DC signal extraction structure and filter

Abstract

The invention provides a DC signal extraction structure and a filter, the DC signal extraction structure is used for being electrically connected with an input and / or output port of a radio frequency device, the port is an inductive transmission port, and the inductive transmission port comprises a transmission conductor. The DC signal extraction structure comprises a printed board, and an LC oscillation circuit, a main transmission circuit and a coupling structure which are arranged on the printed board. The transmission conductor is in coupling connection with the main transmission circuit through the coupling structure so as to convert the inductive transmission port into a capacitive transmission port; the LC oscillation circuit is connected with the transmission conductor so as to select frequency and extract DC signals of the radio frequency device. Capacitive coupling is achieved through the transmission conductor and the coupling structure so as to block the direct current signals, and the direct current signals of the corresponding frequency band are screened out from the direct current signals through the LC oscillation circuit so as to achieve the corresponding electrical performance.

Description

Technical Field

[0001] The invention belongs to the field of mobile communications, and in particular relates to a DC signal extraction structure and a filter equipped with the DC signal extraction structure. Background Art

[0002] As a key component in modern communication systems, the core function of filters is to effectively distinguish and transmit useful signals, while suppressing useless signals to ensure the efficiency and purity of signal transmission paths. With the rapid development of mobile communication technology, especially the rise of 5G communication technology, more stringent requirements are placed on filters. In order to improve the overall performance of communication equipment, the integrated integration of filters and antennas has become an inevitable trend, aiming to achieve miniaturization, high consistency and high stability of modules.

[0003] However, in the integration of filters and antennas, when a phase shifter needs to be connected, a key challenge is how to obtain a DC signal from the input or output port of the filter and output the DC signal to the phase shifter. In 5G communication systems, most filter ports use an inductive method, which not only meets the performance requirements of the filter, but also brings great difficulties to directly obtain DC signals. How to effectively extract DC signals while maintaining the miniaturization and high integration of the filter and antenna after integration has become a technical problem that needs to be solved urgently in the industry.

[0004] The industry's solution is to use the sleeve and the filter transmission port to form a capacitive coupling to transmit the signal in the main channel, while blocking the DC signal, and then further use a through-hole capacitor or a trap and a winding inductor to form an LC oscillation circuit and inductively connect the filter transmission port to perform frequency selection and extract the DC signal. However, this solution occupies a large filter volume and is difficult to achieve high integration, which limits the development of 5G communication technology. Summary of the invention

[0005] The primary purpose of the present invention is to solve at least one of the above problems and provide a DC signal extraction structure and filter.

[0006] In order to meet the various objectives of the present invention, the present invention adopts the following technical solutions:

[0007] A DC signal extraction structure is provided to meet one of the various purposes of the present invention. The DC signal extraction structure is used to be electrically connected to an input and / or output port of a radio frequency device. The port is an inductive transmission port. The inductive transmission port includes a transmission conductor. The DC signal extraction structure includes a printed board and an LC oscillation circuit, a main transmission circuit and a coupling structure arranged on the printed board.

[0008] The transmission conductor is coupled to the main transmission circuit through the coupling structure to convert the inductive transmission port into a capacitive transmission port; the LC oscillation circuit is connected to the transmission conductor to frequency-selectively extract the DC signal of the radio frequency device.

[0009] Furthermore, the printed board includes a first printed layer and a second printed layer which are stacked, the main transmission circuit and the coupling structure are arranged on the first printed layer, and the LC oscillation circuit is arranged on the second printed layer.

[0010] In one embodiment, the printed board includes a plurality of printed layers, and the plurality of printed layers form an integral structure.

[0011] In one embodiment, the coupling structure is a coupling ring, and the transmission conductor is inserted into the coupling ring.

[0012] In one embodiment, the printed circuit board also includes a third printed layer, the third printed layer constitutes one of the outer side surfaces of the printed circuit board, a first shielding ring is provided on the third printed layer, the transmission conductor is also passed through the first shielding ring, a second shielding ring is formed on one of the side plates of the shell, and the first shielding ring is in physical contact with the second shielding ring.

[0013] In one embodiment, the printed board is further provided with a plurality of shielding holes, which penetrate all printed layers of the printed board at the same time, wherein a plurality of shielding holes are arranged along the extension path of the shielding ring to form a first shielding area.

