A fully automatic reconfigurable compact dual-band filtering device

Abstract

The application discloses a kind of full-automatic reconfigurable compact dual-passband filter device, belong to microwave communication technical field, including input coupling and matching circuit, low-frequency dual-mode resonant circuit, high-frequency dual-mode resonant circuit, intermediate coupling circuit, output coupling and matching circuit and DC bias circuit, it is difficult to realize independent electric control adjustment of two passband center frequencies of existing dual-passband filter device, and the technical problem that structure is not compact enough, band interval isolation is lower, the independent adjustment of dual-passband can be realized in the application, reduces artificial intervention, can quickly complete the reconfiguration of frequency band, to improve the flexibility and convenience of system, adopt multi-mode resonator structure, successfully realize compact design, significantly reduce the volume, suitable for limited application scenarios of space, can effectively suppress the interference of other frequency bands, further improve the stability and efficiency of communication system, improve the reliability and stability of system, ensure its long-term reliable operation.

Description

Technical Field

[0001] This invention belongs to the field of microwave communication technology, and specifically relates to a fully automatic, reconfigurable, compact dual-passband filter. Background Technology

[0002] With the rapid development of modern communication technology, the scarcity of spectrum resources and the increasing demand for efficient and flexible frequency-selective filtering devices in communication systems are becoming increasingly prominent. As a core component of the overall communication system, filtering devices are widely used in signal transmission, frequency selection, and interference suppression. However, traditional filtering device designs are mostly fixed, lacking flexibility and reconfigurability, making them difficult to adapt to rapidly changing spectrum demands, especially under the requirements of dynamic spectrum management and bandwidth reconfigurability.

[0003] Especially in multi-band communication systems and miniaturized devices, traditional filtering devices often fail to meet the comprehensive requirements of size, performance, and flexibility. Traditional dual-passband filters typically employ mechanical adjustment methods or fixed designs, which not only reduce the flexibility of the filtering device but also increase the complexity of manual intervention and adjustment. As communication equipment develops towards higher integration and lower power consumption, higher demands are placed on the compact design and high efficiency of filtering devices.

[0004] Therefore, how to develop a compact and efficient filter device with automatic reconfiguration capability has become a key issue in the current research and design of filter devices.

[0005] In existing technologies, dual-passband filters typically employ a fixed-frequency design, which cannot flexibly adapt to changes in frequency band requirements. To achieve adjustable dual-passband filters, some technologies have introduced mechanical adjustment or voltage control methods. Mechanical adjustment usually relies on manual methods such as knobs, levers, or adjusting screws for frequency band adjustment, which not only increases operational complexity but also results in slow adjustment speeds, making it difficult to meet the needs of real-time spectrum reconfiguration.

[0006] Another type of technology uses voltage control regulation, adjusting the frequency response of the filter by changing the values ​​of components such as capacitors and inductors. While this method is more flexible than mechanical adjustment, it places higher demands on the structure of the filter, requiring a larger solder pad area, making it difficult to maintain the compactness and miniaturization advantages of the final filter. Furthermore, the performance of the filter gradually deteriorates during passband adjustment, affecting the overall stability of the device.

[0007] Although some designs employ compact structures and multimode resonator technology to reduce the size and weight of the filter, these designs often compromise performance in pursuit of miniaturization, especially in high-frequency applications, and still face challenges of insufficient performance and adjustability.

[0008] In summary, existing reconfigurable filtering devices still suffer from problems such as slow adjustment speed, poor accuracy, and poor adaptability, and cannot effectively meet the growing demands of modern communication systems. Summary of the Invention

[0009] The purpose of this invention is to provide a fully automatic, reconfigurable, compact dual-passband filter device, which aims to improve the flexibility and performance of the system through fully automatic electronic control adjustment, and to overcome the shortcomings of the prior art.

[0010] To achieve the above objectives, the present invention adopts the following technical solution: A fully automatic reconfigurable compact dual-passband filter includes an input coupling and matching circuit, a low-frequency dual-mode resonant circuit, a high-frequency dual-mode resonant circuit, an intermediate coupling circuit, an output coupling and matching circuit, and a DC bias circuit. The output of the input coupling and matching circuit is divided into two paths. One path is connected to the input coupling section of the low-frequency dual-mode resonant circuit through interpolation coupling. The other path is connected to the intermediate coupling circuit through the fourth DC blocking capacitor. The intermediate coupling circuit includes a second microstrip feed line and a third microstrip feed line, with the second microstrip feed line connected to the third microstrip feed line via interpolation coupling. The second microstrip feed line is connected to the input coupling section of the low-frequency dual-mode resonant circuit and the input coupling section of the high-frequency dual-mode resonant circuit respectively by interpolation coupling. The third microstrip feed line is connected to the output coupling section of the high-frequency dual-mode resonant circuit via interpolation coupling. The third microstrip feed line is also connected to the output coupling and matching circuit via the fifth DC blocking capacitor. The output coupling and matching circuit is connected to the output coupling section of the low-frequency dual-mode resonant circuit via interpolation coupling. The multiple DC power-on terminals are respectively connected to the varactor diodes contained in the input coupling and matching circuit, the low-frequency dual-mode resonant circuit, the high-frequency dual-mode resonant circuit, the intermediate coupling circuit, and the output coupling and matching circuit, and are used to independently provide tuning voltage.

[0011] Preferably, the input coupling and matching circuit, the low-frequency dual-mode resonant circuit, the high-frequency dual-mode resonant circuit, the intermediate coupling circuit, and the output coupling and matching circuit together constitute a symmetrical coupling structure. The interdigitated coupling method includes interdigitated microstrip line structure and auxiliary branch interdigitated microstrip line structure.

[0012] Preferably, the input coupling and matching circuit, the low-frequency dual-mode resonant circuit, the high-frequency dual-mode resonant circuit, the intermediate coupling circuit, the output coupling and matching circuit, and the DC bias circuit are all disposed on the metal layer of the dielectric substrate and are all implemented using a microstrip line structure.

