Radio frequency apparatus and communication device

Abstract

Provided in the embodiments of the present application are a radio frequency apparatus and a communication device, which are used for meeting the performance requirement of low insertion loss for the radio frequency apparatus. A low-pass filter circuit of the radio frequency apparatus is electrically connected between an input end and a second output end. A first resonant unit of a band-pass filter circuit comprises a second capacitor and a first inductor, wherein a first end of the second capacitor is electrically connected to the input end, and a second end of the second capacitor is electrically connected to a first end of the first inductor; and a second resonant unit of the band-pass filter circuit comprises a third capacitor and a second inductor, wherein a first end of the third capacitor is electrically connected to a first output end, a second end of the third capacitor is electrically connected to a first end of the second inductor, and a second end of the second inductor is electrically connected to a second end of the first inductor. A first capacitor is electrically connected between the second end of the second capacitor and the second end of the third capacitor. The radio frequency apparatus of the present application can reduce the insertion loss, and can meet the performance requirement of low insertion loss.

Description

Radio frequency devices and communication equipment

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on November 14, 2023, with application number 202323080441.0 and application name “Radio Frequency Device and Communication Equipment”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of radio frequency communication technology, and in particular to a radio frequency device and communication equipment. Background Art

[0003] In recent years, with the rapid advancement and widespread application of wireless communication technology, complex electromagnetic environments and other issues have become increasingly prominent. Consequently, radio frequency devices, with their advantages in suppressing interference between adjacent channels and reducing noise figures, have become irreplaceable frequency-selective components in communication equipment. However, this rapid development of wireless communication technology has also placed increasingly stringent requirements on communication equipment and even the internal radio frequency devices, such as the requirement for low insertion loss performance.

[0004] However, in the related art, it is difficult for radio frequency devices to meet the above requirements.

[0005] Summary of the Invention

[0006] The present application provides a radio frequency device and a communication device, aiming to meet the performance requirements of low insertion loss of the radio frequency device.

[0007] To achieve the above objectives, this application adopts the following technical solutions:

[0008] On the one hand, a radio frequency device is provided, comprising: a substrate, and a bandpass filter circuit, a low-pass filter circuit, an input end, a first output end, and a second output end disposed on the substrate. The low-pass filter circuit is electrically connected between the input end and the second output end. The bandpass filter circuit comprises: a first resonant unit, a second resonant unit, and a first capacitor. The first resonant unit comprises a second capacitor and a first inductor, wherein the first end of the second capacitor is electrically connected to the input end, and the second end of the second capacitor is electrically connected to the first end of the first inductor. The second resonant unit comprises a third capacitor and a second inductor, wherein the first end of the third capacitor is electrically connected to the first output end, the second end of the third capacitor is electrically connected to the first end of the second inductor, and the second end of the second inductor is electrically connected to the second end of the first inductor. The first capacitor is electrically connected between the second end of the second capacitor and the second end of the third capacitor.

[0009] The RF device provided by the present application has the following characteristics: when the RF signal received at the input end passes through the low-pass filter circuit, the band above the low-pass target frequency in the RF signal is suppressed, and the RF signal that meets the low-pass target frequency can pass through the low-pass filter circuit and be transmitted to the subsequently connected RF circuit through the second output end. When the RF signal received at the input end passes through the band-pass filter circuit, the RF signals in the high-frequency band and the low-frequency band outside the band-pass target frequency band are both suppressed. The RF signal obtained after filtering and within the band-pass target frequency band can pass through the band-pass filter circuit and be transmitted to the subsequently connected RF circuit through the first output end. The two transmission channels of the RF device respectively filter the received RF signal to obtain a RF signal that meets the target frequency band and meets the requirements. The band-pass filter circuit is composed of a first resonant unit, a second resonant unit, and a first capacitor. During operation, in addition to the transmission zero point generated by the filtering response of the first resonant unit and the second resonant unit, the parallel resonance of the first capacitor can generate a third transmission zero point, thereby improving the ability of the band-pass filter circuit to filter out higher harmonics, thereby improving the in-band matching and out-of-band suppression capabilities of the entire RF device, so that the RF device has the performance characteristics of low insertion loss.

[0010] In some embodiments, the low-pass filter circuit and the band-pass filter circuit are arranged in sequence along a first direction, and the second direction intersects the first direction. The second capacitor, the first capacitor, and the third capacitor are arranged in sequence along the second direction.

[0011] Among them, the second capacitor, the first capacitor and the third capacitor serve as the main structure of the band-pass filter circuit. By arranging the layout positions of the second capacitor, the first capacitor and the third capacitor, the layout area occupied by the entire band-pass filter circuit on the substrate can be controlled, and the size occupied by the band-pass filter circuit in the first direction can be shortened, thereby improving the utilization rate of the substrate area and realizing the miniaturization design of the circuit structure of the radio frequency device.

[0012] In some embodiments, the first inductor and the second inductor are located on a side of the first capacitor close to the low-pass filter circuit.

[0013] With this arrangement, the subsequently designed low-pass filter circuit can be used with the first and second inductors to achieve layout splicing, thereby shortening the spacing between the internal circuit structures of the RF device, and further reducing the size of the circuit structure of the RF device, thereby achieving a miniaturized design.

[0014] In addition, by placing the overall layout consisting of the second capacitor, the first capacitor and the third capacitor connected in series on a side away from the low-pass filter circuit, the edge shape of the RF device can be regularized, thereby avoiding the waste of layout area caused by the irregular shapes of the first inductor and the second inductor, and improving the utilization rate of the substrate area.

[0015] In some embodiments, the bandpass filter circuit further includes: a first matching network and a second matching network. The first matching network is electrically connected between the input terminal and the first end of the second capacitor, and the second matching network is electrically connected between the second end of the third capacitor and the first output terminal. The first matching network and the second matching network both include rectangular conductor blocks, and the width of the first matching network in the first direction is smaller than the width in the second direction, while the width of the second matching network in the first direction is larger than the width in the second direction. The first direction is the arrangement direction of the low-pass filter circuit and the bandpass filter circuit, and the second direction intersects the first direction.

[0016] In this configuration, the first and second matching networks achieve impedance matching between the bandpass filter circuit and external devices, improving the high-frequency matching performance of the bandpass filter circuit. Furthermore, the bandpass filter circuit eliminates the need for additional matching circuits. Using smaller first and second matching networks can reduce the size of the bandpass filter circuit and minimize circuit losses associated with the matching circuits, ultimately achieving low insertion loss for the RF device.