[0014] In one embodiment, another plurality of shielding holes among the plurality of shielding holes are arranged to form a second shielding area, the first shielding area is connected with the second shielding area to form a circuit arrangement area, and the circuits of each printed layer are arranged in the circuit arrangement area.

[0015] In one embodiment, the printed circuit board is provided with two signal output holes penetrating the printed circuit board, the LC oscillation circuit and the signal transmission hole are each connected to one signal output hole, pins are inserted in the two signal output holes, and the pins extend outside the shell.

[0016] In one embodiment, the printed board further includes a fourth printed layer, on which a phase shift circuit is provided, and the phase shift circuit is electrically connected to the LC oscillation circuit.

[0017] In one embodiment, the printed board is further provided with a fixing hole passing through all printed layers, and the RF device further includes a fixing piece, which passes through the side plate of the RF device and the fixing hole to fix the printed board and achieve grounding.

[0018] In one embodiment, the transmission conductor is a tap or a pin.

[0019] A filter is provided to meet one of the various purposes of the present invention, including a shell, a passage arranged in the shell, and a DC signal extraction structure as described in any one of the previous purposes, the passage including a plurality of resonant cavities, a resonator is arranged in the resonant cavity, a transmission conductor is formed on the port of the passage, and the transmission conductor is electrically connected to the DC signal extraction structure.

[0020] In one embodiment, the filter includes a plurality of paths, the plurality of paths correspond to a plurality of DC signal extraction structures, and the printed boards of the plurality of DC signal extraction structures are connected to form an integrated structure.

[0021] Compared with the prior art, the present invention has many advantages, including but not limited to:

[0022] First, the DC signal extraction structure of the present invention utilizes the capacitive coupling between the transmission conductor and the coupling structure to effectively block the DC signal output by the path. At the same time, through the LC oscillation circuit, the signal of the corresponding frequency band can be screened out from the blocked DC signal. Thus, not only the frequency selectivity is improved, but also the purity and stability of the output signal are ensured.

[0023] Secondly, the coupling structure and LC oscillation circuit of the DC signal extraction structure of the present invention are respectively arranged on the printed board, which greatly saves space. The stacked design of the printed board not only optimizes the internal structure of the radio frequency device, but also realizes the miniaturization and integration of the radio frequency device.

[0024] Furthermore, due to the adjustability of the LC oscillation circuit, the DC signal extraction structure can change its frequency response characteristics by adjusting the values ​​of inductance and capacitance according to different application requirements, thereby achieving accurate screening of signals in different frequency bands. This flexibility enables the DC signal extraction structure to be widely used in multiple fields such as communications, audio processing, and signal processing to meet the needs of different scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0026] Figure 1 FIG. 4 is a three-dimensional schematic diagram of a filter according to a typical embodiment of the present invention.

[0027] Figure 2 FIG. 4 is a partial cross-sectional schematic diagram of a filter according to a typical embodiment of the present invention.

[0028] Figure 3FIG. 1 is an exploded schematic diagram of a printed circuit board of a DC signal extraction structure according to a typical embodiment of the present invention.

[0029] Figure 4 FIG. 1 is a schematic top view of a first printed layer of a DC signal extraction structure according to a typical embodiment of the present invention.

[0030] Figure 5 FIG. 1 is a schematic top view of the second printed layer of the DC signal extraction structure according to a typical embodiment of the present invention.

[0031] Figure 6 FIG. 1 is a schematic top view of the third printed layer of the DC signal extraction structure according to a typical embodiment of the present invention.

[0032] Figure 7 The figure is a schematic diagram of the circuit principle of the DC signal extraction structure of the filter according to a typical embodiment of the present invention. DETAILED DESCRIPTION

[0033] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention and cannot be interpreted as limiting the present invention.

[0034] It will be understood by those skilled in the art that, unless expressly stated, the singular forms "one", "said", and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present invention refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. It should be understood that when we refer to an element as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or there may be an intermediate element. In addition, the "connection" or "coupling" used herein may include wireless connection or wireless coupling. The term "and / or" used herein includes all or any unit and all combinations of one or more associated listed items.