[0013] Preferably, the low-frequency dual-mode resonant circuit includes an input coupling section and an output coupling section. The input coupling section of the low-frequency dual-mode resonant circuit includes a first microstrip line structure, and the output coupling section of the low-frequency dual-mode resonant circuit includes a second microstrip line structure. The high-frequency dual-mode resonant circuit includes an input coupling section and an output coupling section. The input coupling section of the high-frequency dual-mode resonant circuit has a third microstrip line structure, and the output coupling section of the high-frequency dual-mode resonant circuit has a fourth microstrip line structure.

[0014] Preferably, the input coupling and matching circuit includes a 50Ω microstrip feed line, a third DC blocking capacitor, a first microstrip feed line, a first varactor diode pad structure, a first varactor diode, and a third DC power supply terminal; the 50Ω microstrip feed line is connected to the first microstrip feed line through the third DC blocking capacitor; the upper left part of the first microstrip feed line is connected to the first varactor diode pad structure through a high-resistivity microstrip line; the first varactor diode is connected between the first varactor diode pad structure and the upper left ground terminal; the lower part of the first microstrip feed line is connected to the third DC power supply terminal through a high-resistivity microstrip line.

[0015] Preferably, the low-frequency dual-mode resonant circuit includes a first microstrip line structure, an output coupling section, a second microstrip line structure, a first microstrip block structure, a first DC blocking capacitor, a second DC blocking capacitor, a first DC power-on terminal, a second DC power-on terminal, a second varactor diode, a third varactor diode, an upper left ground terminal, and an upper right ground terminal. The left end of the first microstrip line structure is connected to the first DC power-on terminal via the first DC blocking capacitor, and the upper part of the first DC power-on terminal is connected to the upper left ground terminal via the second varactor diode. The right side of the first microstrip line structure is connected to the second microstrip line structure via the first microstrip block structure, and the upper right part of the first microstrip line structure is directly connected to the upper left ground terminal. The right end of the second microstrip line structure is connected to the second DC power-on terminal via the second DC blocking capacitor, and the upper part of the second DC power-on terminal is connected to the upper right ground terminal via the third varactor diode.

[0016] Preferably, the high-frequency dual-mode resonant circuit includes a third microstrip line structure, a fourth microstrip line structure, a second microstrip block structure, a seventh DC blocking capacitor, an eighth DC blocking capacitor, a fifth DC power-on terminal, a sixth DC power-on terminal, a sixth varactor diode, a seventh varactor diode, a lower left ground terminal, and a lower right ground terminal. The left end of the third microstrip line structure is connected to the fifth DC power supply terminal via the seventh DC blocking capacitor, and the lower part of the fifth DC power supply terminal is connected to the lower left ground terminal via the sixth varactor diode; the right side of the third microstrip line structure is connected to the fourth microstrip line structure via the second microstrip block structure, and the lower right part of the third microstrip line structure is directly connected to the lower left ground terminal; the right end of the fourth microstrip line structure is connected to the sixth DC power supply terminal via the eighth DC blocking capacitor, and the lower part of the sixth DC power supply terminal is connected to the lower right ground terminal via the seventh varactor diode.

[0017] Preferably, the intermediate coupling circuit includes a second microstrip feed line, a third microstrip feed line, a fourth DC blocking capacitor, a fifth DC blocking capacitor, a fourth DC power-on terminal, a seventh DC power-on terminal, a fifth varactor diode, an eighth varactor diode, a lower left ground terminal, and a lower right ground terminal; the second microstrip feed line and the third microstrip feed line are coupled to each other through an interdigitated microstrip line structure; the lower part of the second microstrip feed line is connected to the fourth DC power-on terminal via a high-impedance microstrip line, and the lower part of the fourth DC power-on terminal is connected to the lower left ground terminal via the fifth varactor diode; the lower part of the third microstrip feed line is connected to the seventh DC power-on terminal via a high-impedance microstrip line, and the lower part of the seventh DC power-on terminal is connected to the lower right ground terminal via the eighth varactor diode.

[0018] Preferably, the output coupling and matching circuit includes a fourth microstrip feed line, a sixth DC blocking capacitor, an output 50Ω microstrip feed line, a second varactor diode pad structure, a fourth varactor diode, an eighth DC power-on terminal, and a ground terminal at the upper right. The right side of the fourth microstrip feed line is connected to the output 50Ω microstrip feed line via the sixth DC blocking capacitor; the upper right part of the fourth microstrip feed line is connected to the second varactor diode pad structure via a microstrip high-resistance line, and the second varactor diode pad structure is connected to the upper right ground terminal via the fourth varactor diode; the lower part of the fourth microstrip feed line is connected to the eighth DC power supply terminal via a high-resistance microstrip line.

[0019] Preferably, the DC bias circuit includes multiple independent DC power-on terminals, specifically connected as follows: The first DC power-on terminal and the second DC power-on terminal are respectively connected to the second varactor diode and the third varactor diode in the low-frequency dual-mode resonant circuit, and are used to independently adjust the center frequency of the low-frequency passband. The fifth and sixth DC power-on terminals are connected to the sixth and seventh varactor diodes in the high-frequency dual-mode resonant circuit, respectively, to independently adjust the center frequency of the high-frequency passband. The third and eighth DC power-on terminals are respectively connected to the first varactor diode in the input coupling and matching circuit and the fourth varactor diode in the output coupling and matching circuit, and are used to control the in-band response of the dual passband and compensate for processing errors. The fourth DC power-on terminal and the seventh DC power-on terminal are respectively connected to the fifth varactor diode and the eighth varactor diode in the intermediate coupling circuit to adjust the frequency position of the transmission zero point. All of the DC power terminals are independently powered.

