Cavity filter and wireless communication equipment

Abstract

The invention provides a cavity filter and wireless communication equipment, and relates to the technical field of communication. The cavity filter comprises: a resonant cavity forming a resonant cavity; the resonator is arranged in the resonant cavity; the circuit board is arranged on the outer surface of the resonant cavity, and an MEMS variable capacitor is arranged on the circuit board; the connecting piece is connected with the resonator and the circuit board; wherein the MEMS variable capacitor is electrically connected with the resonator through the connecting piece, and the cavity filter is configured to adjust the resonant frequency by controlling the capacitance value of the MEMS variable capacitor. According to the cavity filter, the circuit board provided with the MEMS variable capacitor is arranged on the resonant cavity, and the MEMS variable capacitor and the resonator are electrically connected through the connecting piece, so that the cavity filter can adjust the resonant frequency by controlling the capacitance value of the MEMS variable capacitor; therefore, the tuning function of the cavity filter can be realized by means of the circuit board through software control and the like, and an overlarge tuning structure does not need to be introduced.

Description

Technical Field

[0001] The present application relates to the field of communication technology, and in particular to a cavity filter and a wireless communication device. Background Art

[0002] Filters are one of the important components in communication systems. With the development of information technology, tunable function has become an important function of filters. Filters with tunable function can change their resonant frequency to facilitate the communication frequency band adjustment of communication systems.

[0003] Cavity filter is a filter based on resonant cavity, which uses the resonance characteristics of the resonant cavity to filter the specific frequency signal. It has good anti-interference ability and high quality factor, and is widely used in wireless communication equipment such as base stations. It can meet the requirements of wireless communication equipment such as base stations for high stability, large bandwidth, high power and other indicators. However, the tunable design of related cavity filters is not ideal, and there are usually problems such as inconvenient tuning or large tuning structure volume. Summary of the invention

[0004] In order to solve the above technical problems, a technical solution adopted in the present application is: to provide a cavity filter, the cavity filter comprising: a resonant cavity, forming a resonant cavity; a resonator, arranged in the resonant cavity; a circuit board, arranged on the outer surface of the resonant cavity, on which a MEMS variable capacitor is arranged; and a connector, which connects the resonator and the circuit board; wherein the MEMS variable capacitor is electrically connected to the resonator through the connector, and the cavity filter is configured to adjust the resonant frequency by controlling the capacitance value of the MEMS variable capacitor.

[0005] In some embodiments, the cavity filter includes a voltage controller, which is disposed on a circuit board and connected to a pin of a MEMS variable capacitor, and is used to control a voltage value of the pin to achieve control over a frequency band range of the cavity filter.

[0006] In some embodiments, the cavity filter includes a feedback device, which is disposed on a circuit board and electrically connected to the MEMS variable capacitor for collecting and feeding back state information related to temperature changes of the MEMS variable capacitor.

[0007] In some embodiments, the MEMS variable capacitor includes a varactor module, and the varactor module includes at least one MEMS varactor diode.

[0008] In some embodiments, the varactor module includes multiple MEMS varactor diodes connected in parallel, and the MEMS variable capacitor also includes an RF signal access terminal and a voltage signal control terminal. The varactor module is grounded and connected to the RF signal access terminal to form an RF link, and is connected to the voltage signal control terminal to form a DC link. The MEMS variable capacitor is configured to control the bias voltage through the voltage signal control terminal to adjust the capacitance value of the varactor module.

[0009] In some embodiments, the MEMS variable capacitor includes a power supply terminal, a voltage signal control terminal, a radio frequency signal access terminal, multiple capacitors and a radio frequency MEMS switch, and the radio frequency MEMS switch includes a power supply port, a control port, an antenna port and multiple radio frequency ports, the power supply port is connected to the power supply terminal, the control port is connected to the voltage signal control terminal, the antenna port is connected to the radio frequency signal access terminal, and the multiple radio frequency ports are respectively connected to capacitors with different capacitance values;

[0010] Among them, the antenna port is connected to one of the multiple RF ports, and the RF MEMS switch is configured to receive a control signal through the control port and adjust the connection status between the antenna port and the multiple RF ports based on the control signal to achieve adjustment of the transmission path of the RF signal.

[0011] In some embodiments, the resonant cavity includes a shell and a cover plate, the shell has an installation opening, the cover plate covers the installation opening, and is arranged together with the shell to form a resonant cavity, the circuit board is arranged on the outer surface of the cover plate, the connecting piece passes through the cover plate, and one end of the connecting piece is connected to the resonator and the other end is connected to the circuit board.

[0012] In some embodiments, the resonator has an inner cavity and is separated from the cover plate. The cavity filter also includes a tuning rod, which passes through the cover plate and is inserted into the inner cavity. The cavity filter is also configured to adjust the resonant frequency by controlling the insertion depth of the tuning rod in the inner cavity.

[0013] In some embodiments, the cavity filter includes a coupling rod and a plurality of cascaded resonant cavities, wherein the coupling rod is disposed between each two adjacent resonant cavities and is used to adjust the bandwidth of the cavity filter; wherein the plurality of cascaded resonant cavities are integrally formed, the resonant cavities of each two adjacent resonant cavities are communicated, the coupling rod is inserted into the resonant cavity, and the cavity filter is configured to adjust the bandwidth by controlling the insertion depth of the coupling rod in the resonant cavity.

[0014] Another technical solution adopted in the present application is: to provide a wireless communication device, the wireless communication device includes the above-mentioned cavity filter, and the cavity filter is used to perform frequency selection and control processing on the communication signal of the wireless communication device to reduce signal interference.

[0015] Different from the prior art, the cavity filter provided by the present application has the following beneficial effects:

[0016] The present application arranges a circuit board with a MEMS variable capacitor on the outer surface of a resonant cavity, and uses a connector to connect the circuit board and the resonator in the resonant cavity to electrically connect the MEMS variable capacitor to the resonator, so that the cavity filter can adjust the resonant frequency by controlling the capacitance value of the MEMS variable capacitor. The cavity filter can achieve a tuning function through the circuit board through software control and other methods, without introducing an overly large tuning structure, which can facilitate tuning and avoid the cavity filter from being too large in size. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 is a schematic diagram of a cross-sectional structure of a cavity filter provided in some embodiments of the present application;

[0019] Figure 2 yes Figure 1 A schematic diagram of a single cavity equivalent circuit of a cavity filter in an embodiment;

[0020] Figure 3 yes Figure 1 A schematic diagram of an equivalent circuit of a cavity filter in an embodiment;

[0021] Figure 4 is a schematic cross-sectional structure diagram of a cavity filter provided in some other embodiments of the present application;

