Hybrid radio frequency filter

Abstract

A hybrid radio frequency filter comprises a first transceiving end, a second transceiving end, a first series capacitor, a second series capacitor, a first series resonator and a second series resonator. The first series capacitor, the first series resonator, the second series resonator and the second series capacitor are sequentially coupled between the first transceiving end and the second transceiving end in series.

Description

Technical Field

[0001] This invention relates to a hybrid radio frequency filter, and more particularly to a hybrid radio frequency filter comprising a series capacitor and a series resonator. Background Technology

[0002] With the development of communication technology, mobile phones, wireless communication devices, and other products support more and more frequency bands to increase signal coverage and international roaming capabilities. As wireless devices rapidly become more widespread, the demand for small and lightweight resonators and filters continues to increase.

[0003] Acoustic wave devices, such as surface acoustic wave (SAW) devices and bulk acoustic wave (BAW) devices, are widely used for the conversion and transmission of electrical and acoustic signals. Acoustic wave devices have numerous applications. For example, they can be used as filters to remove noise and retain wireless signals in specific frequency bands. They are characterized by low transmission loss, excellent electromagnetic interference resistance, and small size, making them widely used in various communication products. Furthermore, acoustic wave devices can also be used in resonators, transformers, and sensors.

[0004] For example, an RF filter may include series and parallel resonators to form a ladder-type filter. A film bulk acoustic resonator (FBAR) can be used to achieve better characteristics, such as quality factor, at high frequencies. Furthermore, for example, in some Wi-Fi applications, it may be necessary for the RF filter to have better characteristics over a wider frequency band (e.g., 5.945 GHz–7.125 GHz), but using only series or parallel FBARs in the circuit may not meet these requirements. Therefore, a hybrid RF filter is needed to achieve better characteristics at both higher frequencies and over a wider bandwidth. Summary of the Invention

[0005] One embodiment of the present invention provides a hybrid radio frequency filter. The hybrid radio frequency filter may include a first transceiver terminal, a second transceiver terminal, a first series capacitor, a second series capacitor, a first series resonator, and a second series resonator. The first series capacitor, the first series resonator, the second series resonator, and the second series capacitor may be sequentially connected in series between the first transceiver terminal and the second transceiver terminal. Attached Figure Description

[0006] Figure 1 This is a circuit diagram of a hybrid radio frequency filter according to an embodiment of the present invention.

[0007] Figure 2 This is a circuit diagram of a hybrid radio frequency filter according to another embodiment of the present invention.

[0008] Symbol explanation:

[0009] 10, 20: Hybrid RF Filters

[0010] TR1~TR2: Transmitter / Receiver

[0011] 12, 22: First matching circuit

[0012] 14, 24: Second matching circuit

[0013] CS1~CS4: Series capacitors

[0014] RP1~RP3: Parallel resonators

[0015] N1~N5: Nodes

[0016] RS1~RS2: Series resonator

[0017] CP1~CP3: Parallel capacitors

[0018] L1: Axis Detailed Implementation

[0019] The present invention can be understood by referring to the following detailed description in conjunction with the accompanying drawings. It should be noted that, for ease of understanding and for the sake of brevity, the drawings depict only a portion of the electronic device, and specific elements in the drawings are not drawn to scale. Furthermore, the number and dimensions of the elements in the drawings are for illustrative purposes only and are not intended to limit the scope of the invention. Elements indicated by the same symbols in the drawings have the same or similar properties or functions in the context.

[0020] It should be understood that the following embodiments can be modified by replacing, recombining, or mixing features from several different embodiments to complete other embodiments without departing from the spirit of the invention. Features between embodiments can be used individually or in combination as long as they do not violate the spirit of the invention or conflict with it. In the following description and claims, words such as "comprising," "containing," and "having" are open-ended terms and should therefore be interpreted as "containing but not limited to...". Therefore, when the terms "comprising," "containing," and / or "having" are used in the description of the present invention, they specify the presence of corresponding features, areas, steps, operations, and / or components, but do not exclude the presence of one or more corresponding features, areas, steps, operations, and / or components.