[0020] This invention discloses a fully automatic reconfigurable compact dual-passband filter, designed to improve system flexibility and performance through fully automatic electronic control adjustment, addressing shortcomings in existing technologies. The dual-passband filter of this invention features fully automatic reconfigurability, enabling precise control of the adjustment circuit performance via external power supply and independent adjustment of both passbands. Furthermore, compared to traditional mechanically adjustable reconfigurable filters, it reduces manual intervention, allowing for rapid frequency band reconfiguration, thus enhancing system flexibility and convenience. Employing a multimode resonator structure, it achieves a compact design, significantly reducing size and weight, making it suitable for space-constrained applications such as small communication devices, mobile terminals, and portable devices. The filter can generate transmission zeros outside multiple frequency bands, providing excellent passband performance, selectivity, and out-of-band rejection, effectively suppressing interference from other frequency bands and further improving the stability and efficiency of the communication system. By adjusting the varactor diode between the feeder and the resonator, the passband stability of the filter is ensured under different environmental conditions, preventing frequency drift or interference fluctuations from causing system failure, thereby improving system reliability and stability and ensuring long-term reliable operation. Attached Figure Description

[0021] Figure 1 A schematic diagram of a fully automatic, reconfigurable, compact dual-passband filter device according to an embodiment of the present invention; Figure 2 A schematic diagram of a dual-mode resonator structure in a fully automatic, reconfigurable, compact dual-passband filter according to an embodiment of the present invention; Figure 3 A schematic diagram of the equivalent microstrip circuit of a dual-mode resonator structure in a fully automatic reconfigurable compact dual-passband filter device according to an embodiment of the present invention; Figure 4 A schematic diagram of the equivalent microstrip odd-mode circuit of a dual-mode resonator structure in a fully automatic reconfigurable compact dual-passband filter according to an embodiment of the present invention; Figure 5 A schematic diagram of the equivalent microstrip even-mode circuit of a dual-mode resonator structure in a fully automatic reconfigurable compact dual-passband filter device according to an embodiment of the present invention; Figure 6 A schematic diagram showing the specific dimensions of a fully automatic, reconfigurable, compact dual-passband filter device according to an embodiment of the present invention; Figure 7A fully automatic, reconfigurable, compact dual-passband filter in this embodiment of the invention features a low-frequency passband S. 11 Schematic diagram of adjustable response; Figure 8 A fully automatic, reconfigurable, compact dual-passband filter in this embodiment of the invention features a low-frequency passband S. 21 Schematic diagram of adjustable response; Figure 9 shows a fully automatic, reconfigurable, compact dual-passband filter in an embodiment of the present invention. The high-frequency passband S... 11 Schematic diagram of adjustable response; Figure 10 A fully automatic, reconfigurable, compact dual-passband filter with high-frequency passband S in an embodiment of the present invention 21 Schematic diagram of adjustable response; In the diagram: 1. Input 50Ω microstrip feed line; 2. First varactor diode pad structure; 3. First varactor diode; 4. Second varactor diode; 5. First DC blocking capacitor; 6. Fourth DC blocking capacitor; 7. Second microstrip feed line; 8. First microstrip line structure; 9. Upper left ground terminal; 10. First microstrip block structure; 11. Upper right ground terminal; 12. Second microstrip line structure; 13. Third microstrip feed line; 14. Fifth DC blocking capacitor; 15. Second DC blocking capacitor; 16. Third varactor diode; 17. Second DC blocking capacitor; 18. Fourth varactor diode; 19. Second varactor diode pad structure; 20. Output 50Ω microstrip feed line; 21. 22. Dielectric substrate, 23. Sixth DC blocking capacitor, 24. Eighth DC power supply terminal, 25. Fourth microstrip feed line, 26. Seventh DC power supply terminal, 27. Eighth varactor diode, 28. Seventh varactor diode, 29. Eighth DC blocking capacitor, 30. Sixth DC power supply terminal, 31. Lower right ground terminal, 32. Fourth microstrip line structure, 33. Second microstrip block structure, 34. Third microstrip line structure, 35. Lower left ground terminal, 36. Fifth DC power supply terminal, 37. Seventh DC blocking capacitor, 38. Sixth varactor diode, 39. Fifth varactor diode, 40. Fourth DC power supply terminal, 41. First microstrip feed line, 42. Third DC power supply terminal, 43. Third DC blocking capacitor. Detailed Implementation

[0022] Depend on Figures 1-10 The fully automatic reconfigurable compact dual-passband filter shown includes an input coupling and matching circuit, a low-frequency dual-mode resonant circuit, a high-frequency dual-mode resonant circuit, an intermediate coupling circuit, an output coupling and matching circuit, and a DC bias circuit. The output of the input coupling and matching circuit is divided into two paths. One path is connected to the input coupling section of the low-frequency dual-mode resonant circuit through interpolation coupling. The other path is connected to the intermediate coupling circuit through the fourth DC blocking capacitor 7. The intermediate coupling circuit includes a second microstrip feed line 8 and a third microstrip feed line 14. The second microstrip feed line 8 is connected to the third microstrip feed line 14 by interpolation coupling. The second microstrip feed line 8 is connected to the input coupling section of the low-frequency dual-mode resonant circuit and the input coupling section of the high-frequency dual-mode resonant circuit respectively by interpolation coupling. The third microstrip feed line 14 is connected to the output coupling section of the high-frequency dual-mode resonant circuit via interpolation coupling. The third microstrip feed line 14 is also connected to the output coupling and matching circuit through the fifth DC blocking capacitor 15. The output coupling and matching circuit is connected to the output coupling section of the low-frequency dual-mode resonant circuit via interpolation coupling. The multiple DC power-on terminals are respectively connected to the varactor diodes contained in the input coupling and matching circuit, the low-frequency dual-mode resonant circuit, the high-frequency dual-mode resonant circuit, the intermediate coupling circuit, and the output coupling and matching circuit, and are used to independently provide tuning voltage.