[0022] Figure 5 yes Figure 4 A schematic diagram of a single cavity equivalent circuit of a cavity filter in an embodiment;

[0023] Figure 6 yes Figure 4 A schematic diagram of an equivalent circuit of a cavity filter in an embodiment;

[0024] Figure 7 yes Figure 4 A schematic diagram of frequency variation of a single cavity of a cavity filter in an embodiment;

[0025] Figure 8 yes Figure 4 A schematic diagram of the Q value variation of the cavity filter in the embodiment;

[0026] Fig. 9 yes Figure 1 A schematic diagram of a simulated transmission response curve of a cavity filter in an embodiment;

[0027] Fig.10 yes Figure 4 A schematic diagram of a simulated transmission response curve of a cavity filter in an embodiment;

[0028] Fig.11 is a schematic diagram of a cross-sectional structure of a cavity filter provided in some embodiments of the present application;

[0029] Fig.12 is a schematic diagram of the circuit structure of a MEMS variable capacitor provided in some embodiments of the present application;

[0030] Fig.13 is a schematic diagram of a circuit structure of a MEMS variable capacitor provided in some other embodiments of the present application;

[0031] Fig.14 is a flow chart of a frequency control method of a cavity filter provided in some embodiments of the present application;

[0032] Fig.15 is a partial structural schematic diagram of a cavity filter provided in some embodiments of the present application;

[0033] Fig.16 is a performance test schematic diagram of a cavity filter provided in some embodiments of the present application;

[0034] Fig.17 is a performance test schematic diagram of a cavity filter provided in some other embodiments of the present application;

[0035] Fig.18 is a schematic diagram of the structure of a cavity filter provided in some embodiments of the present application;

[0036] Fig.19 yes Fig.11 A schematic diagram of a simulated reflection response S11 curve of the cavity filter in the embodiment;

[0037] Fig. 20 yes Fig.11 A schematic diagram of a simulated reflection response S22 curve of the cavity filter in the embodiment;

[0038] Fig.21 yes Fig.11 A schematic diagram of a simulated transmission response S12 curve of the cavity filter in the embodiment;

[0039] Fig. 22 is a schematic diagram of the structure of a wireless communication device provided in some embodiments of the present application;

[0040] Fig.23 is a schematic diagram of the structure of a wireless communication device provided in some embodiments of the present application;

[0041] Fig.24 yes Fig.23 A schematic diagram of frequency band changes of a wireless communication device in an embodiment;

[0042] Fig.25 It is a schematic diagram of application scenarios of wireless communication devices provided in some embodiments of the present application. DETAILED DESCRIPTION

[0043] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0044] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. It is understood that the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0045] It should be understood that the terms "including" and "having" and any variations thereof used in the present specification and the appended claims are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products or devices.

[0046] The present application embodiment provides a cavity filter. Figure 1 , Figure 1 It is a schematic diagram of the cross-sectional structure of the cavity filter provided in some embodiments of the present application.

[0047] exist Figure 1 In the embodiment, the cavity filter 10 includes a resonant cavity 100, a resonator 200 and a tuning rod 300. The resonant cavity 100 forms a resonant cavity 101, and the resonant cavity 101 is the internal space of the resonant cavity 100. The resonator 200 is arranged in the resonant cavity 101. The tuning rod 300 is inserted into the surface of the resonant cavity 100 and extends into the resonant cavity 101.

[0048] The resonator 200 is an electronic component that can generate a resonant frequency. The resonator 200 can amplify or attenuate a signal of a specific frequency. By designing the circuit parameters of the resonator 200, such as the capacitance parameters and the inductance parameters, the cavity filter 10 can have a strong response to signals within a certain frequency range, while attenuating or suppressing signals of other frequencies, so as to achieve a selective filtering effect.

[0049] The main function of the tuning rod 300 in the cavity filter 10 is to adjust the resonant frequency of the resonant cavity 101. The cavity filter 10 can change the inductance or capacitance of the resonant cavity 101, thereby changing its resonant frequency, by changing the length of the tuning rod 300 extending into the resonant cavity 101 or its relative position to other parts of the resonant cavity 101.

[0050] Please combine Figure 1 and Figure 2 , Figure 2 yes Figure 1 Schematic diagram of a single cavity equivalent circuit of the cavity filter in the embodiment.

[0051] The resonant cavity 101 of the cavity filter 10 can be equivalent to an LC (inductor-capacitor) resonant circuit. In the resonant state, the electromagnetic field mode of the resonant cavity 101 is usually a TEM (transverse electromagnetic wave) mode, in which the electric field and the magnetic field are completely perpendicular, and the electric field is mainly concentrated between the inner and outer conductors, while the magnetic field surrounds the outer periphery of the inner and outer conductors. Among them, the surface of the resonator 200 and the surface of the resonant cavity 100 of the cavity filter 10 can be equivalent to a capacitor.

[0052] In the equivalent circuit, the inner and outer conductors of the resonant cavity 101 can be regarded as an inductor L, and the medium (usually air) between the inner and outer conductors can be regarded as a capacitor C. When the resonant cavity 101 operates at the resonant frequency, the resonant frequencies of the inductor L and the capacitor C match, so that the entire system reaches a resonant state. In this state, the electromagnetic energy of the resonant cavity 101 oscillates between the inductor and the capacitor without significant energy loss.

[0053] Please refer to Figure 3 , Figure 3 yes Figure 1 Schematic diagram of an equivalent circuit of the cavity filter in the embodiment.

[0054] Among them, the capacitors (C1, C2, C3, C4, C5, C6) and inductors (L1, L3, L5) are the main filtering components, forming a resonant network through a specific connection method. The capacitor is used to store charge, while the inductor is used to store magnetic field energy. The combination of the two determines the frequency response characteristics of the filter.

[0055] In the resonant network, the values ​​of capacitors and inductors are precisely selected to control the center frequency and bandwidth of the filter. When the input signal enters the cavity filter 10 through the filter's input port Port1 (Port2 represents the output port), it encounters the resonant circuit composed of capacitors and inductors. These circuits will resonate at a specific frequency, so that the signal of that frequency is amplified or selectively passed, while the signals of other frequencies are attenuated or blocked.

[0056] The cavity filter 10 can be composed of a plurality of resonant cavities 101 arranged in different ways, wherein each resonant cavity 101 can be equivalent to an inductor and a capacitor connected in parallel. When a signal passes through the cavity filter 10, the signal within the passband will pass through, and the signal outside the passband will be suppressed, thereby achieving a filtering effect.