[0017] In some embodiments, the low-pass filter circuit includes: a third resonant unit, a fourth resonant unit, a fifth resonant unit, a third inductor, a fourth inductor, and a fifth inductor. The first end of the third inductor is electrically connected to the input terminal, the second end of the third inductor is electrically connected to the first end of the fourth inductor, the second end of the fourth inductor is electrically connected to the first end of the fifth inductor, and the second end of the fifth inductor is electrically connected to the second output terminal. The third resonant unit is electrically connected to the second end of the third inductor, the fourth resonant unit is electrically connected to the second end of the fourth inductor, and the fifth resonant unit is electrically connected to the second end of the fifth inductor.

[0018] The third, fourth, and fifth inductors are sequentially connected in series between the input terminal and the second output terminal, generating a low-pass response when the low-pass filter circuit is operating, thereby suppressing high-frequency RF signals. Furthermore, the third, fourth, and fifth resonant units generate three out-of-band transmission zeros, suppressing second and third harmonics. This improves the accuracy of low-frequency RF signals filtered by the low-pass filter circuit, thereby enhancing the frequency selection accuracy of the RF device.

[0019] In some embodiments, the low-pass filter circuit and the band-pass filter circuit are arranged sequentially along a first direction, and the second direction intersects the first direction. The third inductor, the fourth inductor, and the fifth inductor are arranged sequentially along the second direction, and the fifth inductor and the fifth resonant unit are located on the same side of the fourth inductor.

[0020] With such an arrangement, when designing a low-pass filter circuit, the size of the low-pass filter circuit in the second direction can be adjusted by adjusting the layout positions of the third inductor, the fourth inductor, and the fifth inductor. This allows the size of the low-pass filter circuit in the first direction to be reduced while controlling the size of the low-pass filter circuit in the second direction, thereby improving the utilization rate of the substrate layout area.

[0021] Secondly, by arranging the fifth inductor and the fifth resonant unit on the same side of the fourth inductor, the area occupied by the entirety of the fifth inductor and the fifth resonant unit on the substrate can be reduced, further reducing the circuit size of the low-pass filter circuit, thereby achieving a miniaturized design of the radio frequency device.

[0022] In some embodiments, the fifth inductor includes a first sub-inductor and a second sub-inductor. The first sub-inductor extends along a first direction, with one end of the first sub-inductor connected to the second end of the fourth inductor. The second sub-inductor extends along a second direction, with one end of the second sub-inductor connected to the other end of the first sub-inductor, and the other end of the second sub-inductor connected to the second output terminal. The first sub-inductor and the second sub-inductor form a first region, and at least a portion of the fifth resonant unit is located within the first region.

[0023] This arrangement facilitates the first sub-inductor and the second sub-inductor to enclose a first region, thereby embedding at least a portion of the fifth resonant unit within the first region. This reduces the layout area occupied by the fifth inductor and the fifth resonant unit, improves substrate area utilization, and further reduces the circuit size of the low-pass filter circuit.

[0024] In some embodiments, the third inductor includes a third sub-inductor and a fourth sub-inductor. The third sub-inductor extends along the first direction, with one end of the third sub-inductor connected to the input terminal. The fourth sub-inductor extends along the second direction, with one end of the fourth sub-inductor connected to the other end of the third sub-inductor, and the other end of the fourth sub-inductor connected to the first end of the fourth inductor. The third sub-inductor, the fourth inductor, and the first sub-inductor are arranged sequentially along the first direction.

[0025] With this arrangement, the third sub-inductor provides space for combining the fourth inductor and the first inductor in the first direction, thereby shortening the distance between the fourth inductor and the first inductor, thereby reducing the layout area occupied by the combined fourth inductor and the first inductor, thereby improving the utilization rate of the substrate area.

[0026] In some embodiments, the fifth inductor, the third resonance unit, and the second resonance unit are sequentially arranged along the first direction.

[0027] Such a configuration can avoid an increase in the size of the low-pass filter circuit in the second direction, so that the size of the low-pass filter circuit in the second direction is adapted to the size of the band-pass filter circuit in the second direction, thereby avoiding an increase in the size of the entire RF device in the second direction.

[0028] In some embodiments, the first resonant unit and the second resonant unit are sequentially arranged along the second direction. The third inductor and the fourth inductor are located between the first resonant unit and the bandpass filter circuit.

[0029] Such an arrangement can shorten the overall size of the third resonant unit and the fourth resonant unit in the first direction, thereby reducing the size of the low-pass filter circuit in the first direction, and further reducing the size of the RF device, thereby achieving miniaturization and integrated design of the RF device.

[0030] In another aspect, a communication device is provided, comprising: the radio frequency device described above and a mainboard. The mainboard is connected to the radio frequency device. The communication device provided in the embodiment of the present application includes the radio frequency device described above, and thus has all the aforementioned beneficial effects, which are not further elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG1 is a schematic structural diagram of a communication device provided in some embodiments of the present application;

[0032] FIG2 is a structural block diagram of a filter provided in some embodiments of the present application;

[0033] FIG3 is a schematic structural diagram of a radio frequency device in a related art provided by some embodiments of the present application;

[0034] FIG4 is a schematic diagram of the structure of a filter in a related art provided by some embodiments of the present application;

[0035] FIG5 is a schematic structural diagram of a radio frequency device provided in some embodiments of the present application;

[0036] FIG6 is a circuit topology diagram of a radio frequency device provided in some embodiments of the present application;

[0037] FIG7 is a schematic structural diagram of another radio frequency device provided in some embodiments of the present application;

[0038] FIG8 is a circuit topology diagram of another radio frequency device provided in some embodiments of the present application;

[0039] FIG9 is a schematic structural diagram of another radio frequency device provided in some embodiments of the present application;

[0040] FIG10 is a test curve diagram of a bandpass filter circuit of a radio frequency device provided by some embodiments of the present application;

[0041] FIG11 is a test curve diagram of a low-pass filter circuit of a radio frequency device provided in some embodiments of the present application. DETAILED DESCRIPTION

[0042] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in some embodiments of the present application. Obviously, the embodiments described are only some embodiments of the present application, not all embodiments. Based on the embodiments provided in this application, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of this application.

[0043] In the following, the terms "first," "second," etc., are used for descriptive convenience only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Thus, a feature specified as "first," "second," etc. may explicitly or implicitly include one or more of such features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0044] Unless the context requires otherwise, throughout the specification and claims, the term "including" is to be interpreted as having an open, inclusive meaning, that is, "including, but not limited to." In the description of the specification, the terms "one embodiment," "some embodiments," "exemplary embodiments," "exemplarily," or "some examples" are intended to indicate that specific features, structures, materials, or characteristics associated with the embodiment or example are included in at least one embodiment or example of the present application. The schematic representations of the above terms do not necessarily refer to the same embodiment or example. In addition, the specific features, structures, materials, or characteristics may be included in any one or more embodiments or examples in any appropriate manner.