[0035] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as generally understood by those skilled in the art in the art to which the present invention belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless specifically defined as herein.

[0036] The present invention provides a DC signal extraction structure, which can convert an inductive transmission port of a radio frequency device into a capacitive transmission port and can also extract a DC signal from the radio frequency device.

[0037] To facilitate description of the technical solution of the DC signal extraction structure of the present invention, the present invention will take the RF device as a filter and the DC signal extraction structure arranged in the filter as an example to describe the present invention, but this should not be understood as a limitation to the present invention.

[0038] In an exemplary embodiment of the present invention, Figure 1 The filter 100 includes a housing 110, a passage, and a DC signal extraction structure, wherein the DC signal extraction structure is disposed in the housing 110. A plurality of resonant cavities are disposed in the passage, each of which has a resonator, and the plurality of resonators cooperate with each other to achieve filtering. In this embodiment, the present invention is described by taking two passages disposed in the housing 110 as an example, but this should not be construed as limiting the present invention.

[0039] Combination Figures 1 to 3 The signal port of the path is an input port or an output port to input or output a signal, and the signal port constitutes a transmission conductor 120. In this embodiment, it is recommended that the transmission conductor 120 is a tap or a pin, but this should not be construed as a limitation to the present invention.

[0040] The DC signal extraction structure includes a printed board 130, and the printed board 130 is stacked in sequence by a plurality of printed layers 131 along the same direction (this direction is referred to as the stacking direction). A circuit can be arranged on each printed layer 131, and the plurality of printed layers 131 constitute an integrated structure. It can be understood that the printed board 130 is an integrated structure as a whole, which is convenient for production and manufacturing.

[0041] Combination Figures 4 to 6 , the printed board 130 is provided with a conductor hole 132, and the conductor hole 132 penetrates all the printed layers 131 of the printed board 130 along the stacking direction. In this embodiment, the printed board 130 and the transmission conductor 120 are arranged on the same side of the filter 100, and the transmission conductor 120 penetrates the conductor hole 132 from one side of the printed layer 131 along the stacking direction, that is, the transmission conductor 120 penetrates all the printed layers 131 through the conductor hole 132.

[0042] Combination Figure 4The plurality of printed layers 131 include a first printed layer 141, on which a main transmission circuit 142 is arranged, and a coupling structure is formed on one end of the main transmission circuit 142, and the coupling structure includes a coupling ring 143, and the coupling ring 143 is sleeved with the conductor hole 132, that is, the conductor hole 132 is arranged in the coupling ring 143. When the transmission conductor 120 passes through the conductor hole 132, the coupling ring 143 is also passed through at the same time. Under the limitation of the conductor hole 132, the transmission conductor 120 and the coupling ring 143 are not in contact, so that capacitive coupling is achieved between the transmission conductor 120 and the coupling ring 143. In this embodiment, the signal port of the path is an inductive transmission port, because the transmission conductor 120 and the coupling ring 143 are capacitively coupled, so as to convert the inductive transmission port into a capacitive transmission port.

[0043] The path outputs a filtered signal to the outside through the transmission conductor 120, and the filtered signal includes a DC signal. However, due to the capacitive coupling between the transmission conductor 120 and the coupling ring 143, the DC signal is blocked on the transmission conductor 120 because the capacitor has the characteristic of blocking the DC current but allowing the AC current to pass through, and cannot be output to the main transmission circuit 142. In this embodiment, the capacitive coupling between the transmission conductor 120 and the coupling ring 143 is equivalent to the circuit schematic diagram of the DC signal extraction structure (see Figure 7 ) in capacitor C1.

[0044] In one embodiment, the bandwidth of the signal port is controlled by adjusting the diameter of the coupling ring 143 to control the size of the coupling ring 143. Generally speaking, the larger the diameter of the coupling ring 143, the stronger the capacitive coupling strength between the coupling ring 143 and the transmission conductor 120, and the wider the bandwidth of the signal port.

[0045] In another embodiment, the bandwidth of the signal port is controlled by adjusting the thickness of the coupling ring 143. Generally speaking, the thicker the coupling ring 143 is, the stronger the capacitive coupling between the coupling ring 143 and the transmission conductor 120 is, and the wider the bandwidth of the signal port is.