[0021] Figure 1This is a circuit diagram of a hybrid radio frequency filter 10 according to an embodiment of the present invention. As shown in the figure, in some embodiments, the hybrid radio frequency filter 10 may include a first transceiver terminal TR1 and a second transceiver terminal TR2. The first transceiver terminal TR1 can be used to receive an input radio frequency signal, and the second transceiver terminal TR2 can be used to transmit an output radio frequency signal. The radio frequency signal is transmitted from the first transceiver terminal TR1 to the second transceiver terminal TR2 and filtered by the hybrid radio frequency filter 10, leaving a radio frequency signal in a specific frequency band. However, the present invention is not limited thereto. In other embodiments, the second transceiver terminal TR2 can be used to receive an input radio frequency signal, and the first transceiver terminal TR1 can be used to transmit an output radio frequency signal. Furthermore, the hybrid radio frequency filter 10 may include a series path and a parallel path coupled between the first transceiver terminal TR1 and the second transceiver terminal TR2.

[0022] In some embodiments, in the hybrid RF filter 10, the series path may include a capacitor and a resonator connected in series. As shown, a first series capacitor CS1 may be coupled to a first transceiver terminal TR1, and a first series resonator RS1 may be coupled to the first series capacitor CS1. Similarly, a second series capacitor CS2 may be coupled to a second transceiver terminal TR2, and a second series resonator RS2 may be coupled to the second series capacitor CS2. In other words, the first series capacitor CS1, the first series resonator RS1, the second series resonator RS2, and the second series capacitor CS2 may be connected in series sequentially between the first transceiver terminal TR1 and the second transceiver terminal TR2.

[0023] In a further embodiment, in the hybrid RF filter 10, the series path may further include a third series capacitor CS3 and a fourth series capacitor CS4, which may be coupled between the first series resonator RS1 and the second series resonator RS2. Specifically, the first end of the third series capacitor CS3 may be coupled to the first series resonator RS1, and the second end may be coupled to the fourth series capacitor CS4. The first end of the fourth series capacitor CS4 may be coupled to the third series capacitor CS3, and the second end of the fourth series capacitor CS4 may be coupled to the second series resonator RS2.

[0024] In some embodiments, in the hybrid RF filter 10, the parallel path may include parallel capacitors and resonators. As shown, the parallel path may include a first parallel resonator RP1, which may couple the series path of the hybrid RF filter 10 to, for example, a first node N1. Specifically, a first end of the first parallel resonator RP1 may be coupled between a first series capacitor CS1 and a first series resonator RS1, and a second end of the first parallel resonator RP1 may be coupled to the first node N1. Similarly, the parallel path may also include a second parallel resonator RP2, which may couple the series path of the hybrid RF filter 10 to, for example, a second node N2. Specifically, a first end of the second parallel resonator RP2 may be coupled between a second series capacitor CS2 and a second series resonator RS2, and a second end of the second parallel resonator RP2 may be coupled to the second node N2.

[0025] In some embodiments, the parallel path may further include a first parallel capacitor CP1, a second parallel capacitor CP2, and a third parallel resonator RP3, which can couple the series path of the hybrid RF filter 10 to multiple nodes. As shown, the first end of the first parallel capacitor CP1 can be coupled between the first series resonator RS1 and the third series capacitor CS3, and the second end can be coupled to the third node N3. The first end of the second parallel capacitor CP2 can be coupled between the second series resonator RS2 and the fourth series capacitor CS4, and the second end can be coupled to the fourth node N4. The first end of the third parallel resonator RP3 can be coupled between the third series capacitor CS3 and the fourth series capacitor CS4, and the second end can be coupled to the fifth node N5.

[0026] In at least one of the above embodiments, such as Figure 1 As shown, the parallel resonators RP1, RP2, and RP3 are shown as a single resonator. However, the invention is not limited thereto; in other embodiments, at least one of the parallel resonators RP1, RP2, and RP3 may comprise a plurality of resonators connected in series.

[0027] In some embodiments, for example, the resonator may include a surface acoustic wave (SAW) resonator, a bulk acoustic wave (BAW) resonator, and other suitable resonators. In some embodiments, the hybrid RF filter 100 may be, for example, a low-pass filter, a high-pass filter, a band-pass filter, a band-stop filter, etc. For example, in the case of a high-pass filter, the capacitors and resonators in the hybrid RF filter 100 can be used to filter out lower frequency RF signals, thereby allowing higher frequency (e.g., above a preset frequency) RF signals to pass through. Further, the preset frequency may be determined by, for example, the equivalent capacitance value of each capacitor and each resonator. Moreover, the at least one resonator may have a resonant frequency, which may be determined by the material and parameters of the resonator. For example, the resonator may be, for example, a thin film bulk acoustic resonator (FBAR) including a piezoelectric film, whose resonant frequency may be determined by, for example, parameters such as the material and thickness of the piezoelectric film.

