A stacked high pass filter

Abstract

The present application relates to the technical fields of microwave circuit, and discloses a stacked high-pass filter, which comprises a first filter circuit, a first via, a second filter circuit, a second via and an interconnection layer, the first filter circuit and the second filter circuit are connected through the interconnection layer, the first via penetrates the first filter circuit and is connected with the interconnection layer, the second via penetrates the second filter circuit and is connected with 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.The stacked high-pass filter has the characteristics of miniaturization, high suppression and ultra-wideband, and realizes the high-pass filter circuit topology of double-layer wiring in the form of stacking the first filter substrate and the second filter substrate, and has the structural advantages of miniaturization and low cost of the microstrip filter and the performance advantages of high suppression and ultra-wideband of the suspended line filter.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of microwave circuit, and in particular to a stacked high-pass filter. BACKGROUND

[0002] In a radio frequency communication system, both the transmitter and the receiver need to filter out interference signals, and a microwave filter circuit is usually selected to separate useful radio frequency signals, and signals of a specific frequency are selected for processing. Microwave filter circuits are divided into low-pass filter circuits, high-pass filter circuits, band-pass filter circuits, and band-stop filter circuits. A high-pass filter circuit allows signals above the cutoff frequency to pass through, and exhibits high suppression performance for signals below the cutoff frequency.

[0003] In the design of a high-pass filter, in order to achieve high suppression and high rectangularity, a high-quality-factor suspended line is usually used for design, and a typical structure is as shown in Figure 2 The suspended line is arranged between air medium and low-K medium. The size of a typical suspended line high-pass filter is 45mm x 20mm x 10mm. The filter not only has a large volume, but also needs a fastening structure to meet electrical performance and mechanical assembly, and is difficult to adapt to the development trend of high-density integration.

[0004] Chinese patent CN112886936B discloses a novel miniature ultra-wideband high-pass filter, which comprises a cavity, a cover plate, a microwave substrate, a lumped capacitor and a lumped inductor. The microwave substrate is fixedly connected to the inner 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. The two open sides are provided with input / output ports. The application arranges high-frequency high-Q chip capacitors and inductor coils on the microwave substrate to realize circuit building of an LC high-pass filter. The disadvantages are 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 with the metal cavity by laser sealing, which is complicated. In addition, in addition to the assembly process requiring a lot of effort to screen capacitors, wind inductors and assemble and finish, such LC filters require a lot of manual debugging, time-consuming and laborious, and are difficult to meet the requirements of large quantities, rapidity and low cost. Moreover, the self-resonant frequency of the inductor coil and the chip capacitor is easy to drop into the passband frequency of the filter, causing the phenomenon of "pit" insertion loss in the passband.

[0005] Chinese invention patent application CN116259939A discloses a suspended strip line 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 strip line high-pass filter based on the alumina ceramic process is sequentially arranged from top to bottom as the upper conductor, the lower conductor and the metal ground layer, and the dielectric substrate is arranged between the upper conductor, the lower conductor, the lower conductor and the metal ground layer. The invention adopts two layers of alumina ceramic substrates to realize the suspended strip line structure. The disadvantage is that the dielectric constant of the ceramic substrate is relatively high, the lower electrode of the capacitor is connected in parallel with the metal ground and the ceramic substrate to form a parallel plate capacitor, which destroys the topology of the high-pass filter and forms resonance in the passband, and it is impossible to realize a larger cross-frequency passband. The 6GHz high-pass filter passband of the structure reaches 18GHz, and only a 3-frequency passband can be realized. In addition, the input and output ends of the invention are short-circuited to the ground structure, and in the case of leakage of the peripheral active circuit, a series capacitor is additionally required to be connected in series on the link to ensure the normal operation of the circuit.

[0006] Chinese invention patent CN115377633B discloses a high-pass filter with out-of-band rapid attenuation and ultra-wideband performance, which has a multi-layer metal pattern structure arranged in a hierarchical manner from top to bottom along the high-pass filter. The upper ground layer, the upper U-shaped coupling layer having a plurality of U-shaped coupling structures, the intermediate layer having a plurality of ground inductors and input / output structures located on the same level, the lower U-shaped coupling layer having a plurality of U-shaped coupling structures, and the lower ground layer are sequentially arranged in the high-pass filter. Two rows of metal through holes are further arranged on the high-pass filter. As can be seen, the invention is divided into an upper ground layer, an upper U-shaped coupling layer, an intermediate layer, a lower U-shaped coupling layer and a lower ground layer in structure. The disadvantage is that the passband is less than 2 times the frequency, the passband frequency is only 10GHz~18GHz, and the input and output ends are also short-circuited to the ground structure. SUMMARY

[0007] To solve the above problems, the present application provides a stacked high-pass filter, which can solve the problems of large volume, large debugging amount and narrow cross-frequency in the prior art.

