4 include a second resonance unit, the second series branch NS2 and the third series branch NS3 include a first resonator network, the first parallel branch NP1 and the third parallel branch NP3 include a third resonance unit, and the second parallel branch NP2 includes a fourth resonance unit.

[0046] The second resonant unit in the first series branch NS1 is composed of a capacitor C 3_1 and inductor L 3_1 The first resonator network in the second series branch NS2 is composed of a thin film bulk acoustic wave resonator S 1_1 , Thin Film Bulk Acoustic Wave Resonator S 1_2 , Thin Film Bulk Acoustic Wave Resonator S 1_3 and FBAW 1_4 The first resonator network in the third series branch NS3 is composed of a thin film bulk acoustic resonator S 2_1 , Thin Film Bulk Acoustic Wave Resonator S 2_2 , Thin Film Bulk Acoustic Wave Resonator S 2_3 The second resonant unit in the fourth series branch NS4 is composed of an inductor L 3_2 and capacitor C 3_2 The thin film bulk acoustic wave resonator S in the second series branch NS2 1_1 , Thin Film Bulk Acoustic Wave Resonator S 1_2 , Thin Film Bulk Acoustic Wave Resonator S 1_3 and FBAW 1_4 The resonant frequency is set to be the same as that of the film bulk acoustic wave resonator S in the third series branch NS3. 2_1 , Thin Film Bulk Acoustic Wave Resonator S 2_2 , Thin Film Bulk Acoustic Wave Resonator S 2_3 The resonant frequency is the same.

[0047] The first parallel branch NP1 is set between the first node and the ground, the second parallel branch NP2 is set between the second node and the ground, and the third parallel branch NP3 is set between the third node and the ground. The third resonance unit in the first parallel branch NP1 is composed of a thin film bulk acoustic resonator P 1_1 , Film Bulk Acoustic Wave Resonator P 1_2 , Film Bulk Acoustic Wave Resonator P 1_3 and capacitive inductance L 1_1 The capacitor C in the third resonant unit of the second parallel branch NP2 is connected in series. 2_1 and inductor L 2_1 Then connect in series with capacitor C 2_2 The third resonance unit of the third parallel branch NP3 is composed of a thin film bulk acoustic wave resonator P 2_1 , Film Bulk Acoustic Wave Resonator P 2_2 , Film Bulk Acoustic Wave Resonator P 2_3 and capacitive inductance L 1_2 The thin film bulk acoustic wave resonator P of the third resonance unit in the first parallel branch NP1 is connected in series. 1_1 , Film Bulk Acoustic Wave Resonator P 1_2 , Film Bulk Acoustic Wave Resonator P 1_3 The resonant frequency of the film bulk acoustic wave resonator P in the third parallel branch 2_1 , Film Bulk Acoustic Wave Resonator P 2_2 , Film Bulk Acoustic Wave Resonator P 2_3 The resonant frequencies of the thin film bulk acoustic wave resonator P in the third resonant unit are different. 1_1 , Film Bulk Acoustic Wave Resonator P 1_2 , Film Bulk Acoustic Wave Resonator P 1_3 The resonant frequency of the film bulk acoustic wave resonator P in the third parallel branch NP3 is 2_1 , Film Bulk Acoustic Wave Resonator P 2_2 , Film Bulk Acoustic Wave Resonator P 2_3 The resonant frequency of the FBAR in the first parallel branch NP1 is set to be smaller than the resonant frequency of the FBAR in the third parallel branch NP3, which can be used to provide a near stopband zero.

[0048] Figure 4 In the filter circuit structure, the inductor L in the fourth series branch NS4 3_2 and capacitor C 3_2 It is used to adjust the matching distribution of the upper and lower parts of the filter passband. The capacitor C in the second parallel branch 2_1 and inductor L 2_1 The series connection is grounded to provide a low-frequency zero point. The second parallel branch is connected through an additional capacitor C 2_2Grounding can provide a pole at the zero high frequency. It should be noted that the capacitor C in the second parallel branch should be adjusted. 2_1 and inductor L 2_1 Changing the zero resonance will also affect the pole frequency.

[0049] See also Figure 5 , Figure 5 Show Figure 4 The filter circuit structure shown has a balanced passband with high and low frequency matching. Figure 5 It can be seen that when the matching in the filter passband is unbalanced due to coupling or other reasons, for example, the high-frequency matching in the passband is better than the low-frequency matching in the passband, then the high-frequency and low-frequency matching in the passband can be balanced by the above-mentioned inductor and capacitor elements in the integrated passive device of the filter network.

[0050] Figure 4 In the filter circuit structure, the inductor L in the first series branch NS1 3_1 and capacitor C 3_1 Used to adjust the balance between overall matching and suppression, increase the capacitance C 3_1 and inductor L 3_1 It will sacrifice matching and insertion loss to optimize stopband suppression, and vice versa, it will reduce suppression to optimize matching and insertion loss. Figure 6a-6b , Figure 6a-6b Show Figure 4 The matching and suppression curve relationship of the filter circuit structure is shown in FIG. Figure 6a As shown, increasing the capacitance C 3_1 and inductor L 3_1 Sacrifices matching and insertion loss, but optimizes stopband suppression, such as Figure 6b As shown, reduce the capacitance C 3_1 and inductor L 3_1 This reduces suppression but optimizes matching and insertion loss.