[0028] For example, a thin-film bulk acoustic wave resonator (FBAR) may include a substrate, a lower electrode, a piezoelectric thin film, a upper electrode, and a passivation layer. The substrate typically includes materials such as silicon (Si) or quartz, which can be used to provide structural support. The lower or upper electrode may be located on the substrate and typically includes metals such as molybdenum (Mo), copper (Cu), aluminum (Al), gold (Au), platinum (Pt), tungsten (W), other suitable metals, and combinations thereof. The piezoelectric thin film may be located between the lower and upper electrodes and may include, for example, materials such as zinc oxide (ZnO), aluminum nitride (AlN), lithium niobate (LiTaO3, LT), lithium niobate (LN), quartz (QZ), lead titanate (PTO), lead zirconate titanate (PZT), or combinations thereof. The passivation layer may be a protective film located on the upper electrode, used to protect the device structure and electrical characteristics. In some embodiments, the resonant frequency of the FBAR may be determined by the physical dimensions and material properties of the piezoelectric thin film. Different resonant frequencies can be achieved by changing the size and thickness of the piezoelectric thin film. Thin-film bulk acoustic resonators (TIAs) exhibit high frequency stability and a high quality factor, providing accurate frequency output. Furthermore, their frequency varies minimally with temperature, allowing them to operate over a wide temperature range.

[0029] In some embodiments, the hybrid RF filter 10 may further include a first matching circuit 12 and a second matching circuit 14. For example, the first matching circuit 12 may be coupled to a first transceiver terminal TR1, and the second matching circuit 14 may be coupled to a second transceiver terminal TR2. In the above embodiments, the series path and the parallel path may be located between the first matching circuit 12 and the second matching circuit 14. Specifically, a first terminal of the first matching circuit 12 may be coupled to the first transceiver terminal TR1, and a second terminal may be coupled to a first series capacitor CS1 in the series path. Similarly, a first terminal of the second matching circuit 14 may be coupled to a second series capacitor CS2 in the series path, and a second terminal may be coupled to the second transceiver terminal TR2.

[0030] In a specific implementation, the first series capacitor CS1 can be directly coupled to the second terminal of the first matching circuit 12. That is, the first series capacitor CS1 and the first matching circuit 12 can be directly connected by a wire without any other active or passive components in between. The second series capacitor CS2 can be directly coupled to the first terminal of the second matching circuit 12. That is, the second series capacitor CS2 and the second matching circuit 14 can be directly connected by a wire without any other active or passive components in between.

[0031] For example, the first matching circuit 12 may include a parallel inductor and a series capacitor, coupled between the first transceiver terminal TR1 and the first series capacitor CS1. The first matching circuit 12 can be used to match the input impedance to a specific impedance value (e.g., 50 ohms) to reduce the reflection of the input RF signal, allowing it to be transmitted substantially entirely to the hybrid RF filter 10. The second matching circuit 14 may also include a parallel inductor and a series capacitor, coupled between the second transceiver terminal TR2 and the second series capacitor CS2. The second matching circuit 14 can be used to match the output impedance to a specific impedance value (e.g., 50 ohms) to reduce the reflection of the input RF signal, allowing it to be transmitted substantially entirely to the second transceiver terminal TR2. The components of the above matching circuits are merely examples and are not intended to limit the invention. In other embodiments, the matching circuit may omit at least one component, or may include more components.

[0032] In at least one of the above embodiments, in the series path of the hybrid RF filter 10, the capacitance values ​​of the first series capacitor CS1 and the second series capacitor CS2 may be substantially the same, the capacitance values ​​of the third series capacitor CS3 and the fourth series capacitor CS4 may be substantially the same, or the equivalent capacitance values ​​of the first series resonator RS1 and the second series resonator RS2 may be substantially the same. In other words, imagine an axis L1 located between the third series capacitor CS3 and the fourth series capacitor CS4, where the capacitors and resonators connected in series on the left (e.g., the first series capacitor CS1, the first series resonator RS1, and the third series capacitor CS3) are symmetrical to the capacitors and resonators connected in series on the right (e.g., the second series capacitor CS2, the second series resonator RS2, and the fourth series capacitor CS4). In other words, with respect to the equivalent capacitance values ​​of individual components, axis L1 may be the axis of symmetry (line symmetry) of the series path. For example, substantially the same means that the difference between the two is less than ±20%, preferably less than ±10%, and more preferably less than ±5%.

[0033] In a further embodiment, in the parallel path of the hybrid RF filter 10, the equivalent capacitance values ​​of the first parallel resonator RP1 and the second parallel resonator RP2 may be substantially the same. The capacitance values ​​of the first parallel capacitor CP1 and the second parallel capacitor CP2 may also be substantially the same. With respect to axis L1, the capacitors and resonators connected in parallel on its left side (e.g., the first parallel resonator RP1, the first parallel capacitor CP1) are symmetrical to the capacitors and resonators connected in parallel on its right side (e.g., the second parallel resonator RP2, the second parallel capacitor CP2).