[0057] exist Figure 1 In an embodiment, the cavity filter 10 can change the resonant frequency of the resonant cavity 101 by adjusting the insertion length of the tuning rod 300 in the resonant cavity 101. The tuning rod 300 can change the resonant frequency by changing the capacitance between the inner and outer conductors. Optionally, the tuning rod 300 can be a coupling screw. The cavity filter 10 can change the insertion length of the tuning rod 300 in the resonator 200 by rotating it, thereby achieving a tuning function.

[0058] However, Figure 1 The tuning method adopted by the cavity filter 10 shown is mechanical adjustment, which has the disadvantage of inconvenient control. Based on this, the present application also provides another cavity filter 10 to solve this problem.

[0059] See also Figures 4 to 6 , Figure 4 is a schematic cross-sectional structure diagram of a cavity filter provided in some other embodiments of the present application, Figure 5 yes Figure 4 A schematic diagram of a single cavity equivalent circuit of the cavity filter in the embodiment, Figure 6 yes Figure 4 Schematic diagram of an equivalent circuit of the cavity filter in the embodiment.

[0060] exist Figure 1 The cavity filter 10 shown is based on Figure 4 The cavity filter 10 shown further includes a circuit board 400 and a connector 500. A MEMS variable capacitor 410 is disposed on the circuit board 400. The capacitance value of the MEMS variable capacitor 410 can be varied. Figure 5 The circuit diagram shown can be considered as Figure 2 An adjustable capacitor is connected in parallel on the basis of the circuit diagram shown, and its total capacitance value is the sum of the capacitance values ​​of the fixed capacitor C1 and the parallel adjustable capacitor Ct. Figure 6The circuit diagram shown can be considered as Figure 3 A plurality of adjustable capacitors are connected in parallel on the basis of the circuit diagram shown. The contents described above will not be repeated here.

[0061] The MEMS variable capacitor 410 is electrically connected to the resonator 200 through the connector 500. The cavity filter 10 is configured to adjust the resonant frequency by controlling the capacitance value of the MEMS variable capacitor 410. The circuit board 400 may be disposed on the outer surface of the resonant cavity 100. The connector 500 may connect the resonator 200 and the circuit board 400, and the MEMS variable capacitor 410 may be directly or indirectly connected to the connector 500.

[0062] Among them, the circuit board 400 is a printed circuit board (PCB), which can provide mechanical support for fixing and assembling various electronic components such as integrated circuits, and realize wiring and electrical connection between these components. MEMS is the abbreviation of Micro ElectroMechanical Systems, that is, micro-electromechanical systems. MEMS elements are high-value-added elements that integrate mechanical parts, electronic circuits, sensors, and actuators on a circuit board using micro-machining technology. MEMS variable capacitor 410 may include a capacitor element with a variable capacitance value processed on the circuit board 400 using micro-machining technology.

[0063] It should be noted that the arrangement of the MEMS variable capacitor 410 on the circuit board 400 is not limited to micro-machining. Other arrangement methods include, for example, thin film deposition technology, which utilizes physical vapor deposition (PVD) or chemical vapor deposition (CVD) to deposit one or more layers of metal films, such as copper, gold or titanium, on the circuit board 400 as electrodes of the capacitor; and photolithography and etching technology, which utilizes photoresist and a mask plate to form a desired graphic structure on the circuit board 400, and transfers the graphic on the mask plate to the photoresist through steps such as exposure and development. Then, wet etching or dry etching is used to remove the portion of the circuit board 400 that is not protected by the photoresist to form the desired groove or hole structure. These structures can be used as the dielectric layer of the capacitor or the isolation layer between the electrodes; and packaging and integration technology, which encapsulates the prepared MEMS variable capacitor 410 and the circuit board 400, and integrates the MEMS variable capacitor 410 with other electronic components on the circuit board 400 to form a complete electronic system.

[0064] The formula for the resonant frequency of the cavity filter 10 is as follows:

[0065]

[0066] The magnitude of the resonant frequency Fr is inversely proportional to the magnitude of the capacitance value C. When the capacitance value C changes, the resonant frequency FR will also change.

[0067] The capacitance formula is as follows:

[0068] C = (εS) / (4πkd);

[0069] Where (ε) / (4πk) is a constant, S is the relative area of ​​the two electrodes of the capacitor, and d is the distance between the two electrodes of the capacitor. When S and d change, the capacitance value C will also change, and thus the resonant frequency Fr will also change. When the resonant frequency of each single cavity of the cavity filter 10 shifts at the same time, the cavity filter 10 as a whole will shift in frequency.

[0070] Please refer to Figure 7 and Figure 8 , Figure 7 yes Figure 4 A schematic diagram of the frequency variation of a single cavity of the cavity filter in the embodiment, Figure 8 yes Figure 4 Schematic diagram of the Q value change of the cavity filter in the embodiment. Figure 7 As shown, the resonant frequency (vertical axis, unit Hz) of the cavity filter 10 decreases as the capacitance value (horizontal axis, unit pF) increases. Figure 7 and Figure 8 As shown, the Q value of the cavity filter 10 ( Figure 8 The change trends of the vertical axis) and the resonant frequency are roughly the same, which shows that the tuning structure of the cavity filter 10 will not lead to an increase in insertion loss.

[0071] exist Figure 4 In the embodiment, the cavity filter 10 can adjust the resonant frequency by controlling the capacitance value of the MEMS variable capacitor 410. The cavity filter 10 can also adjust the resonant frequency by controlling the extension length of the tuning rod 300 in the resonant cavity 101. In other words, the cavity filter 10 can include mechanical adjustment and MEMS adjustment, and has the characteristic of dual tunability.

[0072] Among them, the frequency deviation of the cavity filter 10 can be controlled by mechanical adjustment and MEMS adjustment. The cavity filter 10 can adjust the parameters to the optimum by using the mechanical adjustment structure, and then use the MEMS adjustment structure to adjust, so as to reduce the complexity of the product, reduce the production difficulty of the cavity filter 10, and improve the production efficiency. In other embodiments, the cavity filter 10 may not use mechanical adjustment, that is, no tuning rod 300 is provided, but only use MEMS adjustment.

[0073] Please combine Figure 3 and Figure 6 See also Fig. 9 and Fig.10 , Fig. 9 yes Figure 1A schematic diagram of a simulated transmission response curve of a cavity filter in an embodiment, Fig.10 yes Figure 4 A schematic diagram of a simulated transmission response curve of the cavity filter in the embodiment. Fig. 9 and Fig.10 The simulated transmission response S11 curve and the simulated transmission response S21 curve are shown. The S11 curve represents the Figure 3 or Figure 6 The reflection coefficient of port 1 (port1) is shown in Figure 1, and S21 represents the transmission coefficient of the signal from port 1 to port 2 (port2). Fig. 9 and Fig.10 By comparing the simulation waveforms, we can see that Figure 4 The cavity filter 10 of the embodiment is Figure 1 After an adjustable capacitor is added to the cavity filter 10 of the embodiment, the frequency point of the cavity filter 10 shifts from 351-355 MHz to 346-350 MHz.

