Stacked high-pass filter

Abstract

The invention relates to the technical field of microwave circuits, and discloses a stacked high-pass filter, which comprises a first filter circuit, a first through hole, a second filter circuit, a second through hole and an interconnection layer, and is characterized in that the first filter circuit and the second filter circuit are connected through the interconnection layer; the first through hole penetrates through the first filter circuit and is connected with the interconnection layer, and the second through hole penetrates through the second filter circuit and is connected with the interconnection layer; the dielectric constant of the first filter circuit is larger than a first preset value, the dielectric constant of the second filter circuit is smaller than a second preset value, and the first preset value is larger than the second preset value. The stacked high-pass filter provided by the invention has the characteristics of miniaturization, high suppression, ultra wide band and the like, realizes double-layer wiring high-pass filter circuit topology in a form of stacking the first filter substrate and the second filter substrate, and has the structural advantages of miniaturization and low cost of a microstrip filter and the performance advantages of high suppression and ultra wide band of a suspended line filter.

Description

Technical Field

[0001] The present invention relates to the technical field of microwave circuits, and in particular to a stacked high-pass filter. Background Art

[0002] In radio frequency communication systems, both transmitters and receivers need to filter out interfering signals. Microwave filter circuits are typically used to isolate useful radio frequency signals and select signals of specific frequencies for processing. Microwave filter circuits are categorized into low-pass, high-pass, band-pass, and band-stop filters. High-pass filters allow signals above the cutoff frequency to pass through, while providing high rejection for signals below the cutoff frequency.

[0003] In the design of high-pass filters, in order to achieve high suppression and high rectangularity, a high-quality factor suspension line is usually used for design. Its typical structure is as follows Figure 2 As shown, the suspension line is placed between the air dielectric and the low-K dielectric. A typical suspension line high-pass filter measures 45mm × 20mm × 10mm. This filter is not only bulky but also requires a rigid structure to meet electrical performance and mechanical assembly requirements, making it difficult to adapt to the trend of high-density integration.

[0004] Chinese invention patent CN112886936B discloses a new type of miniature ultra-wideband high-pass filter, including a cavity, a cover plate, a microwave substrate, a lumped capacitor and a lumped inductor, wherein the microwave substrate is fixedly connected to the bottom surface of the cavity, the lumped capacitor and the lumped inductor are fixedly arranged on the microwave substrate, and the cover plate is encapsulated above the cavity, forming a semi-open structure as a whole, with input / output ports provided on both open sides. This invention places high-frequency, high-Q chip capacitors and inductor coils on the microwave substrate to realize the circuit construction of the LC high-pass filter. The disadvantage is that the microwave substrate, chip capacitors and inductor coils need to be assembled in a metal cavity, and the cover plate needs to be fixed to the metal cavity by laser sealing, and the assembly process is cumbersome. In addition, in addition to the assembly process requiring a lot of energy to screen capacitors, wind inductors, and assemble and finish, this type of LC filter requires a lot of manual debugging, which is time-consuming and labor-intensive, and is difficult to meet the requirements of large-scale, fast, and low-cost output. Moreover, the self-resonant frequency of the inductor coil and chip capacitor easily falls within the passband frequency of the filter, causing the insertion loss to "fall" within the passband.

[0005] Chinese invention patent application CN116259939A discloses a suspended stripline high-pass filter based on an alumina ceramic process, comprising an upper conductor, a lower conductor, a metal ground layer, and a dielectric substrate. The suspended stripline high-pass filter based on the alumina ceramic process comprises, from top to bottom, an upper conductor, a lower conductor, and a metal ground layer, with dielectric substrates disposed between the upper conductor, the lower conductor, and the lower conductor, respectively. This invention utilizes two layers of alumina ceramic substrates to achieve a suspended stripline structure. However, the ceramic substrates have a high dielectric constant, and the lower electrode of the capacitor, the metal ground layer, and the ceramic substrate together form a parallel plate capacitor. When connected in parallel in the circuit, this disrupts the topology of the high-pass filter, creates resonance within the passband, and prevents the implementation of a wider cross-octave passband. This 6GHz high-pass filter has a passband of up to 18GHz, achieving only a 3-octave passband. Furthermore, the input and output terminals of this invention are short-circuited to ground. In the event of leakage in the peripheral active circuit, additional series capacitors are required to isolate the DC current in the link to ensure proper circuit operation.