[0008] The technical scheme adopted by the present application is as follows:

[0009] A stacked high-pass filter includes a first filter circuit, a first via, a second filter circuit, a second via and an interconnection layer. The first filter circuit and the second filter circuit are connected through the interconnection layer. The first via penetrates the first filter circuit and is connected with the interconnection layer, and the second via penetrates the second filter circuit and is connected with 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.

[0010] Further, the first filter circuit comprises a first filter substrate, an upper layer pattern and a lower layer pattern, the upper layer pattern is arranged on the upper surface of the first filter substrate, and the lower layer pattern is arranged on the lower surface of the first filter substrate.

[0011] Further, the upper layer pattern and the lower layer pattern each comprise input-output feed lines, conductive lines, capacitor electrodes, connecting lines and first ground lines, the input-output feed lines are connected with the capacitor electrodes and are open-circuited to the ground, each pair of capacitor electrodes is connected through the connecting lines, the connecting lines are connected with the first ground lines through the conductive lines, the impedance of the conductive lines is higher than a preset impedance value, and the first ground lines are arranged on both sides of the wide side of the first filter substrate.

[0012] Further, the second filter circuit comprises a second filter substrate, second ground lines and a metal ground, the second ground lines are 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.

[0013] Further, 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.

[0014] Further, the first through holes and the second through holes are located on the same vertical line.

[0015] Further, the first through holes penetrate the first filter substrate and are connected with the first ground lines, and the second through holes penetrate the second filter substrate and are connected with the second ground lines and the metal ground.

[0016] Further, the interconnection layer is connected with the second ground lines, and the first ground lines, the second ground lines and the interconnection layer have a ground attribute.

[0017] Further, the stacked high-pass filter is a generalized Chebyshev function response filter, the conductive lines are equivalent to parallel inductors in a filter topology structure and are connected with the first ground lines to realize grounding, the first filter substrate and a pair of capacitor electrodes constitute a parallel-plate capacitor and are equivalent to series capacitors in the filter topology structure, and the connecting lines are used to connect the parallel inductors and the series capacitors in the filter topology structure.

[0018] Further, the interconnection layer is prearranged on the lower surface of the first ground lines through an electroplating process.

[0019] The present application has the following beneficial effects:

[0020] (1) The stacked high-pass filter of the present invention has the characteristics of miniaturization, high suppression and ultra-wideband. It realizes the high-pass filter circuit topology with double wiring in the form of stacking the first filter substrate and the second filter substrate, which combines the structural advantages of miniaturization and low cost of microstrip filter and the performance advantages of high suppression and ultra-wideband of suspension line filter.

[0021] (2) In this invention, the first filter substrate and the second filter substrate are stacked and assembled through an interconnection layer, resulting in good filter consistency and advantages such as automated assembly, no debugging required, high batch production efficiency, and low cost. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a stacked high-pass filter structure according to the present invention.

[0023] Figure 2 This is a schematic diagram of a traditional suspension wire structure.

[0024] Figure 3 This is a schematic diagram (top view) of the first filter substrate and its upper layer graphic structure.

[0025] Figure 4 This is a schematic diagram (bottom view) of the first filter substrate and its underlying graphic structure.

[0026] Figure 5 This is a perspective view of the first filter substrate and its upper and lower surface layer patterns.

[0027] Figure 6 This is a schematic diagram of the second filter substrate and its upper layer pattern structure.

[0028] Figure 7 This is a schematic diagram of the second filter substrate and its underlying pattern structure.

[0029] Figure 8 This is a schematic diagram of a stacked high-pass filter structure.

[0030] Figure 9 for Figure 8 The circuit diagram shown is of a stacked high-pass filter.

[0031] Figure 10 Local structure for stacked high-pass filters ( Figure 5 (See diagram at point A in the middle)

[0032] Figure 11 for Figure 10 The diagram shows a partial circuit schematic of a stacked high-pass filter.

[0033] Figure 12 This is a schematic diagram of the lower layer pattern and interconnect layer of the first filter substrate.