[0046] In an exemplary embodiment of the present invention, Figure 5The plurality of printed layers 131 further include a second printed layer 151, which is adjacent to and stacked with the first printed layer 141. An LC oscillator circuit 152 is arranged on the second printed layer 151, and the LC oscillator circuit 152 is used as a frequency selection circuit, so that the LC oscillator circuit 152 can filter out a DC signal of a corresponding frequency band from the DC signal blocked at the transmission conductor 120 (the DC signal of the corresponding frequency band is called a frequency selection signal), so as to complete the extraction of the frequency selection signal. In this embodiment, combined with Figure 5 and Figure 7 The LC oscillation circuit 152 includes the capacitor C2 and the inductor L1 , and the capacitor C2 and the inductor L1 form the LC oscillation circuit 152 .

[0047] Combination Figure 5 The printed board 130 is also provided with a signal output hole (the signal output hole is called the first signal output hole 133), the first signal output hole 133 penetrates all the printed layers 131 of the printed board 130, the LC oscillating circuit 152 is also connected to the first signal output hole 133, a pin is inserted in the first signal output hole 133 (the pin is called the first pin, not shown), and the first pin extends outside the housing 110. The LC oscillating circuit 152 is connected to the first pin, so that the LC oscillating circuit 152 outputs the frequency selection signal to the outside through the first pin, thereby realizing the signal output of the filter 100.

[0048] Combination Figure 4 , the printed board 130 is also provided with another signal output hole (the signal output hole is called the second signal output hole 134), the second signal output hole 134 penetrates all the printed layers 131 of the printed board 130, the main transmission circuit 142 is connected to the second signal output hole 134, a pin is inserted in the second signal output hole 134 (the pin is called the second pin, not shown), and the second pin extends to the outside of the housing 110. The main transmission circuit 142 is connected to the second pin, so that the main transmission circuit 142 outputs the signal in the path that is not blocked by the compatibility coupling between the coupling ring 143 and the transmission conductor 120, such as an AC signal, through the second pin, to achieve the adjustment of the filter 100 and the performance indicators of the filter 100.

[0049] Combination Figure 6The plurality of printed layers 131 of the printed board 130 further include a third printed layer 161, and the third printed layer 161 is arranged at the outermost side of the plurality of printed layers 131 along the stacking direction, that is, the third printed layer 161 constitutes one of the outer side surfaces of the printed board 130. A first shielding ring 162 is arranged on the third printed layer 161, and the first shielding ring 162 is sleeved with the coupling ring 143, that is, the coupling ring 143 is arranged in the first shielding ring 162.

[0050] Combination Figure 1 and Figure 2 The housing 110 is formed by a plurality of side panels 111, one of which is in contact with the third printed layer 161. For ease of description, the present invention is described below by taking one of the side panels 111 as the top panel 112 of the housing 110 as an example, but this should not be construed as limiting the present invention. A through hole 1121 is formed on the top panel 112, and a second shielding ring 113 is formed in the through hole 1121.

[0051] Combination Figure 1 and Figure 6 , the second shielding ring 113 corresponds to the first shielding ring 162, and the first shielding ring 162 is in physical contact with the second shielding ring 113. In this embodiment, it is recommended that the shape and size of the first shielding ring 162 correspond to the shape and size of the second shielding ring 113, so that the first shielding ring 162 and the second shielding ring 113 are in good contact and electrical connection is achieved.

[0052] The second shielding ring 113 cooperates with the first shielding ring 162 to physically divide the coupling signals between the various paths of the filter 100 and the signals output by each of the multiple channels, so that the isolation index between the various paths is better, so as to avoid electromagnetic leakage of the filter 100, ensure the electromagnetic leakage index of the filter 100, and thus optimize the communication performance of the filter 100.

[0053] In one embodiment, in combination Figures 4 to 6 The printed board 130 is also provided with a plurality of shielding holes 135, and the shielding holes 135 penetrate the printed board 130 along the stacking direction, that is, the shielding holes 135 simultaneously penetrate the multiple printed layers 131. In this embodiment, it is recommended that the shielding holes 135 are metallized vias to facilitate the transmission of current.