[0051] In the present disclosure, an LC resonator composed of an integrated multi-degree-of-freedom inductor and capacitor is introduced into a filter including a thin film bulk acoustic wave resonator, and the capacitor and inductor are designed to provide the filter with an in-band pole to support the bandwidth and in-band matching. At the same time, the LC resonator can introduce a zero point by adding an external capacitor, grounding the inductor, etc., to further deepen the out-of-band suppression. The thin film bulk acoustic wave resonator network in the filter can be used to optimize the suppression and loss of the filter based on the characteristics of high Q value. Therefore, the present disclosure provides a high-performance filter that can meet the requirements of bandwidth extension and suppression at the same time.

[0052] See also Figure 7a-Figure 7b , Figure 7a A schematic diagram of a three-dimensional structure of a package of the filter circuit structure disclosed in the present invention is shown; Figure 7b FIG. 1 shows a top view of a package of the filter circuit structure disclosed in the present invention. Figure 7aAs shown, Figure 4 The first resonance unit and the thin film bulk acoustic wave resonator in the third resonance unit are arranged on the first chip 2000. The area of ​​a single thin film bulk acoustic wave resonator in the third resonance unit is greater than or equal to the area of ​​a single thin film bulk acoustic wave resonator in the first resonance unit. Figure 4 As shown, the area of ​​a single film bulk acoustic resonator in the second series branch NS2 is larger than the area of ​​a single film bulk acoustic resonator in the third series branch NS3; the area of ​​a single film bulk acoustic resonator in the first parallel branch NP1 is larger than the area of ​​a single film bulk acoustic resonator in the third parallel branch.

[0053] The capacitors and inductors in the second resonant unit and the fourth resonant unit can be formed on the second chip 3000 by IPD process. It can be understood that the capacitors can also be in the form of chip capacitors 3100. The package substrate 1000 includes multiple metal layers, and the metal layers are separated by dielectric layers. The first chip 2000 and the second chip 3000 can be mounted on the package substrate 1000 in the upright or inverted manner. Figure 7a-Figure 7b As shown in , the solder joints on the first chip 2000 are flipped and buckled on the corresponding solder joints on the package substrate 1000, that is, the first chip 2000 is flipped on the package substrate 1000. It can be understood that since the traces on the package substrate 1000 can be equivalent to inductors, the inductors in the second resonant unit and the inductors in the third resonant unit can each include a first part composed of the spiral inductor 3200 and a second part composed of the corresponding traces on the package substrate 1000. The inductance value of each inductor is the sum of the inductance value of the spiral inductor 3200 and the equivalent inductance value of the corresponding traces on the package substrate 1000.

[0054] It can be understood that in order to ensure that the filter achieves a small size at the chip level and to reduce the routing density of the spiral inductor 3200 to reduce inductive coupling, the inductors with smaller inductances in the second resonant unit and the third resonant unit can also be completely implemented based on the routing on the packaging substrate 1000.

[0055] See also Figure 8 , Figure 8 FIG. 4 shows the wiring diagram of the inductor with smaller inductance in the second resonant unit and the third resonant unit. Figure 8 As shown, the inductance L on the first parallel branch NP1 of the filter circuit structure in the present disclosure is 11 It is completely implemented based on the routing 3300 on the packaging substrate 1000 .

[0056] See also Fig. 9 , Fig. 9 The performance EM simulation curve of the filter circuit structure in the present disclosure is shown. Fig. 9 It can be seen that the present disclosure Figure 4The filter circuit structure shown in the figure can realize the N79 full-band filter, and the bandwidth of the filter can reach 600MHz. The insertion loss in the passband is better than 2dB, the high-frequency suppression is better than 40dB, and the double-side band has FBAR type high roll-off.

[0057] See also Fig.10 , Fig.10 The filter circuit structure and Figure 1 The performance curve comparison diagram of the filter circuit structure in FIG. 3 is the S21 curve of the filter disclosed in the present invention, and curve 4 is Figure 1 The S21 curve of the filter in the middle shows that, compared with the hybrid filter in the prior art, the filter using the circuit structure disclosed in the present invention has very sharp double-sideband selectivity, and the bandwidth of the filter is also increased, while the suppression is strengthened.

[0058] In summary, the filter circuit structure provided by the present invention can combine the advantages of filters built by passive lumped devices and filters built by bulk acoustic wave resonators, enhance suppression while achieving a large bandwidth, and provide a small size at the chip level, thereby adapting well to the trend of device miniaturization.

[0059] The filter of the embodiment of the present disclosure can be widely used in electronic devices, and exemplary communication devices are mobile phones, personal digital assistants, electronic game devices, wearable terminals, etc.