[0045] Exemplary embodiments are described herein with reference to cross-sectional and / or plan views that are idealized exemplary drawings. In the drawings, the thicknesses of layers and regions are exaggerated for clarity. Therefore, variations in shape relative to the drawings due to, for example, manufacturing techniques and / or tolerances are contemplated. Therefore, the exemplary embodiments should not be construed as limited to the shapes of the regions shown herein, but rather include deviations in shape due to, for example, manufacturing. For example, an etched region shown as a rectangle will typically have curved features. Therefore, the regions shown in the drawings are schematic in nature, and their shapes are not intended to illustrate the actual shape of regions of the device and are not intended to limit the scope of the exemplary embodiments.

[0046] In the embodiments of this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as "exemplary" or "for example" in the embodiments of this application should not be interpreted as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0047] FIG1 is a schematic structural diagram of a communication device 01 provided in an embodiment of the present application.

[0048] Please refer to Figure 1. An embodiment of the present application provides a communication device 01, which can be a terminal product such as a mobile phone, a tablet computer, or a drone; or, the communication device 01 can also be a communication device such as a base station, a routing device, a server, or a vehicle-mounted device.

[0049] As shown in FIG1 , the communication device 01 may include a mainboard 02 and a radio frequency device 03 , wherein the mainboard 02 and the radio frequency device 03 are electrically connected.

[0050] The motherboard 02 may include a circuit board, at least one memory device, and at least one processor disposed on the circuit board. The memory, which may also be referred to as a storage medium or storage device, is used to store software programs. The processor is used to read and execute the software programs in the memory. As a feasible implementation, the memory may be provided independently of the processor; as another feasible implementation, the memory may be integrated with the processor.

[0051] The RF device 03 can be installed on the mainboard 02 and connected to the processor on the mainboard 02. The RF device 03 is used to transmit and receive RF signals. RF (Radio Frequency, RF) signals include: electrical signals with a specific frequency. Generally, RF signals can include: received signals and transmitted signals. The received signal can be called R X (Receive) signal, the transmitted signal can be called T X (Transport) signal.

[0052] In the embodiment of the present application, the RF device 03 may be a duplexer. The duplexer has functions such as suppressing interference between adjacent channels and reducing the noise figure. The quality of its performance can directly affect the performance of the RF device 03 and even the entire communication device. Structurally, the duplexer is a three-port RF device composed of two filters. This allows the transceiver system to share a single antenna, thereby reducing device complexity and saving space. The filter, as the basic component of the duplexer, is a frequency-selective device. Therefore, each channel of the duplexer has a high frequency selectivity characteristic.

[0053] FIG2 is a structural block diagram of a filter 302 provided in some embodiments of the present application.

[0054] Referring to Figure 2 , filter 302 may include at least one first resonator 100A and at least one second resonator 100B. Filter 302 may also include an input port IN, an output port OUT, and a ground terminal. The at least one first resonator 100A may be electrically connected in series between the input port IN and the output port OUT, and the second resonator 100B may be electrically connected between the first resonator 100A and the ground terminal. By providing multiple first resonators 100A, filter 302 forms a first band-stop; by providing multiple second resonators 100B, filter 302 forms a second band-stop. This configuration allows filter 302 to have a corresponding passband, allowing signals in the corresponding frequency band to pass.

[0055] For example, the filter 302 shown in FIG. 2 may include three first resonators 100A and two second resonators 100B. Of course, in other embodiments, the number of first resonators 100A and second resonators 100B in the filter 302 may be set accordingly according to actual needs.

[0056] FIG3 is a schematic diagram of the structure of a radio frequency device 03 in a related technology provided in some embodiments of the present application, and FIG4 is a schematic diagram of the structure of a filter 302 in a related technology provided in some embodiments of the present application.

[0057] In related art, referring to Figures 3 and 4, slots 203 are formed in the ground conductor of the first layer 201, creating two filters 302, thereby forming a duplexer with a stepped impedance resonator. Furthermore, a T-shaped microstrip line and a straight microstrip line are designed in the second layer 202, with the T-shaped microstrip line serving as a shared input port and the straight microstrip lines serving as output ports for the upper and lower layers. A slotted duplexer can feed signal energy into the ports through vertical coupling, but this coupling method results in high insertion loss and a large overall size for the resulting RF device.

[0058] FIG5 is a schematic structural diagram of a radio frequency device 03 provided in some embodiments of the present application.

[0059] Referring to FIG. 5 , in some embodiments, the RF device 03 includes a substrate 33 and a bandpass filter circuit 310, a lowpass filter circuit 320, an input terminal CP, a first output terminal HP, and a second output terminal LP disposed on the substrate 33. The lowpass filter circuit 320 is electrically connected between the input terminal and the second output terminal. The bandpass filter circuit 310 includes a first resonant unit 311, a second resonant unit 312, and a first capacitor C1. The first resonant unit 311 includes a second capacitor C2 and a first inductor L1. The first end of the second capacitor C2 is electrically connected to the input terminal CP, and the second end of the second capacitor C2 is electrically connected to the first end of the first inductor L1. The second resonant unit 312 includes a third capacitor C3 and a second inductor L2. The first end of the third capacitor C3 is electrically connected to the first output terminal HP, and the second end of the third capacitor C3 is electrically connected to the first end of the second inductor L2. The second end of the second inductor L2 is electrically connected to the second end of the first inductor L1. The first capacitor C1 is electrically connected between the second end of the second capacitor C2 and the second end of the third capacitor C3.

[0060] In some examples, the RF device 03 may be, but is not limited to, a duplexer, a RF module, or other circuit components in a RF circuit.

[0061] 5 , the radio frequency device 03 may be a three-terminal device including an input terminal CP, a first output terminal HP, and a second output terminal LP.

[0062] When the RF device 03 is in operation, it receives RF signals via the input terminal CP. When the received RF signals pass through the low-pass filter circuit 320, RF signals above the low-pass target frequency are suppressed by the low-pass filter circuit 320. The RF signals that meet the low-pass target frequency obtained after filtering pass through the low-pass filter circuit 320 and are transmitted to the subsequently connected RF circuit via the second output terminal LP.

[0063] On one side of the bandpass filter circuit 310, when the RF signal passes through the bandpass filter circuit 310, the RF signals outside the bandpass target frequency band are suppressed by the bandpass filter circuit 310, and the RF signals within the bandpass target frequency band obtained after filtering can pass through the bandpass filter circuit 310 and be transmitted to the subsequently connected RF circuit via the first output terminal HP.

[0064] In other embodiments, the input terminal CP receives a radio frequency signal from an antenna, that is, the antenna is connected to the duplexer through the input terminal CP, wherein the antenna can send wireless signals of different frequencies to other communication devices, or receive wireless signals from other communication devices. Therefore, the radio frequency device 03 of the embodiment of the present application can be used in the transmission frequency band, or in the reception frequency band. The radio frequency device 03 can suppress various frequencies in the reception frequency band or the transmission frequency band, that is, filter the radio frequency signals in the reception frequency band or the transmission frequency band.