[0074] See also Fig.11 , Fig.11 It is a schematic diagram of the cross-sectional structure of the cavity filter provided in some embodiments of the present application.

[0075] In some embodiments, the resonant cavity 100 of the cavity filter 10 may include a housing 110 and a cover plate 120. The housing 110 is provided with an installation opening 102. The cover plate 120 covers the installation opening 102 and is arranged with the housing 110 to form a resonant cavity 101. The resonator 200 is arranged in the resonant cavity 101. A circuit board 400 provided with a MEMS variable capacitor 410 may be arranged on the outer surface of the cover plate 120. The circuit board 400 and the resonator 200 may be located on opposite sides of the cover plate 120, respectively. Among them, the housing 110 may be groove-shaped, and its internal space may be used to form the resonant cavity 101, and its notch forms the installation opening 102. The cover plate 120 may be covered on the housing 110 and block the installation opening 102 to cooperate with the housing 110 to form a closed resonant cavity 101.

[0076] The resonator 200 and the MEMS variable capacitor 410 are electrically connected through a connector 500, which is not limited to contact or spatial coupling. The connector 500 can be inserted into the cover plate 120, and one end of the connector 500 is connected to the resonator 200 and the other end is connected to the circuit board 400. The connector 500 can be a rod. Optionally, the connector 500 can be integrally formed with the resonator 200. In other embodiments, the connector 500 can also be other structures, such as a lead. Among them, the connector 500 can directly contact the MEMS variable capacitor 410 to achieve electrical connection between the MEMS variable capacitor 410 and the resonator 200. The connector 500 can also be electrically connected to the MEMS through the line on the circuit board 400.

[0077] In the embodiment of the present application, the cavity filter 10 can adjust the resonant frequency by controlling the capacitance value of the MEMS variable capacitor 410, so that the cavity filter 10 can achieve the tuning function through the circuit board 400 by means of software control, etc., and there is no need to introduce an overly large tuning structure, which can facilitate tuning while avoiding the cavity filter 10 from being too large. Among them, the MEMS variable capacitor 410 is a structure with adjustable capacitance value, for example, it can be one or more MEMS components, or it can be a module composed of multiple components and circuits, which can be selected according to actual conditions. The structure of the MEMS variable capacitor 410 provided in some embodiments of the present application is shown below.

[0078] See also Fig.12 , Fig.12 Schematic diagram of the circuit structure of the MEMS variable capacitor 410 provided in some embodiments of the present application.

[0079] In some embodiments, the MEMS variable capacitor 410 includes a varactor module 411, and the varactor module 411 includes at least one MEMS varactor diode 412. The MEMS varactor diode 412 is a MEMS component whose junction capacitance can change with the change of the applied voltage. The cavity filter 10 can adjust the junction capacitance of the MEMS varactor diode 412 by controlling the voltage, thereby adjusting the capacitance value of the varactor module 411.

[0080] Optionally, the varactor module 411 includes a plurality of MEMS varactor diodes 412 connected in parallel. The number of the MEMS varactor diodes 412 is, for example but not limited to, Fig.12 When adjusting the capacitance value, the voltage provided by the voltage source will be evenly distributed to the multiple MEMS varactor diodes 412. As the bias voltage changes, the capacitance value of each MEMS varactor diode 412 will also change accordingly. These changes in capacitance values ​​will directly affect the total capacitance value of the entire parallel capacitor structure.

[0081] Among them, the MEMS variable capacitor 410 also includes an RF signal access terminal RF-IN and a voltage signal control terminal VT-VBPF. The variable capacitance module 411 is grounded and connected to the RF signal access terminal RF-IN to form an RF link, and is connected to the voltage signal control terminal VT-VBPF to form a DC link. The MEMS variable capacitor 410 can be configured to adjust the capacitance value of the variable capacitance module 411 by controlling the bias voltage through the voltage signal control terminal VT-VBPF. The RF signal input terminal RF-IN is connected to the resonator 200 through the connector 500.

[0082] The RF link is the RF signal transmission link, and the DC link is the control voltage link. In some embodiments, the MEMS variable capacitor 410 may also include a resistor or a capacitor electrically connected to the variable capacitance module 411 to achieve functions such as DC isolation and filtering.

[0083] like Fig.12 As shown, on the DC link, the MEMS variable capacitor 410 may also include a parallel capacitor C1 and a capacitor C2, and the capacitor C1 and the capacitor C2 are grounded, which can be used to filter out DC power supply noise. On the DC link, the MEMS variable capacitor 410 may also include a resistor R1, and the resistor R1 may be connected in series with the variable capacitance module 411 and grounded to adjust the DC control voltage and current.

[0084] In the RF link, the MEMS variable capacitor 410 may also include a resistor R2 and a capacitor C9, which may be connected in series and connected in series with the variable capacitance module 411 to ground. Among them, the resistor R2 may be used as a reserved debugging structure. The capacitor C9 may be used for direct current isolation, that is, the characteristic of the capacitor being able to isolate (or isolate) direct current (DC) in the circuit is utilized to allow only alternating current (AC) to pass through, while preventing direct current from passing through. The direct current isolation effect of the capacitor C9 may be used to extract the AC component in the RF signal, filter out unnecessary components such as DC bias, and thereby obtain a purer signal.

[0085] See also Fig.13 , Fig.13 It is a schematic diagram of the circuit structure of a MEMS variable capacitor provided in some other embodiments of the present application.

[0086] In some embodiments, the MEMS variable capacitor 410 includes a radio frequency MEMS switch 413. Fig.13 As shown, the RF MEMS switch 413 includes a power port VDD, control ports (VC1, VC2), an antenna port ANT, and multiple RF ports (RF1, RF2, RF3, RF4). The RF MEMS switch 413 also includes ground ports (GND1, GND2).

[0087] The MEMS variable capacitor 410 further includes a power supply terminal VT-SWITCH, voltage signal control terminals (VT-VC1, VT-VC2), a radio frequency signal access terminal RF-IN, and a plurality of capacitors (C1, C2, C3, C4).