[0023] The input coupling and matching circuit, the low-frequency dual-mode resonant circuit, the high-frequency dual-mode resonant circuit, the intermediate coupling circuit, and the output coupling and matching circuit together constitute a symmetrical coupling structure. The interdigitated coupling method includes interdigitated microstrip line structure and auxiliary branch interdigitated microstrip line structure.

[0024] The input coupling and matching circuit, the low-frequency dual-mode resonant circuit, the high-frequency dual-mode resonant circuit, the intermediate coupling circuit, the output coupling and matching circuit, and the DC bias circuit are all disposed on the metal layer of the dielectric substrate 22 and are all implemented using a microstrip line structure.

[0025] The DC bias circuit includes multiple independent DC power-on terminals, with the specific connections as follows: The first DC power-on terminal 6 and the second DC power-on terminal 16 are respectively connected to the second varactor diode 5 and the third varactor diode 17 in the low-frequency dual-mode resonant circuit, and are used to independently adjust the center frequency of the low-frequency passband. The fifth DC power-on terminal 36 and the sixth DC power-on terminal 30 are respectively connected to the sixth varactor diode 38 and the seventh varactor diode 28 in the high-frequency dual-mode resonant circuit, and are used to independently adjust the center frequency of the high-frequency passband. The third DC power-on terminal 42 and the eighth DC power-on terminal 24 are respectively connected to the first varactor diode 3 in the input coupling and matching circuit and the fourth varactor diode 19 in the output coupling and matching circuit, and are used to control the in-band response of the dual passband and compensate for processing errors. The fourth DC power-on terminal 40 and the seventh DC power-on terminal 26 are respectively connected to the fifth varactor diode 39 and the eighth varactor diode 27 in the intermediate coupling circuit to adjust the frequency position of the transmission zero point. All of the DC power terminals are independently powered.

[0026] A dielectric substrate 22 and a metal layer located on the dielectric substrate, wherein a filter device circuit is constructed on the metal layer. The filter device circuit includes: a first varactor diode pad structure 2, a second varactor diode pad structure 20, a first DC power-on terminal 6, a second DC power-on terminal 16, a third DC power-on terminal 42, a fourth DC power-on terminal 40, a fifth DC power-on terminal 36, a sixth DC power-on terminal 30, a seventh DC power-on terminal 26, an eighth DC power-on terminal 24, a first varactor diode 3, a second varactor diode 5, a third varactor diode 17, a fourth varactor diode 19, a fifth varactor diode 39, a sixth varactor diode 38, a seventh varactor diode 28, an eighth varactor diode 27, a first microstrip line structure 9, a second microstrip line structure 10, a second microstrip line structure 11, a second microstrip line structure 12, a third microstrip line structure 13, a fourth varactor diode 19, a fifth varactor diode 39, a sixth varactor diode 38, a seventh varactor diode 28, an eighth varactor diode 27, a first microstrip line structure 9, a second microstrip line structure 13, a second microstrip line structure 14, a third microstrip line structure 15, a fourth microstrip line structure 16, a fifth microstrip line structure 17, a sixth microstrip line structure 18, a seventh microstrip line structure 19, a seventh microstrip line structure 10, a fifth microstrip line structure 11, a sixth microstrip line structure 12, a seventh microstrip line structure 13, a seventh microstrip line structure 14, a fifth microstrip line structure 15, a sixth microstrip line structure 16, a seventh microstrip line structure 17, a seventh microstrip line structure 1 Microstrip line structure 13, third microstrip line structure 34, fourth microstrip line structure 32, first microstrip block structure 11, second microstrip block structure 33, first DC blocking capacitor 4, second DC blocking capacitor 18, third DC blocking capacitor 43, fourth DC blocking capacitor 7, fifth DC blocking capacitor 15, sixth DC blocking capacitor 23, seventh DC blocking capacitor 37, eighth DC blocking capacitor 29, upper left ground terminal 10, upper right ground terminal 12, lower left ground terminal 35, lower right ground terminal 31, first microstrip feed line 41, second microstrip feed line 8, third microstrip feed line 14, fourth microstrip feed line 25, input and output 50Ω microstrip feed line 121, where: The right side of the input 50Ω microstrip feed line 1 is connected to the third DC blocking capacitor 43. The right side of the third DC blocking capacitor 43 is connected to the first microstrip feed line 41. The upper left part of the first microstrip feed line 41 is connected to the first varactor diode pad structure 2 through a section of high-resistivity microstrip line. The first varactor diode pad structure 2 is connected to the first varactor diode 3. The upper part of the first varactor diode 3 is connected to the connected upper left ground terminal 10. The upper right part of the first microstrip feed line 41 is coupled to the first microstrip line structure 9 through interdigitated microstrip lines and auxiliary stub interdigitated microstrip lines. The left end of the first microstrip line structure 9 is a low-resistivity microstrip line used as a pad connected to the first DC blocking capacitor 4. The first DC blocking capacitor is connected to the first DC power-on terminal 6. The upper part of the first DC power-on terminal 6 is connected to the second varactor diode... The diode 5 is connected, the second varactor diode 5 is connected to the upper left ground terminal 10, the right side of the first microstrip line structure 9 is connected to the second microstrip line structure 13 through the first microstrip block structure 11, and the upper part of the right side of the first microstrip line structure 9 is connected to the upper left ground terminal 10; the lower part of the first microstrip feed line 41 is connected to the third DC power supply terminal 42 through the high-resistivity microstrip line structure, the right side of the first microstrip feed line 41 is connected to the second microstrip feed line 8 through the fourth DC blocking capacitor 7, the upper left side of the second microstrip feed line 8 is coupled to the first microstrip line structure 9 through the auxiliary stub interdigitated microstrip line, the lower part of the second microstrip feed line 8 is connected to the fourth DC power supply terminal 40 through the high-resistivity microstrip line structure, the lower part of the fourth DC power supply terminal 40 is connected to the fifth varactor diode 39, and the fifth varactor diode 39 is connected to the fifth varactor diode 39. The lower part of the second microstrip feed line 8 is connected to the lower left ground terminal 35. The lower part of the second microstrip feed line 8 is coupled to the third microstrip line structure 34 through the interdigitated microstrip line structure and the auxiliary stub interdigitated microstrip line. The left end of the third microstrip line structure 34 is a low-resistance microstrip line as a pad connected to the seventh DC blocking capacitor 37. The seventh DC blocking capacitor 37 is connected to the fifth DC power supply terminal 36. The lower part of the fifth DC power supply terminal 36 is connected to the sixth varactor diode 38. The sixth varactor diode 38 is connected to the lower left ground terminal 35. The right side of the third microstrip line structure 34 is connected to the fourth microstrip line structure 32 through the second microstrip block structure 33. The lower right side of the third microstrip line structure 34 is connected to the lower left ground terminal 35. The right side of the second microstrip feed line 8 is connected to the third microstrip feed line 14 through the interdigitated microstrip line. The structures are interconnected. The upper part of the third microstrip feed line 14 is coupled to the second microstrip line structure 13 via an auxiliary stub interdigitated microstrip line. The lower part of the third microstrip feed line 14 is connected to the seventh DC power-on terminal 26 via a high-resistivity microstrip line structure. The lower part of the seventh DC power-on terminal 26 is connected to the eighth varactor diode 27. The lower part of the eighth varactor diode 27 is connected to the lower right ground terminal 31. The lower part of the third microstrip feed line 14 is also coupled to the fourth microstrip line structure 32 via an interdigitated microstrip line structure and an auxiliary stub interdigitated microstrip line. The right end of the fourth microstrip line structure 32 is a low-resistivity microstrip line serving as a pad connected to the eighth DC blocking capacitor 29. The eighth DC blocking capacitor 29 is connected to the sixth DC power-on terminal 30. The lower part of the sixth DC power-on terminal 30 is connected to the seventh varactor diode 28.The seventh varactor diode 28 is connected to the lower right ground terminal 31. The right side of the third microstrip feed line 14 is connected to the fourth microstrip feed line 25 through the fifth DC blocking capacitor 15. The upper right part of the fourth microstrip feed line 25 is connected to the second varactor diode pad structure 20 through a section of microstrip high-resistivity line. The second varactor diode pad structure 20 is connected to the fourth varactor diode 19. The upper part of the fourth varactor diode 19 is connected to the upper right ground terminal 12. The upper left part of the fourth microstrip feed line 25 is connected to the second microstrip line through interdigitated microstrip lines and auxiliary stub interdigitated microstrip lines. Structures 13 are mutually coupled. The right end of the second microstrip line structure 13 is a low-impedance microstrip line serving as a pad connected to the second DC blocking capacitor 18. The second DC blocking capacitor 18 is connected to the second DC power-on terminal 16. The upper part of the second DC power-on terminal 16 is connected to the third varactor diode 17. The third varactor diode 17 is connected to the upper right ground terminal 12. The lower part of the fourth microstrip feed line 25 is connected to the eighth DC power-on terminal 24 through a high-impedance microstrip line structure. The right side of the fourth microstrip feed line 25 is connected to the output 50Ω microstrip feed line 21 through the sixth DC blocking capacitor 23.