[0065] The target frequency bands of the low-pass filter circuit 320 and the band-pass filter circuit 310 can be set as needed.

[0066] FIG6 is a circuit topology diagram of a radio frequency device 03 provided in some embodiments of the present application.

[0067] Referring to Figure 6, in some embodiments, the topology of the bandpass filter circuit 310 includes: a first capacitor C1, a second capacitor C2, a third capacitor C3, a first inductor L1, and a second inductor L2. For example, the second capacitor C2 and the first inductor L1 form a first resonant unit 311, with the second end of the first inductor L1 being grounded; the third capacitor C3 and the second inductor L2 form a second resonant unit 312, with the second end of the second inductor L2 being grounded. The first inductor L1 and the second inductor L2 are connected in series with the first capacitor C1. In this case, the parallel resonance of the first capacitor C1 can generate a transmission zero, thereby suppressing high-frequency harmonics.

[0068] Secondly, when bandpass filter circuit 310 is operating, first resonant unit 311 and second resonant unit 312 form a second-order bandpass filter passband. The filter response generated by the circuit has two additional transmission zeros: the first transmission zero is controlled by second capacitor C2 and first inductor L1, and the second transmission zero is controlled by third capacitor C3 and second inductor L2. By generating three transmission zeros, bandpass filter circuit 310 can effectively suppress RF signals outside the target frequency band, thereby improving the out-of-band suppression capability of bandpass filter circuit 310 and, in turn, the out-of-band suppression capability of the entire RF device 03.

[0069] In some examples, a microstrip line structure can be formed by soldering strip conductors onto substrate 33 in the manner of a printed circuit board. The strip conductors can include metal transmission lines, etc. In the embodiments of the present application, RF device 03 can adopt the above-mentioned microstrip line structure. Such a configuration can reduce the production cost of RF device 03.

[0070] For example, the first capacitor C1, the second capacitor C2, and the third capacitor C3 can all be planar interdigital capacitors, and the first inductor L1 and the second inductor L2 can both be planar kinked inductors. The interdigital capacitors are capacitors constructed using microstrip lines, and the kinked inductors are inductors formed by bending high-impedance metal lines. The high-impedance metal lines have narrow line widths, which can improve inductor frequency band selectivity while reducing impedance loss.

[0071] At the same time, the use of interdigital capacitors and zigzag inductors to design the circuit structure of the bandpass filter circuit 310 can greatly reduce the size of the bandpass filter circuit 310, thereby reducing the circuit size of the radio frequency device 03.

[0072] 5 , in some embodiments, the low-pass filter circuit 320 and the band-pass filter circuit 310 are sequentially arranged along a first direction Y, and the second direction X intersects the first direction Y. The second capacitor C2 , the first capacitor C1 , and the third capacitor C3 are sequentially arranged along the second direction X.

[0073] In some examples, the first direction Y can be perpendicular to the second direction X.

[0074] In other examples, the angle between the first direction Y and the second direction X may be 30°, 45°, or 60°, etc.

[0075] Exemplarily, a planar interdigitated capacitor is composed of two parallel electrodes and a rectangular interdigital finger located between the two electrodes. In the circuit layout design of the embodiment of the present application, the second capacitor C2, the first capacitor C1, and the third capacitor C3 are arranged in sequence along the second direction X, and two adjacent capacitors share the same electrode. For example, the electrode of the first capacitor C1 close to the output terminal CP is used as the electrode of the second capacitor C2. For another example, the electrode of the first capacitor C1 far from the output terminal CP is used as the electrode of the third capacitor C3.

[0076] This arrangement helps reduce the number of electrodes, thereby shortening the spacing between the second capacitor C2, the first capacitor C1, and the third capacitor C3. This reduces the width of the bandpass filter circuit 310 in the second direction X, further reducing the size of the RF device 03 in the second direction X, thereby achieving miniaturization and integration of the RF device 03. Furthermore, the second capacitor C2, the first capacitor C1, and the third capacitor C3 serve as the main structure of the bandpass filter circuit 310. By arranging the layout positions of the second capacitor C2, the first capacitor C1, and the third capacitor C3, the overall layout position of the bandpass filter circuit 310 on the substrate 33 can be controlled, facilitating the miniaturization of the circuit structure of the RF device 03.

[0077] Continuing to refer to FIG. 5 , in some embodiments, the first inductor L1 and the second inductor L2 are located on a side of the first capacitor C1 close to the low-pass filter circuit 320 .

[0078] In some examples, by placing the overall layout consisting of the second capacitor C2, the first capacitor C1, and the third capacitor C3 connected in series on a side away from the low-pass filter circuit 320, the edge shape of the RF device 03 can be regularized, thereby avoiding waste of layout area due to the irregular shapes of the first inductor L1 and the second inductor L2, or avoiding an increase in the size of the entire RF device 03 due to the irregular shapes of the first inductor L1 and the second inductor L2.

[0079] With this arrangement, the low-pass filter circuit 320 designed later can be used to perform layout splicing with the first inductor L1 and the second inductor L2, thereby shortening the distance between the internal circuit structures of the RF device 03, thereby reducing the size of the circuit structure of the RF device 03 and realizing a miniaturized design of the RF device 03.

[0080] Of course, in other embodiments, the first inductor L1 and the second inductor L2 may be located on a side of the first capacitor C1 away from the low-pass filter circuit 320 .

[0081] In other examples, referring to the structural diagram shown in FIG5 , the first resonant unit 311 and the second resonant unit 312 are symmetrically distributed. Therefore, the first inductor L1 and the second inductor L2 inside the two resonant units are also symmetrically designed in structure. The first inductor L1 is taken as an example for introduction below.

[0082] The first inductor L1 includes a fifth sub-inductor L11 and a sixth sub-inductor L12. The first end of the fifth sub-inductor L11 is electrically connected to the second end of the second capacitor C2, the second end of the fifth sub-inductor L11 is connected to the first end of the sixth sub-inductor L12, and the second end of the sixth sub-inductor L12 is grounded. The fifth sub-inductor L11 and the sixth sub-inductor L12 can both be metal wires, with the fifth sub-inductor L11 extending along the second direction X, and the sixth sub-inductor L12 extending along the first direction Y. By arranging the layout positions of the fifth sub-inductor L11 and the sixth sub-inductor L12, the first inductor L1 can be bent, thereby adapting it to the size of the first capacitor C1 in the second direction X and reducing the size of the first inductor L1 in the second direction X. This helps reduce the size of the bandpass filter circuit 310 and achieves a miniaturized and integrated design of the RF device 03.