[0088] The power port VDD is connected to the power terminal VT-SWITCH to provide the necessary voltage for the circuit. The control ports (VC1, VC2) are connected to the voltage signal control terminals (VT-VC1, VT-VC2). Specifically, the control port VC1 is connected to the voltage signal control terminal VT-VC1, and the control port VC2 is connected to the voltage signal control terminal VT-VC2 to adjust the path of the RF signal.

[0089] The antenna port ANT is connected to the RF signal access terminal RF-IN. Multiple RF ports (RF1, RF2, RF3, RF4) are respectively connected to capacitors (C1, C2, C3, C4) with different capacitance values. Specifically, the RF port RF1 is connected to the capacitor C1, the RF port RF2 is connected to the capacitor C2, the RF port RF3 is connected to the capacitor C3, and the RF port RF4 is connected to the capacitor C4. The capacitance values ​​of capacitor C1, capacitor C2, capacitor C3, and capacitor C4 are different. In other embodiments, the number of capacitors with different capacitance values ​​can also be less than 4 or more than 4, and the RF MEMS switch 413 has a corresponding number of RF ports.

[0090] Among them, the antenna port ANT is connected to one of the multiple RF ports (RF1, RF2, RF3, RF4), and the RF MEMS switch 413 is configured to receive a control signal through the control port (VC1, VC2) and adjust the connection status between the antenna port ANT and the multiple RF ports (RF1, RF2, RF3, RF4) based on the control signal to achieve the adjustment of the transmission path of the RF signal.

[0091] Each RF port (RF1, RF2, RF3, RF4) is connected to the antenna port ANT through capacitors (C1, C2, C3, C4) of different capacitance values, and these capacitors are used to adjust the RF performance of the filter. For example, when the voltage of the control port VC2 increases, the RF MEMS switch 413 can connect the RF port RF4 to the antenna port ANT, and the capacitor C4 is used as a matching element. For another example, when the voltage of the control port VC1 changes, the RF MEMS switch 413 can switch to the RF port RF3 and use the capacitor C3 for matching.

[0092] When the control port VC1 or the control port VC2 receives a control signal and reaches a specific voltage, the RF MEMS switch 413 will accordingly turn on the corresponding RF port (RF1, RF2, RF3, RF4) to the antenna port ANT, and select the corresponding adjustment capacitor. The MEMS variable capacitor 410 can control the on and off of the RF port RF4, RF port RF3, RF port RF2, and RF port RF1 through the power supply terminal VT-SWITCH, the voltage signal control terminal VT-VC1, and the voltage signal control terminal VT-VC2. This design allows the circuit to dynamically adjust the transmission path of the RF signal according to the external control signal to meet different communication requirements.

[0093] Optionally, the MEMS variable capacitor 410 further includes: Fig.13 The capacitor C5, capacitor C6 and capacitor C7 are shown. Capacitor C5 is connected in parallel to the power supply port VDD and grounded, capacitor C6 is connected in parallel to the voltage signal control terminal VT-VC1 and grounded, and capacitor C7 is connected in parallel to the voltage signal control terminal VT-VC2 and grounded, for filtering and matching RF signals. The MEMS variable capacitor 410 may also include a capacitor C8 for DC isolation, and capacitor C8 is connected in series to the antenna port ANT and the RF signal access terminal RF-IN. The MEMS variable capacitor 410 may also include a resistor R3 connected in series to the antenna port ANT and the RF signal access terminal RF-IN, and the resistor R3 is used for matching the antenna port ANT, which can further ensure the stable transmission of the RF signal.

[0094] The cavity filter 10 provided in the embodiment of the present application can conveniently adjust the resonant frequency by controlling the capacitance value of the MEMS variable capacitor 410. Among them, the capacitance value of the MEMS variable capacitor 410 can change according to the change of the control voltage. The cavity filter 10 can control the voltage through a software algorithm, and then control the capacitance value of the MEMS variable capacitor 410, so as to achieve the effect of controlling the frequency band range of the cavity filter 10.

[0095] See also Fig.14 , Fig.14 It is a flow chart of a frequency control method of a cavity filter provided in some embodiments of the present application.

[0096] In some embodiments, the frequency control method of the cavity filter 10 may include the following steps:

[0097] S1: Read the device frequency band configuration. The device may be a communication device used by the cavity filter 10. When the frequency band of the device changes, the cavity filter 10 may execute step S1.

[0098] S2: Loading a mapping table. The mapping table may be stored in the cavity filter 10 in advance.

[0099] S3: Analyze the voltage value according to the mapping table and the device frequency band. The adjustable frequency band of the device and the voltage value are in a one-to-one correspondence.

[0100] S4: Control voltage. After determining the voltage value corresponding to the device frequency band according to the mapping table, control the control voltage of the cavity filter 10 to control the capacitance value of the MEMS variable capacitor 410 to reach a preset value. In step S4, the cavity filter 10 can be controlled by Fig.12 The voltage signal control terminal VT-VBPF shown in FIG. Fig.13 The voltage signal control terminal VT-VC1 and the voltage signal control terminal VT-VC2 shown control the voltage.

[0101] See also Fig.15 , Fig.15 It is a partial structural schematic diagram of the cavity filter provided in some embodiments of the present application.

[0102] In some embodiments, the cavity filter 10 includes a voltage controller 420 for controlling a voltage to control the capacitance value of the MEMS variable capacitor 410. The voltage controller 420 can be disposed on the circuit board 400 and connected to the pin of the MEMS variable capacitor 410, and can be used to control the voltage value of the pin to control the frequency band range of the cavity filter 10. For example, the voltage controller 420 can be connected to the circuit board 400. Fig.12 The voltage signal control terminal VT-VBPF is connected to the Fig.13 The voltage signal control terminal VT-VC1 is shown to be connected to the voltage signal control terminal VT-VC2. Of course, the voltage controller 420 can also be set at other locations.

[0103] The electronic components used by the voltage controller 420 can be selected according to actual conditions, such as but not limited to digital potentiometers, operational amplifiers (Op-Amp), digital-to-analog converters (DAC), programmable voltage sources, application-specific integrated circuits (ASICs), etc.

[0104] In the embodiment of the present application, the cavity filter 10 can be used as follows: Fig.14 The software algorithm shown controls the voltage value of the corresponding pin of the MEMS variable capacitor 410 by configuring the voltage controller 420, thereby achieving the function of controlling the frequency band range of the adjustable filter.

[0105] In some embodiments, the cavity filter 10 may include a feedback device 430 , which is disposed on the circuit board 400 and electrically connected to the MEMS variable capacitor 410 , and is used to collect and feed back state information of the MEMS variable capacitor 410 related to temperature changes.

[0106] It is understandable that the MEMS variable capacitor 410 and other components of the cavity filter 10 may produce characteristic changes in high and low temperature environments.