[0027] The filtering device is characterized in that it comprises a low-frequency dual-mode resonator consisting of a first DC power-on terminal 6, a second DC power-on terminal 16, a second varactor diode 5, a third varactor diode 17, a first microstrip line structure 9, a second microstrip line structure 13, a first microstrip block structure 11, a first DC blocking capacitor 4, a second DC blocking capacitor 18, a left upper ground terminal 10, and a right upper ground terminal 12, for providing two transmission poles for the low-frequency passband of the filtering device; and a high-frequency dual-mode resonator consisting of a fifth DC power-on terminal 36, a sixth DC power-on terminal 30, a fifth varactor diode 39, a sixth varactor diode 38, a seventh varactor diode 28, a third microstrip line structure 34, a fourth microstrip line structure 32, a second microstrip block structure 33, an eighth DC blocking capacitor 29, a left lower ground terminal 35, and a right lower ground terminal 31, for providing two transmission poles for the high-frequency passband of the filtering device. The relative positions of the first microstrip block structure 11 and the second microstrip block structure 33 directly affect the transmission pole positions of each dual-mode resonator, thereby precisely controlling the passband width of the filter device.

[0028] The filtering device is characterized in that the first DC power-on terminal 6, the second DC power-on terminal 16, the fifth DC power-on terminal 36 and the sixth DC power-on terminal 30 in the filtering device are respectively composed of two low-resistance microstrip lines and one high-resistance microstrip line, wherein one low-resistance microstrip line serves as the DC power-on terminal and the other low-resistance microstrip line serves as the pad for the DC blocking capacitor and the varactor diode.

[0029] The filtering device is characterized in that the first varactor diode 3, the fourth varactor diode 19, the fifth varactor diode 39 and the eighth varactor diode 27 of the filtering device can control the in-band response of the dual passband. At the same time, these varactor diodes can be adjusted according to actual processing errors and engineering implementation, thereby making the filtering device easier to implement and apply in engineering.

[0030] The filtering device is characterized in that the interdigitated microstrip line structure and the auxiliary stub interdigitated microstrip line structure involved in the filtering device are not the only implementation of the present invention, and can also be implemented by other means such as lumped capacitors.

[0031] The specific models of the DC blocking capacitors and varactor diodes involved in this filtering device can be selected according to the actual manufacturer and the specific performance requirements of the filtering device; the models are not unique.

