A miniaturized wide-stopband bandpass filter with inductive coupling

Abstract

The present invention discloses a miniaturized wide-stopband bandpass filter with inductive coupling, comprising components such as a reference metal ground, a substrate, a feeder, a spiral inductor, a chip capacitor, a ground pad, a metallized through-hole, and a gold wire bond. In filter design, a large number of inductive components will cause unnecessary parasitic effects, thereby leading to communication system security issues. At the same time, it will also increase the complexity of design and debugging for technicians. The present invention introduces inductive coupling between two parallel series LC resonators, replacing the two inductors with one coupled inductor, reducing the number of inductive components, thereby avoiding parasitic effects caused by the inductors, and facilitating design and debugging work for technicians. The filter of the present invention provides low insertion loss in the passband and large signal attenuation in the stopband. By adopting coupled inductors, the size of the filter is further reduced, and it has the characteristics of miniaturization, lightness, and high integration.

Description

Technical Field

[0001] The present invention belongs to the field of microwave technology and electronic engineering applications, and in particular relates to a miniaturized wide-stopband bandpass filter with inductive coupling. Background Art

[0002] In recent years, the development of communications technology has profoundly impacted every aspect of our lives. In particular, with the widespread commercialization of fifth-generation mobile communications (5G) technology, the growing popularity of end products such as driverless cars and Internet of Things (IoT) platforms has led to higher demands on communication systems. To provide consumers with an ultimate user experience, communications equipment must incorporate miniaturization and lightweighting into its design while ensuring excellent performance. Filters, as the cornerstone of communication systems, provide low insertion loss in the passband and high signal attenuation in the stopband, significantly impacting the performance of the entire communication system. Conventional design methods, such as flattest response filters, equiripple response filters, and elliptic function filters, increase the number of components as the order increases. This not only complicates design and debugging but can also lead to parasitic effects in the filters, posing challenges to the security of communication systems.

[0003] Therefore, optimizing the topology has become a key issue for technicians in conventional filter design. By introducing inductive coupling into two parallel series LC resonators, the filter model design can be simplified, miniaturized, and lightweight while maintaining performance, meeting the security requirements of communication systems. Summary of the Invention

[0004] Purpose of the invention:

[0005] The object of the present invention is to provide a miniaturized wide stopband bandpass filter with inductive coupling, which is a miniaturized high-performance bandpass filter with a wide stopband.

[0006] Technical solution:

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] A miniaturized wide-stopband bandpass filter with inductive coupling, comprising a reference metal ground, a substrate, a first feed line, a second feed line, a spiral inductor, a chip capacitor, a ground pad, a metallized through hole, and gold wire bonding; the filter has three parts, including a first part, a second part, and a third part, wherein the first part, the second part, and the third part are sequentially placed between the first feed line and the second feed line;

[0009] The first part includes a first capacitor connected in series, a second capacitor and a third capacitor connected in parallel and grounded in series, and a fourth capacitor and a first inductor connected in series; the second part includes a second inductor and a fifth capacitor connected in parallel and grounded in series, and a third inductor and a sixth capacitor connected in parallel and grounded in series, wherein the second inductor and the third inductor are coupled to each other; the third part includes a fourth inductor and a seventh capacitor connected in series, an eighth capacitor and a ninth capacitor connected in parallel and grounded in series, and a tenth capacitor connected in series.

[0010] Furthermore, in the filter, the first inductor and the fourth inductor are spiral inductors of the same shape, the second inductor and the third inductor are coupled inductors, and the inductors are all planar spiral inductors.

[0011] Furthermore, the second inductor is connected by gold wire bonding, and the third inductor is directly connected. The tail ends of the second inductor and the third inductor are connected, which further reduces the size of the filter.

[0012] Furthermore, the first capacitor, the second capacitor, the third capacitor, the fourth capacitor, the fifth capacitor, the sixth capacitor, the seventh capacitor, the eighth capacitor, the ninth capacitor, and the tenth capacitor are all chip capacitors.