[0060] The present disclosure is described above in conjunction with specific implementation schemes, but it should be clear to those skilled in the art that these descriptions are exemplary and are not intended to limit the scope of protection of the present disclosure. Those skilled in the art can make various variations and modifications to the present disclosure based on the spirit and principles of the present disclosure, and these variations and modifications are also within the scope of the present disclosure.

Claims

1. A filter circuit, characterized in that: include: A first signal transmission end, a second signal transmission end, and a filtering network between the first signal transmission end and the second signal transmission end; The filter network includes N first resonance units consisting of film bulk acoustic wave resonators, M second resonance units consisting of inductors and capacitors, Q third resonance units consisting of film bulk acoustic wave resonators and serially connected inductors, and at least one fourth resonance unit consisting of inductors and capacitors, wherein N, M and Q are all natural numbers greater than or equal to 2, and the resonance frequency of the film bulk acoustic wave resonator in at least one third resonance unit is different from the resonance frequency of the film bulk acoustic wave resonators in other third resonance units; The first resonance unit and the second resonance unit are arranged on a series branch between the first signal transmission end and the second signal transmission end, and the third resonance unit and the fourth resonance unit are arranged between the parallel branch and the ground, wherein the first resonance unit provides an upper sideband for the filter, the second resonance unit provides a pole support for the bandwidth of the filter, the third resonance unit provides a lower sideband for the filter, the inductor connected in series in the third resonance unit provides a high-frequency far-stopband zero point of the filter, and the fourth resonance unit provides a low-frequency far-stopband zero point and an in-band pole of the filter.

2. The filter circuit according to claim 1, characterized in that: The plurality of first resonant units arranged in the series branch are not isolated by the second resonant unit, and each third resonant unit is respectively connected to a connection node in the series branch formed by the plurality of first resonant units.

3. The filter circuit according to claim 1, wherein: The resonance frequency of at least one film bulk acoustic wave resonator in the third resonance unit of the first parallel branch is lower than the resonance frequency of the film bulk acoustic wave resonator in the other third resonance units.

4. The filter circuit according to claim 3, characterized in that: The filtering network includes a first series branch, a second series branch, a third series branch and a fourth series branch connected in sequence, a first node is provided between the first series branch and the second series branch, a second node is provided between the second series branch and the third series branch, a third node is provided between the third series branch and the fourth series branch, the first parallel branch is arranged between the first node and the ground, the second parallel branch is arranged between the second node and the ground, the third parallel branch is arranged between the third node and the ground, the first series branch and the fourth series branch include a second resonance unit, the second series branch and the third series branch include a first resonance unit, the first parallel branch and the third parallel branch include a third resonance unit, and the second parallel branch includes a fourth resonance unit.

5. The filter circuit according to claim 4, characterized in that: The second resonant unit in the first series branch is composed of a capacitor C 3_1 and inductor L 3_1 The first resonance unit in the second series branch is composed of four film bulk acoustic wave resonators connected in series, the first resonance unit in the third series branch is composed of three film bulk acoustic wave resonators connected in series, and the second resonance unit in the fourth series branch is composed of an inductor L 3_2 and capacitor C 3_2 The third resonant unit in the first parallel branch is composed of three thin film bulk acoustic resonators and a capacitive inductor L 1_1 The capacitor C in the fourth resonant unit of the second parallel branch is in series. 2_1 and inductor L 2_1 Then connect in series with capacitor C 2_2 The third resonance unit of the third parallel branch consists of three film bulk acoustic resonators and a capacitive inductor L 1_2 Series structure.

6. The filter circuit according to claim 5, characterized in that: The resonant frequency of the film bulk acoustic wave resonator in the first parallel branch is 107 MHz±20 MHz less than the resonant frequency of the film bulk acoustic wave resonator in the third parallel branch.

7. A filter chip, characterized in that: include: The filter comprises a filter circuit structure as described in any one of claims 1 to 6; A packaging substrate, the packaging substrate comprising multiple metal layers, each metal layer being separated by a dielectric layer; The thin film bulk acoustic wave resonators in the first resonance unit and the third resonance unit in the filter circuit structure are arranged on the first chip, and the first chip is mounted face-up or flip-down on the packaging substrate; The capacitors and inductors in the second resonance unit and the fourth resonance unit are arranged on the second chip through an integrated passive device (IPD) process, and the second chip is mounted face-up or flip-down on the packaging substrate.

8. The chip according to claim 7, characterized in that: The inductor in the second resonance unit and the inductor in the third resonance unit each include a first portion formed by a spiral inductor and a second portion formed by a corresponding trace on the package substrate.

9. The chip according to claim 7, characterized in that: The inductors with small inductance in the second resonant unit and the third resonant unit are formed by corresponding traces on the package substrate.

10. The chip according to any one of claims 7 to 9, characterized in that: The area of ​​a single film bulk acoustic wave resonator in the third resonance unit on the first chip is greater than or equal to the area of ​​a single film bulk acoustic wave resonator in the first resonance unit.

Images