[0006] Chinese invention patent CN115377633B discloses a high-pass filter with fast out-of-band attenuation and ultra-wideband performance. Its multi-layered metal pattern structure is arranged in a hierarchical manner along the high-pass filter from top to bottom, comprising: an upper ground layer; an upper U-shaped coupling layer with multiple U-shaped coupling structures; an intermediate layer with multiple ground inductors and input / output structures located on the same layer, the input / output structures partially extending to the outer wall of the high-pass filter; a lower U-shaped coupling layer with multiple U-shaped coupling structures; and a lower ground layer. The high-pass filter is also provided with two rows of metal vias. This invention structurally comprises an upper ground layer, an upper U-shaped coupling layer, an intermediate layer, a lower U-shaped coupling layer, and a lower ground layer. However, its disadvantages are that its passband is less than 2 times the frequency, with a passband frequency of only 10 GHz to 18 GHz, and the input and output terminals are also short-circuited to ground. Summary of the Invention

[0007] In order to solve the above problems, the present invention proposes a stacked high-pass filter, which can solve the problems of large size, large debugging requirements, and insufficient cross-frequency width in the prior art.

[0008] The technical solution adopted in the present invention is as follows: A stacked high-pass filter includes a first filter circuit, a first through hole, a second filter circuit, a second through hole, and an interconnection layer, wherein the first filter circuit and the second filter circuit are connected via the interconnection layer; the first through hole passes through the first filter circuit and is connected to the interconnection layer, and the second through hole passes through the second filter circuit and is connected to the interconnection layer; the dielectric constant of the first filter circuit is greater than a first preset value, the dielectric constant of the second filter circuit is less than a second preset value, and the first preset value is greater than the second preset value.

[0009] Furthermore, the first filter circuit includes a first filter substrate, an upper pattern and a lower pattern, wherein the upper pattern is arranged on the upper surface of the first filter substrate, and the lower pattern is arranged on the lower surface of the first filter substrate.

[0010] Furthermore, the upper and lower graphics both include input and output feed lines, wires, capacitor electrodes, connecting wires and a first ground wire. The input and output feed lines are connected to the capacitor electrodes and are open to the ground. Each pair of capacitor electrodes is connected by a connecting wire, and the connecting wire is connected to the first ground wire through a wire. The impedance of the wire is higher than a preset impedance value. The first ground wire is arranged on both sides of the wide side of the first filter substrate.

[0011] Furthermore, the second filter circuit includes a second filter substrate, a second grounding line and a metal ground, the second grounding line is arranged on both sides of the wide side of the upper surface of the second filter substrate, and the metal ground is arranged on the lower surface of the second filter substrate.

[0012] Furthermore, the first through holes are arranged on both sides of the wide side of the first filter substrate, and the second through holes are arranged on both sides of the wide side of the second filter substrate.

[0013] Furthermore, the first through hole and the second through hole are located on the same vertical line.

[0014] Furthermore, the first through hole passes through the first filter substrate and is connected to the first ground line; the second through hole passes through the second filter substrate and is connected to the second ground line and the metal ground.

[0015] Furthermore, the interconnection layer is connected to the second ground line, and the first ground line, the second ground line and the interconnection layer are of ground properties.

[0016] Furthermore, the stacked high-pass filter is a generalized Chebyshev function response filter; the wire is equivalent to a parallel inductor in the filter topology structure, and is connected to the first grounding wire to achieve grounding; the first filter substrate and a pair of capacitor electrodes constitute a parallel plate capacitor, which is equivalent to a series capacitor in the filter topology structure; the connecting wire is used to connect the parallel inductor and the series capacitor in the filter topology structure.

[0017] Furthermore, the interconnection layer is pre-deposited on the lower surface of the first grounding line through an electroplating process.