[0034] In some embodiments, the first node N1, the second node N2, the third node N3, the fourth node N4, and the fifth node N5 may be coupled to a reference voltage terminal, such as ground, via inductors. Alternatively, at least two of the first node N1, the second node N2, the third node N3, the fourth node N4, and the fifth node N5 may be coupled to the reference voltage terminal via a common inductor. The inductor may include, for example, a planar wire-wound inductor, a three-dimensional wire-wound inductor, etc. In some embodiments, the first node N1, the second node N2, the third node N3, the fourth node N4, and the fifth node N5 may be coupled to the reference voltage terminal via transmission lines, and the transmission lines have parasitic inductance. Alternatively, at least two of the first node N1, the second node N2, the third node N3, the fourth node N4, and the fifth node N5 may be coupled to the reference voltage terminal via a common transmission line.

[0035] Figure 2 This is a circuit diagram of a hybrid radio frequency filter 20 according to an embodiment of the present invention. The hybrid radio frequency filter 20 can be similar to... Figure 1The similarities to the hybrid RF filter 10 will not be repeated here; only the main differences are described below. In the hybrid RF filter 20, the parallel path may include a first parallel capacitor CP1, which can couple the series path of the hybrid RF filter 20 to, for example, a first node N1. Specifically, the first terminal of the first parallel capacitor CP1 can be coupled between the first series capacitor CS1 and the first series resonator RS1, and the second terminal can be coupled to the first node N1. Similarly, the parallel path may also include a second parallel capacitor CP2, which can couple the series path of the hybrid RF filter 20 to, for example, a second node N2. Specifically, the first terminal of the second parallel capacitor CP2 can be coupled between the second series capacitor CS2 and the second series resonator RS2, and the second terminal can be coupled to the second node N2.

[0036] In some embodiments, the parallel path may further include a first parallel resonator RP1, a second parallel resonator RP2, and a third parallel capacitor CP3, which can couple the series path of the hybrid RF filter 20 to multiple nodes. As shown, the first end of the first parallel resonator RP1 can be coupled between the first series resonator RS1 and the third series capacitor CS3, and the second end can be coupled to the third node N3. The first end of the second parallel resonator RP2 can be coupled between the second series resonator RS2 and the fourth series capacitor CS4, and the second end can be coupled to the fourth node N4. The first end of the third parallel capacitor CP3 can be coupled between the third series capacitor CS3 and the fourth series capacitor CS4, and the second end can be coupled to the fifth node N5.

[0037] In at least one of the above embodiments, in the parallel path of the hybrid RF filter 20, the capacitance values ​​of the first parallel capacitor CP1 and the second parallel capacitor CP2 may be substantially the same. The equivalent capacitance values ​​of the first parallel resonator RP1 and the second parallel resonator RP2 may be substantially the same. With respect to axis L1, the capacitors and resonators connected in parallel on its left side (e.g., the first parallel capacitor CP1, the first parallel resonator RP1) are symmetrical to the capacitors and resonators connected in parallel on its right side (e.g., the second parallel capacitor CP2, the second parallel resonator RP2).

[0038] In some embodiments, the hybrid RF filter 20 may further include a first matching circuit 22 and a second matching circuit 24, which may be similar to the first matching circuit 12 and the second matching circuit 14 of the hybrid RF filter 10, respectively, and will not be described in detail here. The first node N1, the second node N2, the third node N3, the fourth node N4, and the fifth node N5 of the hybrid RF filter 20 may also be similar to the first node N1, the second node N2, the third node N3, the fourth node N4, and the fifth node N5 of the hybrid RF filter 10, respectively, and will not be described in detail here.

[0039] In the hybrid RF filter of at least one embodiment of the present invention, the capacitors and resonators can be arbitrarily combined, connected in series, or connected in parallel to form a filter usable for a specific frequency band. In a specific embodiment, the capacitors in the series path of the hybrid RF filter can be directly coupled to the matching circuit. For example, the first series capacitor CS1 can be directly coupled to the first matching circuit 12 (or the first matching circuit 22), and / or the second series capacitor CS2 can be directly coupled to the second matching circuit 22 (or the second matching circuit 24). In this case, the hybrid RF filter can achieve better filtering performance. In summary, compared to filters that use all capacitors or all resonators, the hybrid RF filter of at least one embodiment of the present invention can use a combination of capacitors and resonators in the series path and / or parallel path, which can increase the overall bandwidth of the filter to meet the frequency band required by the application scenario.