[0032] The filter device includes an input 50Ω microstrip feed line 1, an output 50Ω microstrip feed line 21, a third DC blocking capacitor 43, a fourth DC blocking capacitor 7, a fifth DC blocking capacitor 15, a sixth DC blocking capacitor 23, a first microstrip feed line 41, a second microstrip feed line 8, a third microstrip feed line 14, and a fourth microstrip feed line 25. These components together form the coupling path between the input and output terminals. Through this design, the filter device introduces two transmission zeros outside the two passbands, thereby not only improving the isolation between the two passbands but also enhancing out-of-band rejection and selectivity. Furthermore, adjusting the dimensions of the interdigitated microstrip line structure between the second microstrip feed line 8 and the third microstrip feed line 14 can effectively adjust the frequency position of the transmission zeros.

[0033] The filter device uses the second varactor diode 5 and the third varactor diode 17 to independently adjust the position of the low-frequency passband of the filter device; and uses the sixth varactor diode 38 and the seventh varactor diode 28 to independently adjust the position of the high-frequency passband of the filter device.

[0034] The overall structure of the filter device is symmetrical from left to right, and the values ​​and physical parameters of its varactor diodes, DC blocking capacitors, and other components are all symmetrical and consistent.

[0035] like Figure 2 A schematic diagram of a dual-mode resonator structure for a fully automated, reconfigurable, compact dual-passband filter device according to an embodiment of the present invention is shown. Since the dimensions of the intercalation microstrip lines, auxiliary stub intercalation microstrip line structures, and DC-powered pads are relatively small compared to the overall resonator structure, their influence on the resonator's resonant frequency is extremely small and almost negligible; therefore, they are omitted from the diagram. Furthermore, to further achieve a compact and miniaturized overall device, the microstrip lines are appropriately bent in the resonator's structural design. Figure 3The corresponding equivalent microstrip circuit diagram is given. By adding electric and magnetic walls to the overall structure, its corresponding odd-mode and even-mode equivalent circuits are obtained, as shown below. Figure 4 and Figure 5 As shown. The corresponding odd-mode and even-mode input admittances. Y ino and Y ine The following formula can be used for calculation.

[0036] At this point, simply let Y ino and Y ine This allows us to obtain the odd-mode resonant frequencies corresponding to the two-mode resonators. f o Even mode resonant frequency f e .

[0037] It is also worth noting that the simulation tool used in this invention is Sonnet EM, the dielectric substrate is MgO with a dielectric constant of 9.8, the metal thickness of the microstrip line is 0.035 mm, the dielectric substrate thickness is 0.5 mm, the varactor diode used is model MA46H120, which can operate between 0V and 10V, the variable capacitance range is 0.2 pF to 1.1 pF, and the DC blocking capacitor used is model ATC550L. Figure 6 A schematic diagram showing the specific dimensions of a fully automatic, reconfigurable, compact dual-passband filter device according to an embodiment of the present invention is provided. l 0 = 6.84 mm l 1 = 1.92 mm l 2 = 0.54 mm l 3 = 1mm l 4 = 3mm l 5 = 2.04 mm l 6 = 0.46 mm l 7 = 4.94 mm l 8 = 1mm l 9 = 1.92mm l 10 =0.5mm, l 11 =0.46mm, l 12=1.08mm, l 13 =0.48mm, l 14 =1.14mm, l 15 =10.76mm, l 16 =1.44mm, l 17 =0.92mm, l 18 =0.2mm, l 19 =0.18mm, l 20 =1.44mm, l 21 =0.88mm, l 22 =0.92mm, w 0=39.6mm, w 1=2.46mm, w 2=1mm, w 3=1mm, w 4=0.14mm, w 5=0.04mm, w 6=0.36mm, w 7=0.76mm, w 8=0.04mm, w 9=0.16mm, w 10 =0.36mm, w 11 =0.48mm, w 12 =0.52mm, w 13 =0.54mm, w 14 =0.14mm, w 15 =0.6mm, w 16 =0.64mm, w 17 =2.46mm, w 18 =2.18mm, w 19 =0.16mm, w 20 =25.28mm, s 0=0.08mm, s 1=0.08mm, s2 = 0.04 mm s 3 = 0.08 mm s 4 = 0.04 mm s 5 = 0.04 mm s 6 = 0.52 mm s 7 = 1.9mm. This implementation case is only one of the solutions.

[0038] Figure 7 and Figure 8 This invention demonstrates a fully automatic, reconfigurable, compact dual-passband filter with a low-frequency passband. S 11 and S 21 A schematic diagram illustrating the adjustable response. In this filter device, the varactor diode values ​​have a high degree of freedom; the shown value is one special case. Specifically, C m2 and C m3 It primarily controls the in-band performance of the dual passband, while C m1 and C m4 These primarily control the frequency positions of the low-frequency and high-frequency passbands, respectively. In this example, the fixed... C m2 =0.3pF, C m3 =1.1pF, C m4 =1.1pF, and will C m1 The filter was adjusted from 1.1 pF to 0.2 pF. As can be seen from the figure, the low-frequency passband center frequency of the filter changed from 345.5 MHz to 386.5 MHz, an adjustment range of 11.2%, while the high-frequency passband frequency remained unchanged.

[0039] Figure 9 and Figure 10 This invention demonstrates the high-frequency passband of the filtering device in an embodiment of the present invention. S 11 and S 21 A schematic diagram of the adjustable response. At this point, fixed... C m1 =1.1pF, C m3 =1.1pF, gradually... C m4 Adjusted from 1.1 pF to 0.2 pF, and at the same time C m2The first two settings were 0.3pF, and the latter two were adjusted to 0.5pF. It is easy to see from the graph that the high-frequency passband center frequency of the filter changed from 578MHz to 667MHz, an adjustment range of 14.3%, while the low-frequency passband frequency remained unchanged during this process.

[0040] Meanwhile, while independently adjusting the low-frequency and high-frequency passband positions, the out-of-band rejection consistently remains above 30dB, and the isolation between the two passbands also remains above 30dB. Furthermore, the in-band rejection... S 11 Always better than -16dB S 21 It consistently outperforms by -0.08dB. Furthermore, it offers a wide adjustable range for both low-frequency and high-frequency passbands. Overall, this filter not only maintains good engineering potential but also boasts excellent performance.