[0083] Since the first inductor L1 and the second inductor L2 are symmetrical in structure, the second inductor L2 will not be described in detail here. The symmetrical layout of the bandpass filter circuit 310 can regularize the layout of the circuit, facilitate the layout of the subsequent circuit structure on the substrate 33, thereby improving the utilization rate of the substrate 33 area and facilitating the rational planning of the layout to achieve a miniaturized design.

[0084] FIG7 is a schematic structural diagram of another radio frequency device 03 provided in some embodiments of the present application.

[0085] Referring to FIG. 7 , in some embodiments, the bandpass filter circuit 310 further includes a first matching network 313 and a second matching network 314. The first matching network 313 is electrically connected between the input terminal CP and the first end of the second capacitor C2, and the second matching network 314 is electrically connected between the second end of the third capacitor C3 and the first output terminal HP. The first matching network 313 and the second matching network 314 each include a rectangular conductive block. The first direction Y represents the arrangement direction of the bandpass filter circuit 310 and the low-pass filter circuit 320, and the second direction X intersects the first direction Y.

[0086] In some examples, a first matching network 313 and a second matching network 314 are respectively provided at the input terminal CP and the first output terminal HP as transition structures connecting the bandpass filter circuit 310 with external devices, thereby achieving impedance matching between the bandpass filter circuit 310 and the external devices. The external devices may include: antennas, coplanar waveguides, or other radio frequency circuits. For example, the impedance of the antenna connected to the input terminal is Z1, and the internal impedance of the bandpass filter circuit 310 is Z2. Then, the impedance Z3 of the first matching network 313 satisfies the following impedance matching formula when designed: Z3 2 =Z1Z2. The design principle of the impedance matching of the second matching network 314 is the same as that of the first matching network 313, which will not be described in detail.

[0087] By providing the first matching network 313 and the second matching network 314, impedance matching between the input terminal CP and the first output terminal HP and the external circuit can be achieved, thereby reducing signal reflections that occur when the RF signal enters or outputs the bandpass filter circuit 310, thereby reducing the attenuation of the RF signal and improving the high-frequency matching performance of the bandpass filter circuit 310.

[0088] Exemplarily, the first matching network 313 and the second matching network 314 can be rectangular metal blocks. The first matching network 313 extends along the second direction X, with its width w1 in the first direction Y being smaller than its width l1 in the second direction X. The second matching network 314 extends along the first direction Y, with its width l2 in the first direction Y being larger than its width w2 in the second direction X. When the bandpass filter circuit 310 is operating, by adjusting the length and width of the first matching network 313 and the second matching network 314, the impedance matching performance between the input terminal CP and the first output terminal HP of the RF device 03 and external devices can be adjusted, thereby improving the impedance matching performance of the RF device 03.

[0089] With this configuration, the bandpass filter circuit 310 eliminates the need for a separate matching circuit. The matching circuit occupies a larger area on the substrate 33 than the matching network. For example, the matching circuit can be composed of concentrated components such as inductors and capacitors. Therefore, the use of the first matching network 313 and the second matching network 314 can reduce the area occupied by the bandpass filter circuit 310 on the substrate 33, thereby achieving a miniaturized and integrated design for the RF device 03. Furthermore, eliminating the matching circuit can avoid losses incurred by the matching circuit, thereby reducing losses in the bandpass filter circuit 310.

[0090] Continuing with FIG. 7 , in some embodiments, the low-pass filter circuit 320 includes a third resonant unit 321, a fourth resonant unit 322, a fifth resonant unit 323, a third inductor L3, a fourth inductor L4, and a fifth inductor L5. A first end of the third inductor L3 is electrically connected to the input terminal CP, and a second end of the third inductor L3 is electrically connected to a first end of the fourth inductor L4. A second end of the fourth inductor L4 is electrically connected to a first end of the fifth inductor L5, and a second end of the fifth inductor L5 is electrically connected to the second output terminal LP. The third resonant unit 321 is electrically connected to a second end of the third inductor L3, the fourth resonant unit 322 is electrically connected to a second end of the fourth inductor L4, and the fifth resonant unit 323 is electrically connected to a second end of the fifth inductor L5.

[0091] FIG8 is a circuit topology diagram of another radio frequency device 03 provided in some embodiments of the present application.

[0092] In some examples, referring to FIG. 8 , the third inductor L3 , the fourth inductor L4 , and the fifth inductor L5 of the low-pass filter circuit 320 are sequentially connected in series between the input terminal CP and the second output terminal LP. When the low-pass filter circuit 320 is operating, a low-pass response can be generated, thereby suppressing RF signals in the high-frequency band.

[0093] In addition, the third resonant unit 321, the fourth resonant unit 322 and the fifth resonant unit 323 are all LC series grounded resonators. When the low-pass filter circuit 320 is working, the second harmonic and the third harmonic can be suppressed, thereby improving the accuracy of the low-frequency band RF signal filtered by the low-pass filter circuit 320.

[0094] Continuing with FIG8 , the third resonant unit 321 includes a fourth capacitor C4 and a sixth inductor L6. The first end of the fourth capacitor C4 is electrically connected to the second end of the third inductor L3, the second end of the fourth capacitor C4 is connected to the first end of the sixth inductor L6, and the second end of the sixth inductor L6 is grounded. The fourth resonant unit 322 includes a fifth capacitor C5 and a seventh inductor L7. The first end of the fifth capacitor C5 is electrically connected to the second end of the fourth inductor L4, the second end of the fifth capacitor C5 is connected to the first end of the seventh inductor L7, and the second end of the seventh inductor L7 is grounded. The fifth resonant unit 323 includes a sixth capacitor C6 and an eighth inductor L8. The first end of the sixth capacitor C6 is electrically connected to the second end of the fifth inductor L5, the second end of the sixth capacitor C6 is connected to the first end of the eighth inductor L8, and the second end of the eighth inductor L8 is grounded.

[0095] By providing the third resonant unit 321, the fourth resonant unit 322, and the fifth resonant unit 323, when the low-pass filter circuit 320 is in operation, the generated filtering response has three out-of-band transmission zeros, namely, the fourth transmission zero controlled by the fourth capacitor C4 and the sixth inductor L6, the fifth transmission zero controlled by the fifth capacitor C5 and the seventh inductor L7, and the sixth transmission zero controlled by the sixth capacitor C6 and the eighth inductor L8. As a result, the low-pass filter circuit 320 has a strong suppression capability for the second harmonic and the third harmonic, which is beneficial to improving the accuracy of the frequency selection of the radio frequency device 03.