[0018] The beneficial effects of the present invention are: (1) The stacked high-pass filter of the present invention has the characteristics of miniaturization, high suppression, and ultra-wideband. It realizes a double-layer wiring high-pass filter circuit topology in the form of a stack of a first filter substrate and a second filter substrate, combining the structural advantages of miniaturization and low cost of microstrip filters with the performance advantages of high suppression and ultra-wideband of suspended line filters. (2) In the present invention, the first filter substrate and the second filter substrate are stacked and assembled through an interconnection layer, and the filter has good consistency and has the advantages of automated assembly, no debugging, high batch production efficiency and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The figure is a schematic diagram of the structure of a stacked high-pass filter of the present invention.

[0020] Figure 2 Schematic diagram of the traditional suspension line structure.

[0021] Figure 3 Schematic diagram of the first filter substrate and its upper graphic structure (top view).

[0022] Figure 4 Schematic diagram of the first filter substrate and its underlying graphic structure (bottom view).

[0023] Figure 5 This is a schematic diagram (perspective view) of the first filter substrate and the upper and lower surface graphic structures.

[0024] Figure 6 This is a schematic diagram of the second filter substrate and its upper graphic structure.

[0025] Figure 7 This is a schematic diagram of the second filter substrate and its underlying graphic structure.

[0026] Figure 8 Schematic diagram of the stacked high-pass filter structure.

[0027] Figure 9 for Figure 8 The circuit schematic of the stacked high-pass filter is shown.

[0028] Figure 10 The local structure of the stacked high-pass filter ( Figure 5 Schematic diagram of point A in the middle.

[0029] Figure 11 for Figure 10 The schematic diagram of the partial structure of the stacked high-pass filter is shown.

[0030] Figure 12 This is a schematic diagram of the lower layer pattern and interconnection layer of the first filter substrate.

[0031] Figure numerals: 20-first filtering circuit, 201-first filtering substrate, 202-upper layer pattern, 203-lower layer pattern, 2001-input and output feed lines, 2002-conducting wire, 2003-capacitor electrode, 2004-connecting line, 2005-first ground line, 30-first through hole, 40-second filtering circuit, 401-second filtering substrate, 402-second ground line, 403-metal ground, 50-second through hole, 60-interconnection layer. DETAILED DESCRIPTION

[0032] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific embodiments of the present invention are now described. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. That is, the embodiments described are only part of the embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0033] Example 1 like Figure 1 As shown, this embodiment provides a stacked high-pass filter, including a first filter circuit 20, a first through-hole 30, a second filter circuit 40, a second through-hole 50, and an interconnection layer 60. The first filter circuit 20 and the second filter circuit 40 are connected via the interconnection layer 60; the first through-hole 30 passes through the first filter circuit 20 and is connected to the interconnection layer 60, and the second through-hole 50 passes through the second filter circuit 40 and is connected to the interconnection layer 60; the dielectric constant of the first filter circuit 20 is greater than a first preset value, the dielectric constant of the second filter circuit 40 is less than a second preset value, and the first preset value is greater than the second preset value.

[0034] Preferably, if Figures 3 to 5 As shown, the first filter circuit 20 includes a first filter substrate 201, an upper pattern 202, and a lower pattern 203, wherein the upper pattern 202 is disposed on the upper surface of the first filter substrate 201, and the lower pattern 203 is disposed on the lower surface of the first filter substrate 201. More preferably, the upper pattern 202 and the lower pattern 203 each include an input / output feeder 2001, a wire 2002, a capacitor electrode 2003, a connecting wire 2004, and a first grounding wire 2005, wherein the input / output feeder 2001 is connected to the capacitor electrode 2003 and is open to ground, each pair of capacitor electrodes 2003 is connected via a connecting wire 2004, and the connecting wire 2004 is connected to the first grounding wire 2005 via the wire 2002, the impedance of the wire 2002 being higher than a preset impedance value, and the first grounding wire 2005 is disposed on both sides of the broadside of the first filter substrate 201.