[0107] For example, in a high temperature environment, the MEMS variable capacitor 410 may undergo characteristic changes such as changes in capacitance value and reduced insulation resistance; the reason for the change in capacitance value is that high temperature may cause thermal expansion of the dielectric material inside the capacitor, thereby affecting the dielectric constant and causing the capacitance value to change; the reason for the reduction in insulation resistance is that as the temperature rises, the electronic activity increases, and the insulation resistance inside the capacitor may decrease, resulting in an increase in leakage current, thereby affecting the stability and life of the capacitor.

[0108] For example, in a low-temperature environment, the MEMS variable capacitor 410 may experience characteristic changes such as changes in capacitance value, leakage current, inter-electrode resistance, and internal loss; among which, the reason for the change in capacitance value is that in a low-temperature environment, the resistivity of the metal may decrease, and the capacitance value of the capacitor is related to its resistivity, so the capacitance value may increase. At the same time, the dielectric constant inside the capacitor may also increase as the temperature decreases, further causing a change in capacitance value; the reason for the change in leakage current is that low temperature may cause the dielectric constant to increase, and the resistance to the flow of electrons in the medium increases, thereby causing the leakage current to decrease; the reason for the change in inter-electrode resistance is that the metal conductor inside the capacitor may become more fragile due to low temperature, resulting in tiny pits and oxides on the metal surface, which may cause the inter-electrode resistance of the capacitor to increase; the reason for the change in internal loss is that in a low-temperature environment, the fluidity of molecules and ions in the medium may decrease, and the internal losses caused by the movement of molecules and ions caused by the electric field and friction may also decrease accordingly.

[0109] The feedback device 430 is an electronic component that can detect this characteristic change and feed it back, such as but not limited to a capacitor-voltage converter (CVC), an insulation resistance tester, a leakage current monitor, a temperature sensor, an application-specific integrated circuit (ASIC) chip, etc. The specific electronic component used can be determined based on the data required for feedback.

[0110] In the embodiment of the present application, the state information related to the temperature change of the MEMS variable capacitor 410 can be collected and fed back through the feedback device 430, and then according to the collected feedback data, the software algorithm can automatically correct to obtain a more accurate frequency response, which is conducive to improving the frequency adjustment accuracy of the cavity filter 10 and making the product more intelligent. Among them, the feedback object of the feedback device 430 can be the voltage controller 420, and can also be designed as other objects as needed, such as the background.

[0111] Please continue reading Fig.11In some embodiments, the resonator 200 may have an inner cavity 201. The cavity filter 10 may further include a tuning rod 300, which passes through the cover plate 120 and is inserted into the inner cavity 201. The cavity filter 10 may also be configured to adjust the resonant frequency by controlling the insertion depth of the tuning rod 300 in the inner cavity 201.

[0112] The cavity filter 10 can change the capacitance value of the resonant cavity 101 and thus change its resonant frequency by changing the length of the tuning rod 300 extending into the inner cavity 201. The resonator 200 can be separated from the cover plate 120. The material between the resonator 200 and the cover plate 120 can determine the dielectric constant ε in the capacitance formula C = (εS) / (4πkd). The material between the resonator 200 and the cover plate 120 can be air, in which case the dielectric constant is equivalent to 1. In other embodiments, a dielectric plate can also be provided between the resonator 200 and the cover plate 120, and the cavity filter 10 can select a dielectric plate of a corresponding material according to the required dielectric constant.

[0113] The embodiment of the present application can achieve control of the resonant frequency of the cavity filter 10 by a MEMS adjustment method of adjusting the capacitance value of the MEMS variable capacitor 410 by controlling the voltage, and a mechanical adjustment method of adjusting the extension length of the tuning rod 300, so that the cavity filter 10 can be adjusted according to the required frequency when in use.

[0114] The embodiment of the present application combines mechanical adjustment and MEMS adjustment structures to enable the cavity filter 10 to vary within a certain frequency band. By adjusting the tuning rod 300, the capacitance of 0-1PF can be met, thereby reducing the types of capacitors, reducing the difficulty of product production, and helping to improve production efficiency.

[0115] Please refer to Fig.16 and Fig.17 , Fig.16 is a performance test schematic diagram of a cavity filter provided in some embodiments of the present application, Fig.17 It is a performance test schematic diagram of the cavity filter provided in other embodiments of the present application.

[0116] Compared to Fig.16 The cavity filter 10 shown, Fig.17 The resonator 200 of the cavity filter 10 shown in the figure has a skirt at one end thereof close to the cover plate 120, and its function is to reduce the frequency of the resonant cavity 101. Conventional filters need to determine the shape of the resonator 200 during production and processing according to the required frequency. For example, when the required frequency is high, the resonator 200 is processed into Fig.16 The structure without skirt shown in FIG. 1 is processed into the resonator 200 when the required frequency is low. Fig.17The structure shown has a skirt, which makes the production and processing of the product more complicated and the cost higher.

[0117] The embodiment of the present application can realize the control of the resonant frequency of the cavity filter 10 through the above-mentioned MEMS adjustment and mechanical adjustment, so there is no need to adjust the shape of the resonator 200 according to the required frequency during processing, which is conducive to reducing the processing difficulty and reducing the manufacturing cost. For example, the embodiment of the present application can process the cavity filter 10 into the following shape regardless of the required frequency: Fig.16 The skirt-free structure shown does not require a skirt to be provided for the resonator 200. Fig.16 Frequency data and Q value data, and Fig.17 It can be seen from the frequency data and Q value data that the ratios of the frequencies and Q values ​​of the two are substantially the same, which shows that the simplified structure of the resonator 200 in the embodiment of the present application will not lead to an increase in insertion loss.

[0118] It should be noted that the above embodiment shows a single cavity structure of the cavity filter 10, and the cavity filter 10 provided in the embodiment of the present application may include a plurality of resonant cavities 100. Fig.18 , Fig.18 It is a schematic diagram of the structure of the cavity filter provided in some embodiments of the present application.

[0119] In some embodiments, the cavity filter 10 may include a coupling rod 600 and a plurality of cascaded resonant cavities 100. The coupling rod 600 may be disposed between each two adjacent resonant cavities 100 to adjust the bandwidth of the cavity filter 10. The coupling rod 600 is inserted into the resonant cavity 101, and the cavity filter 10 may be configured to adjust the bandwidth by controlling the insertion depth of the coupling rod 600 in the resonant cavity 101.