[0096] The fourth capacitor C4, fifth capacitor C5, and sixth capacitor C6 of the low-pass filter circuit 320 can all be planar interdigital capacitors, and the third inductor L3, fourth inductor L4, fifth inductor L5, sixth inductor L6, seventh inductor L7, and eighth inductor L8 can all be planar zigzag inductors. By designing the low-pass filter circuit 320 with a microstrip structure, the production cost of the low-pass filter circuit 320 can be reduced. Furthermore, the use of interdigital capacitors and zigzag inductors in designing the circuit structure of the low-pass filter circuit 320 can significantly reduce the area occupied by the circuit on the substrate 33, thereby reducing the circuit size of the RF device 03.

[0097] In some embodiments, the low-pass filter circuit 320 and the band-pass filter circuit 310 are arranged sequentially along a first direction Y, and the second direction X intersects the first direction Y. The third inductor L3, the fourth inductor L4, and the fifth inductor L5 are arranged sequentially along the second direction X, and the fifth inductor L5 and the fifth resonant unit 323 are located on the same side of the fourth inductor L4.

[0098] Continuing with FIG. 7 , in the circuit layout design, since the third inductor L3, the fourth inductor L4, and the fifth inductor L5 are all formed by bending high-impedance metal wires, the third inductor L3, the fourth inductor L4, and the fifth inductor L5 are sequentially arranged along the second direction X. This can shorten the size of the low-pass filter circuit 320 in the second direction X, thereby reducing the circuit size of the RF device 03 in the second direction X and improving the area utilization of the RF device's substrate 33.

[0099] Furthermore, the degree of bending of the third inductor L3, the fourth inductor L4, and the fifth inductor L5 can be adjusted based on the circuit function or circuit layout design requirements. For example, the degree of bending of the third inductor L3, the fourth inductor L4, and the fifth inductor L5 can be adjusted based on the layout positions of the first inductor L1 and the second inductor L2, thereby shortening the distance between the entire structure formed by the third inductor L3, the fourth inductor L4, and the fifth inductor L5 and the first inductor L1 and the second inductor L2. This improves the area utilization of the substrate 33, reduces the circuit size of the RF device 03, and further achieves a miniaturized design.

[0100] Secondly, in the circuit layout design, by arranging the fifth inductor L5 and the fifth resonant unit 323 on the same side of the fourth inductor L4, the area occupied by the entirety of the fifth inductor L5 and the fifth resonant unit 323 on the substrate 33 can be reduced. The specific layout position can be achieved by adjusting the degree of bending of the fifth inductor L5 and the eighth inductor L8 within the fifth resonant unit 323.

[0101] In some embodiments, the fifth inductor L5 includes a first sub-inductor L51 and a second sub-inductor L52. The first sub-inductor L51 extends along a first direction Y, with one end of the first sub-inductor L51 connected to the second end of the fourth inductor L4. The second sub-inductor L52 extends along a second direction X, with one end of the second sub-inductor L52 connected to the other end of the first sub-inductor L51, and the other end of the second sub-inductor L52 connected to the second output terminal LP. The first sub-inductor L51 and the second sub-inductor L52 form a first region A, and at least a portion of the fifth resonant unit 323 is located within the first region A.

[0102] Continuing with FIG. 7 , in the circuit layout design, the first sub-inductor L51 and the second sub-inductor L52 of the fifth inductor L5 can enclose a first area A. This arrangement allows at least a portion of the fifth resonant unit 323 to be embedded within the first area A, thereby reducing the size in the first direction Y and the layout area occupied by the combined fifth inductor L5 and the fifth resonant unit 323 . This, in turn, improves the utilization of the substrate 33 area, reduces circuit size, and facilitates the miniaturization of the RF device 03 .

[0103] In some embodiments, the third inductor L3 includes a third sub-inductor L31 and a fourth sub-inductor L32. The third sub-inductor L31 extends along the first direction Y, with one end of the third sub-inductor L31 connected to the input terminal CP. The fourth sub-inductor L32 extends along the second direction X, with one end of the fourth sub-inductor L32 connected to the other end of the third sub-inductor L31, and the other end of the fourth sub-inductor L32 connected to the first end of the fourth inductor L4. The third sub-inductor L31, the fourth inductor L4, and the first sub-inductor L51 are arranged sequentially along the first direction Y.

[0104] Continuing with FIG. 7 , illustratively, in the circuit layout design, the third inductor L3 is bent into an L-shape, and the sum of the widths of the fourth inductor L4 and the first inductor L1 in the first direction Y is less than or equal to the length of the third sub-inductor L31 extending in the first direction Y. This facilitates providing space for layout splicing of the fourth inductor L4 and the first inductor L1 in the first direction Y.

[0105] In some examples, the fourth inductor L4 employs a serpentine bend, with the first end of the fourth inductor L4 serving as the starting point of the serpentine bend. Starting from the starting end of the fourth inductor L4 and extending along the first direction Y, the width of the structure formed after three bends in the first direction Y is greater than the width of the structure formed by subsequent bends in the first direction Y. This arrangement facilitates shortening the distance between the fourth inductor L4 and the first inductor L1 when they are combined in the first direction Y, thereby reducing the layout area occupied by the combined fourth inductor L4 and first inductor L1, thereby improving the utilization of the substrate 33 area.

[0106] In some embodiments, the fifth inductor L5 , the fifth resonance unit 323 , and the fourth resonance unit 322 are sequentially arranged along the first direction Y.

[0107] 7 , in some examples, the fifth resonant unit 323 is disposed in the first area A, so that the entirety of the fifth resonant unit 323 and the third and fourth inductors L3 and L4 are disposed along the second direction X, thereby limiting the size of the low-pass filter circuit 320 in the second direction X.

[0108] By arranging the fourth resonant unit 322, the fifth inductor L5, and the fifth resonant unit 323 in sequence along the first direction Y, further increase in the size of the low-pass filter circuit 320 in the second direction X can be avoided. As a result, the size of the low-pass filter circuit 320 in the second direction X is adapted to the size of the band-pass filter circuit 310 in the second direction X, thereby avoiding an increase in the overall size of the RF device 03 in the second direction X, which is conducive to the miniaturization design of the RF device 03.

[0109] In some embodiments, the third resonant unit 321 and the fourth resonant unit 322 are sequentially arranged along the second direction X. The third inductor L3 and the fourth inductor L4 are located between the third resonant unit 321 and the bandpass filter circuit 310 .

[0110] Continuing with FIG. 7 , in some examples, the third inductor L3, the fourth inductor L4, and the fifth inductor L5 of the low-pass filter circuit 320 are sequentially connected in series between the input terminal CP and the second output terminal LP, thereby defining the dimensions of the low-pass filter circuit 320 in the second direction X. By sequentially arranging the third resonant unit 321 and the fourth resonant unit 322 along the second direction X, the overall dimensions of the third resonant unit 321 and the fourth resonant unit 322 in the first direction Y can be shortened, thereby reducing the area occupied by the entire low-pass filter circuit 320 on the substrate 33 and improving the utilization of the layout area of ​​the substrate 33.