[0054] Combination Figure 6Multiple shielding holes 135 among the plurality of shielding holes 135 are extended along the extension path of the first shielding ring 162 to form a first shielding area 1361. The first shielding area 1361 strengthens the physical separation of the coupled signals between the various paths of the filter 100 and the signals output by each of the multiple channels, thereby improving the isolation index and optimizing the communication performance of the filter 100.

[0055] Another plurality of shielding holes 135 among the plurality of shielding holes 135 are arranged to form a second shielding area 1362, and the second shielding area 1362 is connected to the first shielding area 1361 to form a circuit layout area 136 in combination. Since the shielding holes 135 pass through the plurality of printed layers 131, a circuit layout area 136 is formed in each printed layer 131, and the circuits on each printed layer 131 are arranged in the circuit layout area 136 to shield signal interference through the circuit layout area 136, thereby optimizing the communication performance of the filter 100.

[0056] In this embodiment, combined with Figure 4 and Figure 5 The main transmission circuit 142 of the first printed layer 141 is arranged in the circuit arrangement area 136, and the LC oscillation circuit 152 of the second printed layer 151 is also arranged in the circuit arrangement area 136. The circuit arrangement area 136 encloses and physically separates the output signals of each path and the coupled signals between the paths, prevents crosstalk between the signals of each path, optimizes the isolation index, and thus improves the communication performance of the filter 100.

[0057] In one embodiment, the multiple printed layers 131 of the printed board 130 also include a fourth printed layer (not shown), and a phase shift circuit is provided on the fourth printed layer. The phase shift circuit is electrically connected to the LC oscillation circuit 152, and the LC oscillation circuit 152 outputs the acquired frequency-selected signal to the phase shift circuit for phase shifting through the phase shift circuit. It can be understood that by introducing the phase shift circuit, a phase shifter is integrated in the filter 100 to improve the integration of communication equipment, facilitate the miniaturization of communication equipment, and expand application scenarios.

[0058] In one embodiment, in combination Figure 4 and Figure 6, the printed circuit board 130 is also provided with a fixing hole (the fixing hole is referred to as the first fixing hole 137), and the first fixing hole 137 passes through the printed circuit board 130. The side plate 111 of the housing 110 is also provided with a fixing hole (the fixing hole is referred to as the second fixing hole, not shown), and the first fixing hole 137 corresponds to the second fixing hole. A fixing member (not shown) passes through the first fixing hole 137 and the second fixing hole at the same time to fix the printed circuit board 130 in the housing 110, so as to prevent the printed circuit board 130 from shaking in the housing 110, thereby improving the structural stability of the filter 100 and maintaining the electrical stability of the filter 100 when working. In this embodiment, it is recommended that the first fixing hole 137 and the second fixing hole are both screw holes, and the fixing member is a bolt or a screw, but this should not be understood as a limitation to the present invention.

[0059] In this embodiment, the shell 110 is made of metal material, and the fixing piece is also made of metal material. The fixing piece is connected to the printed circuit board 130 via the first fixing hole 137, so that the printed circuit board 130 can be electrically connected to the shell 110 via the fixing piece to achieve grounding.

[0060] In one embodiment, the circuits on each printed layer 131 are printed on the corresponding printed layer 131 by etching.

[0061] In one embodiment, the filter 100 includes a plurality of paths, and a plurality of DC signal extraction structures are provided corresponding to the plurality of paths, that is, each path corresponds to a DC signal extraction structure. In this embodiment, in order to facilitate the miniaturization of the filter 100, the printed boards 130 of the plurality of DC signal extraction structures are connected to form an integrated structure, so as to facilitate the miniaturization of the filter 100. For example, in combination with Figures 1 to 6 In this embodiment, the filter 100 includes two paths, and the two paths correspond to two DC signal extraction structures. The printed circuit boards 130 of the two DC signal extraction structures are connected to form an integrated structure, so that the filter 100 can be miniaturized.

[0062] In one embodiment, the filter 100 is also electrically connected to a phase shifter, and the LC oscillation circuit 152 of the filter 100 is connected to the phase shifter via a pin or a lead, so as to perform phase shifting on the frequency-selective signal output by the filter 100 .

[0063] In one embodiment, the radio frequency device may also be a combiner or a power divider.