[0041] This invention relates to a fully automatic, reconfigurable, compact dual-passband filter, which offers several significant advantages. First, its fully automatic reconfigurable function allows for precise control of the adjustment circuit performance via external power-up, enabling independent adjustment of both passbands. Compared to traditional mechanically adjusted filters, this reduces manual intervention and allows for rapid frequency band reconfiguration, greatly enhancing system flexibility and convenience. Second, its compact design employing a multimode resonator structure significantly reduces size and weight, making it suitable for space-constrained applications such as small communication devices, mobile terminals, and portable devices. Third, this filter can generate transmission zeros outside multiple frequency bands, providing excellent passband performance, selectivity, and out-of-band rejection, effectively suppressing interference from other frequency bands and thus improving the stability and efficiency of the communication system. Furthermore, by adjusting the varactor diode between the feed line and the resonator, the passband stability of the filter is ensured under different environmental conditions, avoiding frequency drift or interference fluctuations, significantly improving system reliability and stability, and ensuring long-term stable operation.

[0042] This invention discloses a fully automatic reconfigurable compact dual-passband filter, designed to improve system flexibility and performance through fully automatic electronic control adjustment, addressing shortcomings in existing technologies. The dual-passband filter of this invention features fully automatic reconfigurability, enabling precise control of the adjustment circuit performance via external power supply and independent adjustment of both passbands. Furthermore, compared to traditional mechanically adjustable reconfigurable filters, it reduces manual intervention, allowing for rapid frequency band reconfiguration, thus enhancing system flexibility and convenience. Employing a multimode resonator structure, it achieves a compact design, significantly reducing size and weight, making it suitable for space-constrained applications such as small communication devices, mobile terminals, and portable devices. The filter can generate transmission zeros outside multiple frequency bands, providing excellent passband performance, selectivity, and out-of-band rejection, effectively suppressing interference from other frequency bands and further improving the stability and efficiency of the communication system. By adjusting the varactor diode between the feeder and the resonator, the passband stability of the filter is ensured under different environmental conditions, preventing frequency drift or interference fluctuations from causing system failure, thereby improving system reliability and stability and ensuring long-term reliable operation.

[0043] The embodiments of the present invention have been described in detail above. Specific examples have been used in this document to illustrate the principles of the present invention. The implementation methods have been described. The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A fully automatic, reconfigurable, compact dual-passband filter, characterized in that: It includes input coupling and matching circuit, low-frequency dual-mode resonant circuit, high-frequency dual-mode resonant circuit, intermediate coupling circuit, output coupling and matching circuit, and DC bias circuit; The output of the input coupling and matching circuit is divided into two paths. One path is connected to the input coupling section of the low-frequency dual-mode resonant circuit through interpolation coupling. The other path is connected to the intermediate coupling circuit through the fourth DC blocking capacitor (7). The intermediate coupling circuit includes a second microstrip feed line (8) and a third microstrip feed line (14), with the second microstrip feed line (8) connected to the third microstrip feed line (14) by interpolation coupling. The second microstrip feed line (8) is connected to the input coupling section of the low-frequency dual-mode resonant circuit and the input coupling section of the high-frequency dual-mode resonant circuit respectively by interpolation coupling. The third microstrip feed line (14) is connected to the output coupling section of the high-frequency dual-mode resonant circuit by interpolation coupling. The third microstrip feed line (14) is also connected to the output coupling and matching circuit through the fifth DC blocking capacitor (15); The output coupling and matching circuit is connected to the output coupling section of the low-frequency dual-mode resonant circuit via interpolation coupling. The multiple DC power-on terminals are respectively connected to the varactor diodes contained in the input coupling and matching circuit, the low-frequency dual-mode resonant circuit, the high-frequency dual-mode resonant circuit, the intermediate coupling circuit, and the output coupling and matching circuit, and are used to independently provide tuning voltage.

2. The fully automatic, reconfigurable, compact dual-passband filter as described in claim 1, characterized in that: The input coupling and matching circuit, the low-frequency dual-mode resonant circuit, the high-frequency dual-mode resonant circuit, the intermediate coupling circuit, and the output coupling and matching circuit together constitute a symmetrical coupling structure. The interdigitated coupling method includes interdigitated microstrip line structure and auxiliary branch interdigitated microstrip line structure.

3. The fully automatic, reconfigurable, compact dual-passband filter as described in claim 1, characterized in that: The input coupling and matching circuit, the low-frequency dual-mode resonant circuit, the high-frequency dual-mode resonant circuit, the intermediate coupling circuit, the output coupling and matching circuit, and the DC bias circuit are all disposed on the metal layer of the dielectric substrate (22) and are all implemented with a microstrip line structure.

4. The fully automatic, reconfigurable, compact dual-passband filter as described in claim 1, characterized in that: The low-frequency dual-mode resonant circuit includes an input coupling section and an output coupling section. The input coupling section of the low-frequency dual-mode resonant circuit includes a first microstrip line structure (9), and the output coupling section of the low-frequency dual-mode resonant circuit includes a second microstrip line structure (13). The high-frequency dual-mode resonant circuit includes an input coupling section and an output coupling section. The input coupling section of the high-frequency dual-mode resonant circuit has a third microstrip line structure (34), and the output coupling section of the high-frequency dual-mode resonant circuit has a fourth microstrip line structure (32).

5. The fully automatic, reconfigurable, compact dual-passband filter as described in claim 4, characterized in that: The input coupling and matching circuit includes an input 50Ω microstrip feed line (1), a third DC blocking capacitor (43), a first microstrip feed line (41), a first varactor diode pad structure (2), a first varactor diode (3), and a third DC power supply terminal (42). The input 50Ω microstrip feed line (1) is connected to the first microstrip feed line (41) through the third DC blocking capacitor (43). The upper left part of the first microstrip feed line (41) is connected to the first varactor diode pad structure (2) through a microstrip high-resistance line. The first varactor diode (3) is connected between the first varactor diode pad structure (2) and the upper left ground terminal (10). The lower part of the first microstrip feed line (41) is connected to the third DC power supply terminal (42) through a high-resistance microstrip line.