[0035] Preferably, if Figure 6 、 Figure 7As shown, the second filter circuit 40 includes a second filter substrate 401 , a second ground line 402 and a metal ground 403 , wherein the second ground line 402 is arranged on both sides of the wide side of the upper surface of the second filter substrate 401 , and the metal ground 403 is arranged on the lower surface of the second filter substrate 401 .

[0036] Preferably, the first through holes 30 are provided on both sides of the wide side of the first filter substrate 201, such as Figure 3 、 Figure 4 As shown; the second through hole 50 is provided on both sides of the wide side of the second filter substrate 401, as shown Figure 6 、 Figure 7 The first through hole 30 and the second through hole 50 are located on the same vertical line, as shown in FIG. Figure 5 shown.

[0037] Preferably, the first through hole 30 passes through the first filter substrate 201 and is connected to the first ground line 2005; the second through hole 50 passes through the second filter substrate 401 and is connected to the second ground line 402 and the metal ground 403; the interconnection layer 60 is connected to the second ground line 402, and the first ground line 2005, the second ground line 402 and the interconnection layer 60 are ground properties.

[0038] Preferably, the filter in the stacked high-pass filter of this embodiment is constructed as follows: Figure 5 、 Figure 10 and Figure 11 As shown, due to the mutual coupling between the inductors, a generalized Chebyshev function response can be achieved. Conductor 2002 is equivalent to a parallel inductor in the filter topology and is connected to first ground wire 2005 for grounding. The first filter substrate 201 and a pair of capacitor electrodes 2003 form a parallel plate capacitor, equivalent to a series capacitor in the filter topology. Connecting wire 2004 is used to connect the parallel inductor and the series capacitor in the filter topology. Adjusting the size of connecting wire 2004 can achieve impedance matching for the stacked high-pass filter over a wide bandwidth, with standing wave coefficients within the passband being less than 2.

[0039] Preferably, the first filter circuit 20 of this embodiment may adopt a ceramic circuit, and the first through hole 30 may adopt a TCV (Through Ceramic Via, i.e., ceramic through hole technology); the second filter circuit 40 may adopt a glass circuit, and the second through hole 50 may adopt a TGV (Through Glass Via, i.e., glass through hole technology).

[0040] More preferably, the ceramic circuit substrate should have a high dielectric constant (preferably in the range of 11.5-67) and a thin thickness (preferably in the range of 0.127 mm or less) to form a high-capacitance parallel-plate capacitor. Conversely, the glass circuit substrate should have a low dielectric constant (preferably in the range of 2-5.2) and a thick thickness (preferably in the range of 0.4 mm-1 mm) to prevent the capacitor electrode 2003 and the metal ground 403 from forming a parallel-plate capacitor, which would disrupt the high-pass filter topology and affect the ultra-wideband high-pass filter characteristics.

[0041] Preferably, if Figure 12 As shown, interconnect layer 60 is pre-deposited on the lower surface of first ground line 2005 via electroplating, and first filter circuit 20, second filter circuit 40, and interconnect layer 60 are stacked using a thermocompression bonding process. Interconnect layer 60 can be made of a gold-tin solder material with a thickness of 6-8 μm and a surface area slightly smaller than second ground line 402. The weight percentage of gold-tin in the gold-tin solder material is preferably Au80Sn20.

[0042] In summary, the present invention achieves a dual-layer high-pass filter circuit topology by stacking a first filter substrate and a second filter substrate. This combines the structural advantages of microstrip filters, which are miniaturized and low-cost, with the high rejection and ultra-wideband performance of suspended line filters. The interconnection layer between the first and second filter substrates enables assembly of the substrates, resulting in high filter consistency and the advantages of automated assembly, no debugging required, high batch production efficiency, and low cost.

[0043] Example 2 This embodiment is based on embodiment 1: This embodiment provides a stacked high-pass filter, using Figure 8 and Figure 9 The structure shown in the figure uses ceramic and glass substrates to design a 2.5GHz high-pass filter. This filter measures 8mm × 5mm × 0.9mm, achieves an 8x passband, and reaches a passband frequency of 20GHz. The 2.2GHz frequency point has a 45dBc rejection relative to the 2.5GHz frequency point. It offers the advantages of miniaturization, low cost, high out-of-band rejection, ultra-wideband, mass production, and no debugging required.