[0120] In the process of adjusting the resonant frequency, the cavity filter 10 can change the coupling strength between the resonant cavities 101 by adjusting the position of the coupling rod 600, thereby affecting the bandwidth of the filter. The change in coupling strength will change the energy exchange efficiency between the resonant cavities 101, thereby affecting the passband width of the cavity filter 10.

[0121] Among them, a plurality of cascaded resonant cavities 100 can be integrally formed. The resonant cavities 101 of each two adjacent resonant cavities 100 are connected. The coupling rod 600 can be retractably inserted between two adjacent resonant cavities 100 to adjust the energy exchange efficiency between the two connected resonant cavities 101, thereby adjusting the bandwidth of the cavity filter 10. Optionally, the coupling rod 600 can be a screw rod, and the insertion depth in the resonant cavity 101 can be adjusted in a spiral manner.

[0122] See also Figures 19 to 21 , Fig.19 yes Fig.11 A schematic diagram of a simulated reflection response S11 curve of the cavity filter in the embodiment, Fig. 20 yes Fig.11 A schematic diagram of a simulated reflection response S22 curve of the cavity filter in the embodiment, Fig.21 yes Fig.11 Schematic diagram of a simulated transmission response S12 curve of the cavity filter in the embodiment.

[0123] in, Fig.19 It represents the reflection coefficient S11 of port 1 of the cavity filter 10. Fig. 20 It represents the reflection coefficient S22 of the 2 ports of the cavity filter 10. Fig.21 It represents the transmission coefficient S12 of the signal from port 1 to port 2 of the cavity filter 10. The horizontal axis corresponds to the frequency, and the unit is MHz.

[0124] in, Figures 19 to 21 Four curves are formed, named curve 1, curve 2, curve 3 and curve 4. The capacitance values ​​corresponding to each curve are different. As shown in the figure, the capacitance value corresponding to curve 1 is 1pF, the capacitance value corresponding to curve 2 is 4pF, the capacitance value corresponding to curve 3 is 7pF, and the capacitance value corresponding to curve 4 is 10pF. Among them, the m value of each curve can represent its intermediate frequency and bandwidth.

[0125] Take curve 4 as an example, its intermediate frequency is the midpoint of m1 and m2, that is, the middle value of 327MHz and 330MHz, which is 328.5MHz, and its bandwidth is the width of m1 and m2, which is 327MHz-330MHz. Similarly, the intermediate frequency of curve 3 is 353.875MHz, and the bandwidth is 352MHz-355.75MHz; the intermediate frequency of curve 2 is 385.5MHz, and the bandwidth is 383MHz-387MHz; the intermediate frequency of curve 1 is 422.5MHz, and the bandwidth is 419.75MHz-425.25MHz.

[0126] In the embodiment of the present application, the capacitance value can be controlled by MEMS adjustment or mechanical adjustment, thereby controlling the frequency of the cavity filter 10. Figures 19 to 21 It can be seen that the frequency variation trend of the cavity filter 10 is that it gradually decreases as the capacitance value increases.

[0127] The cavity filter 10 provided in the embodiment of the present application has a frequency adjustable range of up to 240MHz through the above-mentioned frequency adjustment structure design, which can realize filter normalization and is conducive to enriching product application scenarios. The cavity filter 10 provided in the embodiment of the present application has a transmission zero point, has the characteristics of low insertion loss, high suppression, high power, and miniaturization, and is highly practical. When the conventional coaxial cavity filter 10 is loaded to the size limit, the cavity filter 10 provided in the embodiment of the present application can achieve a smaller product size and lighter weight on the original basis.

[0128] The present application also provides a wireless communication device. Fig. 22 , Fig. 22 It is a schematic diagram of the structure of a wireless communication device provided in some embodiments of the present application.

[0129] The wireless communication device 20 provided in the embodiment of the present application includes the above-mentioned cavity filter 10. The cavity filter 10 can be used to perform frequency selection and control processing on the communication signal of the wireless communication device 20 to reduce signal interference. The wireless communication device 20 is, for example but not limited to, a base station.

[0130] See also Fig.23 and Fig.24 , Fig.23 is a schematic diagram of the structure of a wireless communication device provided in some embodiments of the present application, Fig.24 yes Fig.23 Schematic diagram of frequency band change of a wireless communication device in an embodiment.

[0131] In some embodiments, the wireless communication device 20 may include a signal transceiver 21, a power amplifier 22, and a duplexer 23. Among them, the signal transceiver 21 may be a TRX board, which is the full name of the transceiver board (Transceiver Board), which is one of the core components in the wireless communication system. The TRX board is responsible for converting analog signals to and from RF signals: during the transmission process, the analog signal after baseband processing is converted into an RF signal so that it can be sent out through the antenna; during the reception process, the RF signal received by the antenna is converted into an analog signal for further processing by the baseband processing system. The TRX board usually includes RF front-end processing circuits, such as a power amplifier 22, a low noise amplifier (LNA), a filter, etc., as well as necessary control logic and interface circuits.

[0132] The power amplifier 22 may be a PA board, which stands for Power Amplifier Board, and is a circuit board 400 specifically used to amplify radio frequency signals. In a wireless communication system, the power amplifier 22 is one of the core components of the radio frequency front end, and its function is to amplify the weak radio frequency signal in the transmission channel to a sufficient power level to ensure that the signal can cover a longer distance and maintain a high communication quality. The PA board usually includes a multi-stage amplification circuit, as well as necessary matching networks, protection circuits, and control logic to ensure that the power amplifier 22 can work stably and efficiently.

[0133] The cavity filter 10 provided in the embodiment of the present application can be applied to the duplexer 23. The duplexer 23 (Duplexer) is a special bidirectional three-terminal filter used to isolate the transmit and receive signals to ensure that they can work normally at the same time without interfering with each other. The duplexer 23 is usually composed of two groups of band-stop filters of different frequencies, and the frequency division function of the high-pass, low-pass or band-pass filter is utilized so that the same antenna or transmission line can be used for two signal paths. In the transmitting state, the duplexer 23 allows the transmit signal to pass through and be transmitted to the antenna, while preventing the receive signal from entering the transmit path; in the receiving state, the duplexer 23 allows the receive signal to pass through and be transmitted to the receiver, while preventing the transmit signal from entering the receive path. In this way, the duplexer 23 achieves effective isolation of the transmit and receive signals.

[0134] like Fig.24 As shown, the wireless communication device 20 of the embodiment of the present application can adjust the frequency band of the entire device by adjusting the frequency of the duplexer 23.

[0135] Take the wireless communication device 20 as a base station as an example. When a base station fails in the link with the center, the duplexer 23 frequency band of one of the transmission channels can be shifted according to the pre-set plan so that it can be interconnected with the adjacent base station, so that the adjacent base station link can be used to achieve connection with the center.