[0034] Reference numerals: 20-First filter circuit, 201-First filter substrate, 202-Upper layer pattern, 203-Lower layer pattern, 2001-Input / output feed line, 2002-Wire, 2003-Capacitor electrode, 2004-Connection line, 2005-First ground line, 30-First via, 40-Second filter circuit, 401-Second filter substrate, 402-Second ground line, 403-Metal ground, 50-Second via, 60-Interconnect layer. Detailed Implementation

[0035] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments are now described. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention; that is, the described embodiments are only a part of the embodiments of the invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0036] Example 1

[0037] like Figure 1 As shown, this embodiment provides a stacked high-pass filter, including a first filter circuit 20, a first via 30, a second filter circuit 40, a second via 50, and an interconnect layer 60. The first filter circuit 20 and the second filter circuit 40 are connected through the interconnect layer 60; the first via 30 passes through the first filter circuit 20 and is connected to the interconnect layer 60, and the second via 50 passes through the second filter circuit 40 and is connected to the interconnect layer 60; the dielectric constant of the first filter circuit 20 is greater than a first preset value, and the dielectric constant of the second filter circuit 40 is less than a second preset value, wherein the first preset value is greater than the second preset value.

[0038] Preferably, such as 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. 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, both the upper pattern 202 and the lower pattern 203 include an input / output feed line 2001, a wire 2002, a capacitor electrode 2003, a connecting line 2004, and a first ground line 2005. The input / output feed line 2001 is connected to the capacitor electrode 2003 and is open to ground. Each pair of capacitor electrodes 2003 is connected by a connecting line 2004. The connecting line 2004 is connected to the first ground line 2005 through the wire 2002. The impedance of the wire 2002 is higher than a preset impedance value. The first ground line 2005 is disposed on both sides of the wide edge of the first filter substrate 201.

[0039] Preferably, such as Figure 6、 Figure 7 As shown in FIG. 2, the second filter circuit 40 comprises a second filter substrate 401, a second ground line 402 and a metal ground 403. The second ground line 402 is arranged on the wide sides 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.

[0040] Preferably, the first through hole 30 is arranged on the wide sides of the first filter substrate 201, as shown in FIG. 3. Figure 3 、 Figure 4 Preferably, the second through hole 50 is arranged on the wide sides of the second filter substrate 401, as shown in FIG. 4. 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. 5. Figure 5

[0041] Preferably, the first through hole 30 penetrates the first filter substrate 201 and is connected with the first ground line 2005; the second through hole 50 penetrates the second filter substrate 401 and is connected with the second ground line 402 and the metal ground 403; the interconnection layer 60 is connected with the second ground line 402, and the first ground line 2005, the second ground line 402 and the interconnection layer 60 are of ground property.

[0042] Preferably, the filter structure of the stacked high-pass filter in the embodiment is shown in FIG. 6. Figure 5 、 Figure 10 and Figure 11 Due to the mutual coupling between the inductors, the generalized Chebyshev function response can be achieved. The wire 2002 can be equivalent to a parallel inductor in the filter topology structure, and is connected with the first ground line 2005 to achieve grounding; the first filter substrate 201 and the pair of capacitor electrodes 2003 constitute a parallel-plate capacitor, which is equivalent to a series capacitor in the filter topology structure; the connecting line 2004 is used to connect the parallel inductor and the series capacitor in the filter topology structure. By adjusting the size of the connecting line 2004, the impedance matching of the stacked high-pass filter in a wide frequency band can be achieved, and the standing wave in the passband can be less than 2.

[0043] Preferably, the first filter circuit 20 in the embodiment can adopt a ceramic circuit, and the first through hole 30 can adopt a TCV (Through Ceramic Via) hole; the second filter circuit 40 can adopt a glass circuit, and the second through hole 50 can adopt a TGV (Through Glass Via) hole.

[0044] ​More preferably, the substrate of the ceramic circuit must have a high dielectric constant (preferably, in the range of 11.5 to 67) and a thin thickness (preferably, in the range of less than or equal to 0.127 mm) to form a high-capacitance parallel-plate capacitor. Conversely, the substrate of the glass circuit must have a low dielectric constant (preferably, in the range of 2 to 5.2) and a large thickness (preferably, in the range of 0.4 mm to 1 mm) to avoid the capacitor electrode 2003 forming a parallel-plate capacitor with the metal ground 403, which would disrupt the high-pass filtering topology of the filter and affect the ultra-wideband high-pass filtering characteristics.