[0044] The foregoing description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein and should not be construed as excluding other embodiments. Rather, the present invention can be used in various other combinations, modifications, and environments and can be modified within the scope of the concept described herein through the above teachings or techniques or knowledge in the relevant field. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention are intended to be protected by the appended claims.

[0045] In the description of the present invention, it should be noted that the orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, or are conventionally positioned or arranged when the present invention is in use. These are intended solely to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," etc., are used solely for distinction and should not be construed as indicating or implying relative importance.

Claims

1. A stacked high-pass filter, characterized in that: The invention comprises a first filter circuit (20), a first through hole (30), a second filter circuit (40), a second through hole (50), and an interconnection layer (60); the first filter circuit (20) and the second filter circuit (40) are connected via the interconnection layer (60); the first through hole (30) passes through the first filter circuit (20) and is connected to the interconnection layer (60); the second through hole (50) passes through the second filter circuit (40) and is connected to the interconnection layer (60); the dielectric constant of the first filter circuit (20) is greater than a first preset value, the dielectric constant of the second filter circuit (40) is less than a second preset value, and the first preset value is greater than the second preset value.

2. A stacked high-pass filter according to claim 1, characterized in that: The first filter circuit (20) comprises a first filter substrate (201), an upper layer pattern (202), and a lower layer pattern (203), wherein the upper layer pattern (202) is arranged on the upper surface of the first filter substrate (201), and the lower layer pattern (203) is arranged on the lower surface of the first filter substrate (201).

3. A stacked high-pass filter according to claim 2, characterized in that: The upper-layer graphics (202) and the lower-layer graphics (203) both comprise input and output feed lines (2001), wires (2002), capacitor electrodes (2003), connecting lines (2004), and first grounding lines (2005); the input and output feed lines (2001) are connected to the capacitor electrodes (2003) and are open to the ground; each pair of capacitor electrodes (2003) is connected via a connecting line (2004); the connecting line (2004) is connected to the first grounding line (2005) via a wire (2002); the impedance of the wire (2002) is higher than a preset impedance value; and the first grounding line (2005) is arranged on both sides of the wide side of the first filter substrate (201).

4. The stacked high-pass filter according to claim 3, wherein: The second filter circuit (40) comprises a second filter substrate (401), a second grounding line (402) and a metal ground (403), wherein the second grounding line (402) is arranged on both sides of the wide side of the upper surface of the second filter substrate (401), and the metal ground (403) is arranged on the lower surface of the second filter substrate (401).

5. The stacked high-pass filter according to claim 4, wherein: The first through holes (30) are arranged on both sides of the wide side of the first filter substrate (201), and the second through holes (50) are arranged on both sides of the wide side of the second filter substrate (401).

6. The stacked high-pass filter according to claim 4, wherein: The first through hole (30) and the second through hole (50) are located on the same vertical line.

7. The stacked high-pass filter according to claim 4, wherein: The first through hole (30) passes through the first filter substrate (201) and is connected to the first grounding line (2005); the second through hole (50) passes through the second filter substrate (401) and is connected to the second grounding line (402) and the metal ground (403).

8. The stacked high-pass filter according to claim 7, wherein: The interconnection layer (60) is connected to the second grounding line (402), and the first grounding line (2005), the second grounding line (402) and the interconnection layer (60) are of ground properties.

9. The stacked high-pass filter according to claim 4, wherein: The stacked high-pass filter is a generalized Chebyshev function response filter; the conductor (2002) is equivalent to a parallel inductor in a filter topology structure, and is connected to a first grounding wire (2005) to achieve grounding; the first filter substrate (201) and a pair of capacitor electrodes (2003) form a parallel plate capacitor, which is equivalent to a series capacitor in the filter topology structure; the connecting wire (2004) is used to connect the parallel inductor and the series capacitor in the filter topology structure.

10. The stacked high-pass filter according to claim 4, wherein: The interconnection layer (60) is pre-deposited on the lower surface of the first ground line (2005) through an electroplating process.

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