[0111] In other examples, the third resonant unit 321 can be an LC series resonant unit. By adjusting the bending degree of the sixth inductor L6 inside the third resonant unit 321, the fourth capacitor C4 and the sixth inductor L6 can also be arranged in sequence along the second direction X, thereby shortening the length of the third resonant unit 321 in the first direction Y, thereby further reducing the layout area occupied by the low-pass filter circuit 320 on the substrate 33, which is conducive to further miniaturization of the radio frequency device 03.

[0112] The following describes the size parameters and finished product testing of the radio frequency device 03 using a specific embodiment.

[0113] FIG9 is a schematic structural diagram of another radio frequency device 03 provided in some embodiments of the present application. To facilitate analysis and introduction of the performance of the radio frequency device 03, the parameter settings in this embodiment are merely schematic settings, and the embodiments of the present application do not limit specific parameters.

[0114] Please refer to Figure 9. In the embodiment of the present application, the dimensional parameters of the substrate 33 are m=9.1mm and n=8.1mm, wherein a grounding structure 34 may be further provided on the periphery of the circuit structure of the radio frequency device 03, thereby protecting the internal circuit structure of the radio frequency device 03 and achieving isolation from other devices in the communication device 01. For example, the grounding structure 34 may adopt a microstrip line structure, wherein a break exists on one side of the grounding structure 34 close to the input terminal CP, for providing a channel for connecting an external device to the input terminal CP. Similarly, a break exists on both sides of the grounding structure 34 close to the first output terminal HP and the second output terminal LP, for providing a channel for connecting the first output terminal HP and the second output terminal LP to the external circuit respectively.

[0115] In the bandpass filter circuit 310, the circuit is designed to have a high-frequency passband of 5.15 GHz to 5.85 GHz. For example, in the bandpass filter circuit 310, the dimensions of the first matching network 313 connected to the input terminal CP are l1 = 2 mm and w1 = 1.07 mm; the dimensions of the second matching network 314 connected to the first output terminal HP are l2 = 2.95 mm and w2 = 0.75 mm; the finger length a1 of the first capacitor C1 is 0.8 mm, the finger width b1 is 0.15 mm, and the finger spacing c1 is 0.2 mm; the finger length a2 of the second capacitor C2 within the first resonant unit 311 is 0.9 mm, the finger width b2 is 0.15 mm, and the finger spacing c2 is 0.125 mm; and the total length l3 of the first inductor L1 is 2.875 mm. Since the second resonant unit 312 and the first resonant unit 311 are symmetrically arranged, the third capacitor C3 and the second inductor L2 in the second resonant unit 312 have the same size, which will not be described in detail here.

[0116] In the low-pass filter circuit 320, the circuit is designed with a low-frequency passband of 2.4 GHz to 2.5 GHz. For example, in the low-pass filter circuit 320, the total length l4 of the third inductor L3 is 5.95 mm, the total length l5 of the fourth inductor L4 is 11.65 mm, and the total length l6 of the fifth inductor L5 is 3.36 mm. By properly bending the inductors, the circuit size can be reduced. The total length of the sixth inductor inside the third resonant unit 321 is l7 = 6.85 mm, the finger length a3 of the fourth capacitor is 1.9 mm, the finger width b3 is 0.25 mm, and the finger spacing c3 between two fingers is 0.15 mm; the total length of the seventh inductor inside the fourth resonant unit 322 is l8 = 1 mm, the finger length a4 of the fifth capacitor is 2.9 mm, the finger width b4 is 0.25 mm, and the finger spacing c4 between two fingers is 0.15 mm; the total length of the eighth inductor inside the fifth resonant unit 323 is l9 = 2.9 mm, the finger length a5 of the sixth capacitor is 0.88 mm, the finger width b5 is 0.35 mm, and the finger spacing c5 between two fingers is 0.1 mm.

[0117] When the RF device 03 is operating, the RF signal received at the input terminal CP passes through the bandpass filter circuit 310. Signals within the 2.4 GHz to 2.5 GHz and 10 GHz to 12 GHz frequency bands are suppressed by the first resonant unit 311 and the second resonant unit 312 within the bandpass filter circuit 310. Second harmonic signals within the 10 GHz to 15 GHz frequency band are suppressed by the parallel resonance generated by the first capacitor C1 within the bandpass filter circuit 310. Ultimately, the RF signal within the 5.15 GHz to 5.85 GHz frequency band passes through and is transmitted to a subsequently electrically connected RF circuit via the first output terminal HP.

[0118] When passing through the low-pass filter circuit 320, the third inductor L3, the fourth inductor L4, and the fifth inductor L5 connected in series can generate a low-pass response, thereby allowing low-frequency signals in the frequency band of 2.4 GHz to 2.5 GHz to pass through and suppressing other signals above this frequency band. The series resonance generated by the third resonant unit 321, the fourth resonant unit 322, and the fifth resonant unit 323 within the low-pass filter circuit 320 further suppresses signals in the RF signal with the same resonant frequency, thereby improving the accuracy of the low-frequency signal output by the low-pass filter circuit 320 and its correspondence with the target frequency band, improving the in-band matching and out-of-band suppression capabilities of the RF device 03, and thus reducing the insertion loss of the RF device 03.

[0119] In some other examples, the target frequency bands allowed to pass by the band-pass filter circuit 310 and the low-pass filter circuit 320 can be changed as needed, and the design parameters of the circuit components can be adjusted accordingly.

[0120] FIG10 is a test curve diagram of the bandpass filter circuit 310 in the radio frequency device 03 provided in some embodiments of the present application.

[0121] Please refer to Figure 10, which shows a test curve chart of the bandpass filter circuit 310 within the RF device 03. The horizontal axis represents frequency, and the vertical axis represents gain. The test curve chart has six marked points. The performance of the bandpass filter circuit 310 of the RF device 03 is analyzed based on the values ​​of these six points. Marked points 3 and 4 are in-band points, while marked points 1-2 and 5-6 are out-of-band points. Test result S13 represents insertion loss.

[0122] For example, Marker 1 corresponds to a frequency of 2.4 GHz, Marker 2 corresponds to a frequency of 2.5 GHz, Marker 3 corresponds to a frequency of 5.15 GHz, Marker 4 corresponds to a frequency of 5.85 GHz, Marker 5 corresponds to a frequency of 10 GHz, and Marker 6 corresponds to a frequency of 12 GHz. By testing the parameter values ​​of S13 corresponding to Marker 1 through Marker 6 shown in the curve diagram, it can be analyzed that, when the bandpass filter circuit 310 of the RF device 03 of the present embodiment is operating, the insertion loss at Marker 3-4, which is within the band, is low; while the insertion loss corresponding to Marker 1-2 and Marker 5-6, which are outside the band, is high.