[0064] In summary, the filter of the present invention realizes capacitive coupling through the transmission conductor and the coupling ring to block the DC signal, and screens out the DC signal of the corresponding frequency band from the DC signal through the LC oscillation circuit to achieve the corresponding electrical performance, and the coupling ring and the LC oscillation circuit are arranged on different printed layers of the printed circuit board to facilitate the miniaturization and integration of the filter.

[0065] The above description is only a preferred embodiment of the present invention and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present invention is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above inventive concept. For example, the above features are replaced with the technical features with similar functions invented in the present invention (but not limited to) to form a technical solution.

[0066] Although the subject matter has been described in language specific to structural features and / or methodological logical actions, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or actions described above. On the contrary, the specific features and actions described above are merely example forms of implementing the claims.

Claims

1. A DC signal extraction structure, characterized in that: The DC signal extraction structure is used to be electrically connected to the input and / or output port of the radio frequency device, the port is an inductive transmission port, the inductive transmission port includes a transmission conductor, and the DC signal extraction structure includes a printed board and an LC oscillation circuit, a main transmission circuit and a coupling structure arranged on the printed board; The transmission conductor is coupled to the main transmission circuit through the coupling structure to convert the inductive transmission port into a capacitive transmission port; The LC oscillation circuit is connected to the transmission conductor to frequency-selectively extract the DC signal of the radio frequency device.

2. The DC signal extraction structure according to claim 1, characterized in that: The printed board includes a first printed layer and a second printed layer which are stacked, the main transmission circuit and the coupling structure are arranged on the first printed layer, and the LC oscillation circuit is arranged on the second printed layer.

3. The DC signal extraction structure according to claim 2, characterized in that: The printed board includes a plurality of printed layers, and the plurality of printed layers form an integral structure.

4. The DC signal extraction structure according to claim 1, characterized in that: The coupling structure is a coupling ring, and the transmission conductor is inserted in the coupling ring.

5. The DC signal extraction structure according to claim 2, characterized in that: The printed circuit board also includes a third printed layer, which constitutes one of the outer side surfaces of the printed circuit board. A first shielding ring is provided on the third printed layer, and the transmission conductor is also passed through the first shielding ring. A second shielding ring is formed on one of the side panels of the shell of the radio frequency device, and the first shielding ring is in physical contact with the second shielding ring.

6. The DC signal extraction structure according to claim 5, characterized in that: The printed board is also provided with a plurality of shielding holes, which penetrate all the printed layers of the printed board at the same time, wherein a plurality of shielding holes are arranged along the extension path of the shielding ring to form a first shielding area.

7. The DC signal extraction structure according to claim 6, characterized in that: Another plurality of shielding holes among the plurality of shielding holes are arranged to form a second shielding area. The first shielding area is connected with the second shielding area to form a circuit arrangement area. The circuits of each printed layer are arranged in the circuit arrangement area.

8. The DC signal extraction structure according to claim 1, characterized in that: The printed board is provided with two signal output holes penetrating the printed board, the LC oscillation circuit and the signal transmission hole are respectively connected to one signal output hole, and pins are inserted in the two signal output holes.

9. The DC signal extraction structure according to claim 2, characterized in that: The printed board also includes a fourth printed layer, on which a phase shift circuit is provided, and the phase shift circuit is electrically connected to the LC oscillation circuit.

10. The DC signal extraction structure according to claim 2, characterized in that: The printed board is also provided with fixing holes passing through all printed layers, and the radio frequency device also includes fixing parts, which pass through the side plate of the radio frequency device and the fixing holes to fix the printed board and achieve grounding.

11. The DC signal extraction structure according to claim 1, characterized in that: The transmission conductor is a tap or a pin.

12. A filter, characterized in that: It includes a shell, a passage arranged in the shell, and a DC signal extraction structure as described in any one of claims 1 to 11, wherein the passage includes a plurality of resonant cavities, a resonator is arranged in the resonant cavity, a transmission conductor is formed on a port of the passage, and the transmission conductor is electrically connected to the DC signal extraction structure.

13. The filter according to claim 12, characterized in that The filter comprises a plurality of paths, the plurality of paths correspond to a plurality of DC signal extraction structures, and the printed boards of the plurality of DC signal extraction structures are connected to form an integrated structure.

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