6. The fully automatic, reconfigurable, compact dual-passband filter as described in claim 5, characterized in that: The low-frequency dual-mode resonant circuit includes a first microstrip line structure (9), a second microstrip line structure (13) with an output coupling section, a first microstrip block structure (11), a first DC blocking capacitor (4), a second DC blocking capacitor (18), a first DC power-on terminal (6), a second DC power-on terminal (16), a second varactor diode (5), a third varactor diode (17), a left upper ground terminal (10), and a right upper ground terminal (12). The left end of the first microstrip line structure (9) is connected to the first DC power supply terminal (6) via the first DC blocking capacitor (4), and the upper part of the first DC power supply terminal (6) is connected to the upper left ground terminal (10) via the second varactor diode (5); the right side of the first microstrip line structure (9) is connected to the second microstrip line structure (13) via the first microstrip block structure (11), and the upper right part of the first microstrip line structure (9) is directly connected to the upper left ground terminal (10); the right end of the second microstrip line structure (13) is connected to the second DC power supply terminal (16) via the second DC blocking capacitor (18), and the upper part of the second DC power supply terminal (16) is connected to the upper right ground terminal (12) via the third varactor diode (17).

7. The fully automatic, reconfigurable, compact dual-passband filter as described in claim 6, characterized in that: The high-frequency dual-mode resonant circuit includes a third microstrip line structure (34), a fourth microstrip line structure (32), a second microstrip block structure (33), a seventh DC blocking capacitor (37), an eighth DC blocking capacitor (29), a fifth DC power-on terminal (36), a sixth DC power-on terminal (30), a sixth varactor diode (38), a seventh varactor diode (28), a lower left ground terminal (35), and a lower right ground terminal (31). The left end of the third microstrip line structure (34) is connected to the fifth DC power supply terminal (36) via the seventh DC blocking capacitor (37), and the lower part of the fifth DC power supply terminal (36) is connected to the lower left ground terminal (35) via the sixth varactor diode (38); the right side of the third microstrip line structure (34) is connected to the fourth microstrip line structure (32) via the second microstrip block structure (33), and the lower right part of the third microstrip line structure (34) is directly connected to the lower left ground terminal (35); the right end of the fourth microstrip line structure (32) is connected to the sixth DC power supply terminal (30) via the eighth DC blocking capacitor (29), and the lower part of the sixth DC power supply terminal (30) is connected to the lower right ground terminal (31) via the seventh varactor diode (28).

8. The fully automatic, reconfigurable, compact dual-passband filter as described in claim 7, characterized in that: The intermediate coupling circuit includes a second microstrip feed line (8), a third microstrip feed line (14), a fourth DC blocking capacitor (7), a fifth DC blocking capacitor (15), a fourth DC power-on terminal (40), a seventh DC power-on terminal (26), a fifth varactor diode (39), an eighth varactor diode (27), a lower left ground terminal (35), and a lower right ground terminal (31). The second microstrip feed line (8) and the third microstrip feed line (14) are coupled to each other through an interdigitated microstrip line structure. The lower part of the second microstrip feed line (8) is connected to the fourth DC power-on terminal (40) via a high-impedance microstrip line, and the lower part of the fourth DC power-on terminal (40) is connected to the lower left ground terminal (35) via the fifth varactor diode (39). The lower part of the third microstrip feed line (14) is connected to the seventh DC power-on terminal (26) via a high-impedance microstrip line, and the lower part of the seventh DC power-on terminal (26) is connected to the lower right ground terminal (31) via the eighth varactor diode (27).

9. The fully automatic, reconfigurable, compact dual-passband filter as described in claim 8, characterized in that: The output coupling and matching circuit includes a fourth microstrip feed line (25), a sixth DC blocking capacitor (23), an output 50Ω microstrip feed line (21), a second varactor diode pad structure (20), a fourth varactor diode (19), an eighth DC power-on terminal (24), and a right upper ground terminal (12). The right side of the fourth microstrip feed line (25) is connected to the output 50Ω microstrip feed line (21) via the sixth DC blocking capacitor (23); the upper right part of the fourth microstrip feed line (25) is connected to the second varactor diode pad structure (20) via a microstrip high-resistance line, and the second varactor diode pad structure (20) is connected to the upper right ground terminal (12) via the fourth varactor diode (19); the lower part of the fourth microstrip feed line (25) is connected to the eighth DC power supply terminal (24) via a high-resistance microstrip line.

10. The fully automatic, reconfigurable, compact dual-passband filter as described in claim 9, characterized in that: The DC bias circuit includes multiple independent DC power-on terminals, with the specific connections as follows: The first DC power-on terminal (6) and the second DC power-on terminal (16) are respectively connected to the second varactor diode (5) and the third varactor diode (17) in the low-frequency dual-mode resonant circuit, and are used to independently adjust the center frequency of the low-frequency passband. The fifth DC power-on terminal (36) and the sixth DC power-on terminal (30) are respectively connected to the sixth varactor diode (38) and the seventh varactor diode (28) in the high-frequency dual-mode resonant circuit, and are used to independently adjust the center frequency of the high-frequency passband; The third DC power-on terminal (42) and the eighth DC power-on terminal (24) are respectively connected to the first varactor diode (3) in the input coupling and matching circuit and the fourth varactor diode (19) in the output coupling and matching circuit, for controlling the in-band response of the dual passband and compensating for processing errors; The fourth DC power-on terminal (40) and the seventh DC power-on terminal (26) are respectively connected to the fifth varactor diode (39) and the eighth varactor diode (27) in the intermediate coupling circuit to adjust the frequency position of the transmission zero point; All of the DC power terminals are independently powered.

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