[0136] Please refer to Fig.25 , Fig.25 It is a schematic diagram of application scenarios of wireless communication devices provided in some embodiments of the present application.

[0137] In some embodiments, the wireless communication device 20 includes a transmitting unit 24 and a receiving unit 25, wherein the transmitting unit 24 is used to transmit a signal of a specific frequency band, and the receiving unit 25 is used to receive a signal of a specific frequency band. The above-mentioned cavity filter 10 can be applied to the transmitting unit 24 and the receiving unit 25, so that the frequency band of the signal transmitted by the transmitting unit 24 and the frequency band of the signal received by the receiving unit 25 can be adjusted.

[0138] In this way, the wireless communication device 20 can change the object of its communication connection by adjusting its transmission signal frequency band or receiving signal frequency band when an abnormality occurs in the communication connection with the outside. In some application scenarios, the wireless communication device 20 sends a signal to an external base station through the transmitting unit 24. When the transmitting unit 24 cannot communicate smoothly with the base station, the transmitting unit 24 can adjust its transmission signal frequency band to communicate with other base stations, such as another adjacent base station. For example, when the transmitting unit 24 cannot communicate with the base station at a frequency band of 420MHz-425MHz, it can adjust the frequency band to 430MHz-435MHz to transmit the signal to other base stations. Similarly, when the receiving unit 25 cannot communicate smoothly with the base station, it can adjust the receiving signal frequency band to receive signals sent by other base stations.

[0139] Among them, the frequency band adjustment range of the cavity filter 10 can be designed according to the needs of the wireless communication device 20. For example, when the wireless communication device 20 can only support 5MHz, the cavity filter 10 can set the frequency band adjustment to 5MHz as the adjustment unit, and the cavity filter 10 can achieve any 5MHz frequency band adjustment within 350-470MHz, which can reduce stagnant inventory. It can be understood that when the frequency band supported by the wireless communication device 20 is other values, the frequency band adjustment setting of the filter can also be changed accordingly.

[0140] Through the above-mentioned design, the embodiment of the present application enables the cavity filter 10 to form a variety of frequency band combinations, so that the number of cavity filters 10 required for the wireless communication device 20 can be greatly reduced.

[0141] It should be understood that the terms used in the specification of this application and the attached claims are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in the specification of this application and the attached claims, unless the context clearly indicates otherwise, the singular forms of "one", "an" and "the" are intended to include plural forms. As another example, the terms "first" and "second" in the description of this application are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. As another example, the meaning of "multiple" in the description of this application is two or more, unless otherwise clearly and specifically defined.

[0142] In the description of the present application, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradicting each other.

[0143] The above description is only part of the implementation methods of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the description and drawings of this application, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A cavity filter, characterized in that: The cavity filter comprises: A resonant cavity body forms a resonant cavity; a resonator, disposed in the resonant cavity; A circuit board is arranged on the outer surface of the resonant cavity, and a MEMS variable capacitor is arranged on the circuit board; and A connector, the connector connecting the resonator and the circuit board; The MEMS variable capacitor is electrically connected to the resonator through the connecting piece, and the cavity filter is configured to adjust the resonant frequency by controlling the capacitance value of the MEMS variable capacitor.

2. The cavity filter according to claim 1, characterized in that: The cavity filter comprises a voltage controller, which is arranged on the circuit board and connected to the pin of the MEMS variable capacitor, and is used to control the voltage value of the pin to achieve control of the frequency band range of the cavity filter.

3. The cavity filter according to claim 1, characterized in that: The cavity filter includes a feedback device, which is arranged on the circuit board and electrically connected to the MEMS variable capacitor, and is used to collect and feed back state information related to temperature changes of the MEMS variable capacitor.

4. The cavity filter according to claim 1, characterized in that: The MEMS variable capacitor includes a varactor module, and the varactor module includes at least one MEMS varactor diode.

5. The cavity filter according to claim 4, characterized in that: The varactor module includes a plurality of MEMS varactor diodes connected in parallel, and the MEMS variable capacitor also includes an RF signal access terminal and a voltage signal control terminal. The varactor module is grounded and connected to the RF signal access terminal to form an RF link, and is connected to the voltage signal control terminal to form a DC link. The MEMS variable capacitor is configured to adjust the capacitance value of the varactor module by controlling the bias voltage through the voltage signal control terminal.

6. The cavity filter according to claim 1, characterized in that: The MEMS variable capacitor includes a power supply terminal, a voltage signal control terminal, a radio frequency signal access terminal, a plurality of capacitors and a radio frequency MEMS switch. The radio frequency MEMS switch includes a power supply port, a control port, an antenna port and a plurality of radio frequency ports. The power supply port is connected to the power supply terminal, the control port is connected to the voltage signal control terminal, the antenna port is connected to the radio frequency signal access terminal, and the plurality of radio frequency ports are respectively connected to the capacitors with different capacitance values. The antenna port is connected to one of the multiple RF ports, and the RF MEMS switch is configured to receive a control signal through the control port and adjust the connection status between the antenna port and the multiple RF ports based on the control signal to achieve adjustment of the transmission path of the RF signal.

7. The cavity filter according to claim 1, characterized in that: The resonant cavity includes a shell and a cover plate, the shell is provided with an installation opening, the cover plate covers the installation opening and is arranged together with the shell to form the resonant cavity, the circuit board is arranged on the outer surface of the cover plate, the connecting piece passes through the cover plate, and one end of the connecting piece is connected to the resonator, and the other end is connected to the circuit board.

8. The cavity filter according to claim 7, characterized in that: The resonator has an inner cavity and is separated from the cover plate. The cavity filter also includes a tuning rod, which passes through the cover plate and is inserted into the inner cavity. The cavity filter is also configured to adjust the resonant frequency by controlling the insertion depth of the tuning rod in the inner cavity.

9. The cavity filter according to claim 1, characterized in that: The cavity filter includes a coupling rod and a plurality of cascaded resonant cavities, wherein the coupling rod is arranged between each two adjacent resonant cavities and is used to adjust the bandwidth of the cavity filter; wherein the plurality of cascaded resonant cavities are integrally formed, the resonant cavities of each two adjacent resonant cavities are communicated, the coupling rod is inserted into the resonant cavity, and the cavity filter is configured to adjust the bandwidth by controlling the insertion depth of the coupling rod in the resonant cavity.

10. A wireless communication device, characterized in that: The wireless communication device comprises the cavity filter according to any one of claims 1 to 9, and the cavity filter is used to perform frequency selection and control processing on the communication signal of the wireless communication device to reduce signal interference.

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