[0045] Preferably, such as Figure 12 As shown, the interconnect layer 60 is pre-placed on the lower surface of the first ground wire 2005 by an electroplating process, and the first filter circuit 20, the second filter circuit 40, and the interconnect layer 60 are stacked using a thermosetting bonding process. The interconnect layer 60 can be a gold-tin solder with an area slightly smaller than the second ground wire 402 and a thickness of 6~8μm, wherein the gold-tin weight percentage of the gold-tin solder is preferably Au80Sn20.

[0046] In summary, this invention achieves a high-pass filter circuit topology with double-layer wiring by stacking a first filter substrate and a second filter substrate. It combines 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. The first and second filter substrates are assembled via an interconnect layer, resulting in good filter consistency and advantages such as automated assembly, no debugging required, high mass production efficiency, and low cost.

[0047] Example 2

[0048] This embodiment is based on embodiment 1:

[0049] This embodiment provides a stacked high-pass filter, employing, as shown in... Figure 8 and Figure 9 The structure shown demonstrates a 2.5GHz high-pass filter designed using a ceramic substrate and a glass substrate. The filter measures 8mm × 5mm × 0.9mm, achieves an 8x passband, and has a passband frequency of up to 20GHz. It offers 45dBc suppression at 2.2GHz compared to 2.5GHz, and features advantages such as miniaturization, low cost, high out-of-band rejection, ultra-wideband capability, mass production, and no tuning required.

[0050] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

[0051] In the description of the application, it should be noted that the indicated orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship commonly used when the application is used, only for the convenience of describing the application and simplifying the description, and does not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application. In addition, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

Claims

1. A stacked high-pass filter, characterized by, The application relates to a filter circuit, which comprises a first filter circuit (20), a first via hole (30), a second filter circuit (40), a second via hole (50) and an interconnection layer (60), wherein the first filter circuit (20) and the second filter circuit (40) are connected through the interconnection layer (60); the first via hole (30) penetrates the first filter circuit (20) and is connected with the interconnection layer (60), and the second via hole (50) penetrates the second filter circuit (40) and is connected with 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. 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). The upper layer pattern (202) and the lower layer pattern (203) both comprise an input-output feed line (2001), a conductive wire (2002), a capacitor electrode (2003), a connecting line (2004) and a first grounding line (2005), wherein the input-output feed line (2001) is connected with the capacitor electrode (2003) and is open-circuited to the ground, each pair of capacitor electrodes (2003) are connected through the connecting line (2004), the connecting line (2004) is connected with the first grounding line (2005) through the conductive wire (2002), the impedance of the conductive wire (2002) is higher than a preset impedance value, and the first grounding line (2005) is arranged on the two sides of the wide side of the first filter substrate (201).

2. The stacked high-pass filter of claim 1, 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 the two 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).

3. The stacked high-pass filter of claim 2, wherein, The first via hole (30) is arranged on the two sides of the wide side of the first filter substrate (201), and the second via hole (50) is arranged on the two sides of the wide side of the second filter substrate (401).

4. The stacked high-pass filter of claim 2, wherein, The first via hole (30) and the second via hole (50) are located on the same vertical line.

5. The stacked high-pass filter of claim 2, wherein, The first via hole (30) penetrates the first filter substrate (201) and is connected with the first grounding line (2005), and the second via hole (50) penetrates the second filter substrate (401) and is connected with the second grounding line (402) and the metal ground (403).

6. A stacked high-pass filter according to claim 5, wherein, The interconnection layer (60) is connected with the second grounding line (402), and the first grounding line (2005), the second grounding line (402) and the interconnection layer (60) have a ground attribute.

7. The stacked high-pass filter of claim 2, wherein, The stacked high-pass filter is a generalized Chebyshev function response filter; the wire (2002) is equivalent to a parallel inductance in a filter topology structure, and is connected with a first ground wire (2005) to realize grounding; the first filter substrate (201) and a pair of capacitor electrodes (2003) constitute a parallel-plate capacitor, which is equivalent to a series capacitor in the filter topology structure; and the connecting wire (2004) is used for connecting the parallel inductance and the series capacitor in the filter topology structure.

8. The stacked high-pass filter of claim 2, wherein, The interconnection layer (60) is pre-plated on the lower surface of the first ground wire (2005) through an electroplating process.

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