[0040] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made in accordance with the claims of the present invention shall fall within the scope of the present invention.

Claims

1. A hybrid radio frequency filter, characterized in that, include: The first receiving and transmitting end; A second transmitting and receiving end; The first series capacitor; A second capacitor in series; A first series resonator; and A second series resonator; The first series capacitor, the first series resonator, the second series resonator, and the second series capacitor are sequentially connected in series between the first transceiver terminal and the second transceiver terminal.

2. The hybrid radio frequency filter according to claim 1, characterized in that, Also includes: A first matching circuit, comprising: A first end, coupled to the first transceiver end; and A second terminal is coupled to the first series capacitor; and A second matching circuit, comprising: One terminal is coupled to the second series capacitor; and A second end is coupled to the second transceiver end.

3. The hybrid radio frequency filter according to claim 2, characterized in that, The first series capacitor is directly coupled to the second terminal of the first matching circuit.

4. The hybrid radio frequency filter according to claim 2, characterized in that, The second series capacitor is directly coupled to the first terminal of the second matching circuit.

5. The hybrid radio frequency filter according to claim 1, characterized in that, The first series capacitor has the same capacitance value as the second series capacitor.

6. The hybrid radio frequency filter according to claim 1, characterized in that, The first series resonator has the same equivalent capacitance value as the second series resonator.

7. The hybrid radio frequency filter according to claim 1, characterized in that, Also includes: A third series capacitor includes: A first terminal is coupled to the first series resonator; and One second end; and A fourth series capacitor, including: A first terminal is coupled to the second terminal of the third series capacitor; and One of the second terminals is coupled to the second series resonator; The capacitance values ​​of the third series capacitor and the fourth series capacitor are essentially the same.

8. The hybrid radio frequency filter according to claim 7, characterized in that, further include: At least one first parallel resonator, comprising: A first terminal is coupled between the first series capacitor and the first series resonator; and A second end, coupled to a first node; and At least one second parallel resonator, including: A first terminal is coupled between the second series resonator and the second series capacitor; and A second end is coupled to a second node.

9. The hybrid radio frequency filter according to claim 8, characterized in that, The at least one first parallel resonator includes a plurality of resonators connected in series; and The at least one second parallel resonator includes a plurality of resonators connected in series.

10. The hybrid radio frequency filter according to claim 8, characterized in that, Also includes: A first parallel capacitor includes: A first terminal is coupled between the first series resonator and the third series capacitor; and A second end, coupled to a third node; and A second parallel capacitor includes: A first terminal is coupled between the fourth series capacitor and the second series resonator; and A second end is coupled to a fourth node.

11. The hybrid radio frequency filter according to claim 10, characterized in that, Also includes: A third parallel resonator, comprising: One end is coupled between the third series capacitor and the fourth series capacitor; and A second end is coupled to a fifth node.

12. The hybrid radio frequency filter according to claim 7, characterized in that, further... include: At least one first parallel capacitor, including: A first terminal is coupled between the first series capacitor and the first series resonator; and A second end, coupled to a first node; and At least one second parallel capacitor, including: A first terminal is coupled between the second series resonator and the second series capacitor; and A second end is coupled to a second node.

13. The hybrid radio frequency filter according to claim 12, characterized in that, Also includes: A first parallel resonator, comprising: A first terminal is coupled between the first series resonator and the third series capacitor; and A second end, coupled to a third node; and A second parallel resonator, comprising: A first terminal is coupled between the fourth series capacitor and the second series resonator; and A second end is coupled to a fourth node.

14. The hybrid radio frequency filter according to claim 13, characterized in that, Also includes: A third parallel capacitor includes: One end is coupled between the third series capacitor and the fourth series capacitor; and A second end is coupled to a fifth node.

15. The hybrid radio frequency filter according to claim 11 or 14, characterized in that, The first node, the second node, the third node, the fourth node, and the fifth node are each coupled to a reference voltage terminal via an inductor; or The first node, the second node, the third node, the fourth node, and the fifth node, at least two of which are coupled to a reference voltage terminal via a common inductor.

16. The hybrid radio frequency filter according to claim 15, characterized in that, The reference voltage terminal is a ground terminal.

17. The hybrid radio frequency filter according to claim 13, characterized in that, The first series resonator, the first parallel resonator, the second series resonator, and the second parallel resonator are each a thin-film bulk acoustic resonator.

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