[0123] From this, it can be concluded that in bandpass filter circuit 310, the insertion loss of the marked points within the target bandpass frequency band is low, while the insertion loss of the marked points outside the target bandpass frequency band is high. In other words, bandpass filter circuit 310 has good in-band matching performance, with low attenuation of RF signals within the target bandpass frequency band. In addition, it has strong suppression capabilities for out-of-band signals. In other words, bandpass filter circuit 310 has strong in-band matching capabilities and out-of-band suppression capabilities.

[0124] FIG11 is a test curve diagram of the low-pass filter circuit 320 in the radio frequency device 03 provided in some embodiments of the present application.

[0125] Please refer to Figure 11, which shows a test curve chart of low-pass filter circuit 320 within RF device 03. The horizontal axis represents frequency, and the vertical axis represents gain. Four points are marked on this test curve chart. The performance of RF device 03 is analyzed based on the values ​​of these four points. Points 1 and 2 are in-band, while points 3 and 4 are out-of-band. Test result S21 represents insertion loss.

[0126] For example, Marker 1 corresponds to a frequency of 2.4 GHz, Marker 2 corresponds to a frequency of 2.5 GHz, Marker 3 corresponds to a frequency of 4.8 GHz, and Marker 4 corresponds to a frequency of 5.58 GHz. By testing the S21 parameter values ​​corresponding to Marker 1-Marker 4 shown in the curve diagram, it can be analyzed that when the low-pass filter circuit 320 of the RF device 03 of the embodiment of the present application is operating, the insertion loss of Marker 1-2, which is within the band, is low; while the insertion loss corresponding to Marker 3-4, which is outside the band, is high.

[0127] From this, we can conclude that in low-pass filter circuit 320, the insertion loss at the marker points within the low-pass target frequency band is low, while the insertion loss at the marker points outside the low-pass target frequency band is high. In other words, low-pass filter circuit 320 has excellent in-band matching performance, resulting in low attenuation of RF signals within the low-pass target frequency band. Furthermore, it has strong suppression capabilities for out-of-band signals. In other words, RF device 03 has strong in-band matching and out-of-band suppression capabilities.

[0128] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A radio frequency device, characterized in that, Comprising: a substrate, and a band-pass filter circuit, a low-pass filter circuit, an input end, a first output end, and a second output end provided on the substrate; the low-pass filter circuit is electrically connected between the input end and the second output end; the band-pass filter circuit includes: a first resonant unit, a second resonant unit, and a first capacitor; the first resonant unit includes a second capacitor and a first inductor, a first end of the second capacitor is electrically connected to the input end, and a second end of the second capacitor is electrically connected to a first end of the first inductor; the second resonant unit includes a third capacitor and a second inductor, a first end of the third capacitor is electrically connected to the first output end, and a second end of the third capacitor is electrically connected to a first end of the second inductor, wherein a second end of the second inductor is electrically connected to a second end of the first inductor; wherein, the first capacitor is electrically connected between the second end of the second capacitor and the second end of the third capacitor.

2. The radio frequency device according to claim 1, wherein the low-pass filter circuit and the band-pass filter circuit are arranged in sequence along a first direction, and a second direction intersects with the first direction; the second capacitor, the first capacitor, and the third capacitor are arranged in sequence along the second direction.

3. The radio frequency device according to claim 1 or 2, wherein the first inductor and the second inductor are located on a side of the first capacitor close to the low-pass filter circuit.

4. The radio frequency device according to any one of claims 1 to 3, characterized in that The band-pass filter circuit further includes: a first matching network and a second matching network; the first matching network is electrically connected between the input end and the first end of the second capacitor, and the second matching network is electrically connected between the second end of the third capacitor and the first output end, wherein both the first matching network and the second matching network include rectangular conductor blocks, and a width of the first matching network in the first direction is less than a width in the second direction, and a width of the second matching network in the first direction is greater than a width in the second direction; wherein, the first direction is the arrangement direction of the low-pass filter circuit and the band-pass filter circuit, and the second direction intersects with the first direction.

5. The radio frequency device according to any one of claims 1-4, characterized in that, The low-pass filter circuit includes: a third resonant unit, a fourth resonant unit, a fifth resonant unit, a third inductor, a fourth inductor, and a fifth inductor; a first end of the third inductor is electrically connected to the input end, a second end of the third inductor is electrically connected to a first end of the fourth inductor, a second end of the fourth inductor is electrically connected to a first end of the fifth inductor, and a second end of the fifth inductor is electrically connected to the second output end; the third resonant unit is electrically connected to the second end of the third inductor, the fourth resonant unit is electrically connected to the second end of the fourth inductor, and the fifth resonant unit is electrically connected to the second end of the fifth inductor.

6. The radio frequency device according to claim 5, wherein the low-pass filter circuit and the band-pass filter circuit are arranged in sequence along a first direction, and a second direction intersects with the first direction; The third inductor, the fourth inductor, and the fifth inductor are arranged in sequence along the second direction, and the fifth inductor and the fifth resonant unit are located on the same side of the fourth inductor.

7. The radio frequency device according to claim 6, wherein the fifth inductor includes a first sub-inductor and a second sub-inductor. The first sub-inductor extends along the first direction, and one end of the first sub-inductor is connected to the second end of the fourth inductor. The second sub-inductor extends along the second direction, one end of the second sub-inductor is connected to the other end of the first sub-inductor, and the other end of the second sub-inductor is connected to the second output end. Wherein, the first sub-inductor and the second sub-inductor enclose a first region, and at least a part of the third resonant unit is located in the first region.

8. The radio frequency device according to claim 7, wherein the third inductor includes a third sub-inductor and a fourth sub-inductor. The third sub-inductor extends along the first direction, and one end of the third sub-inductor is connected to the input end. The fourth sub-inductor extends along the second direction, one end of the fourth sub-inductor is connected to the other end of the third sub-inductor, and the other end of the fourth sub-inductor is connected to the first end of the fourth inductor. Wherein, the third sub-inductor, the fourth inductor, and the first sub-inductor are arranged in sequence along the first direction.

9. The radio frequency device according to any one of claims 6-8, wherein the fifth inductor, the third resonant unit, and the second resonant unit are arranged in sequence along the first direction.

10. The radio frequency device according to claim 8, wherein the first resonant unit and the second resonant unit are arranged in sequence along the second direction. The third inductor and the fourth inductor are located between the first resonant unit and the band-pass filter circuit.

11. A communication device, characterized in that, Comprising: a main board and the radio frequency device according to any one of claims 1-10. The main board is connected to the radio frequency device.

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