[0013] Furthermore, the filter adopts an integrated passive device process, but is not limited to the integrated passive device process, and may also adopt a low-temperature co-fired ceramic process, etc.

[0014] Beneficial effects

[0015] The present invention provides a miniaturized wide-stopband bandpass filter with inductive coupling. Inductive coupling is introduced between parallel series LC resonators, replacing two inductors with a single coupled inductor. This reduces the number of inductive components, thereby avoiding parasitic effects caused by the inductors and facilitating design and debugging by technical personnel. The filter of the present invention provides low insertion loss within the passband and high signal attenuation within the stopband. Its stopband is broadband and has three transmission poles within the passband, a zero in the lower stopband, and a zero in the upper stopband. Furthermore, the use of coupled inductors further reduces the size of the filter, resulting in miniaturization, lightweighting, and high integration. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A top view of a miniaturized wide-stopband bandpass filter with inductive coupling;

[0017] Figure 2 The overall structure diagram of a miniaturized wide-stopband bandpass filter with inductive coupling is shown;

[0018] Figure 3 A circuit diagram of a miniaturized wide-stopband bandpass filter with inductive coupling;

[0019] Figure 4 This is a performance comparison chart of a miniaturized wide-stopband bandpass filter with inductive coupling;

[0020] In the figure: 1. First feed line, 2. First capacitor, 3. Connecting line, 4. Fourth capacitor, 5 Connecting line, 6. First inductor, 7. Gold wire bonding, 8. Connecting line, 9. Gold wire bonding, 10. Fourth inductor, 11. Connecting line, 12. Seventh capacitor, 13. Connecting line, 14. Tenth capacitor, 15. Second feed line, 16. Connecting line, 17. Eighth capacitor, 18. Connecting line, 19. Ninth capacitor, 20. Connecting line, 21. Metallized through hole, 22. Ground pad, 23. Ground pad, 24. Metallized through hole, 25. Connecting line, 26. 6. Sixth capacitor, 27. Connecting wire, 28. Gold bond, 29. Third inductor, 30. Gold bond, 31. Connecting wire, 32. Second inductor, 33. Gold bond, 34. Connecting wire, 35. Fifth capacitor, 36. Connecting wire, 37. Plated through hole, 38. Ground pad, 39. Ground pad, 40. Plated through hole, 41. Connecting wire, 42. Third capacitor, 43. Connecting wire, 44. Second capacitor, 45. Connecting wire, 46. Reference metal ground, 47. Substrate, A. Part 1, B. Part 2, C. Part 3 DETAILED DESCRIPTION

[0021] The following examples may enable those skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way.

[0022] The present invention provides a miniaturized wide stopband bandpass filter with inductive coupling, comprising a reference metal ground 46, a substrate 47, a first feed line 1, a second feed line 15, a spiral inductor 6, a chip capacitor 2, a ground pad 22, a metallized through hole 24 and a gold wire bond 7;

[0023] Figure 1 FIG is a top view of a miniaturized wide stopband bandpass filter with inductive coupling according to an embodiment of the present invention; see Figure 1 , the filter has three parts, including a first part A, a second part B and a third part C, and the first part A, the second part B and the third part C are sequentially placed between the first feeder 1 and the second feeder 15;

[0024] The first part A comprises a first capacitor 2 connected in series, a second capacitor 44 and a third capacitor 42 connected in parallel and grounded in series, and a fourth capacitor 4 and a first inductor 6 connected in series;

[0025] One end of the first capacitor 2 is connected to the second capacitor 44 and the fourth capacitor 4 by using a connecting line 45 and a connecting line 3 , and the other end is connected to the first feeder 1 .

[0026] One end of the third capacitor 42 is connected to the second capacitor 44 via a connecting line 43, and the other end is grounded via a connecting line 41 (39, 40);

[0027] The fourth capacitor 4 and the first inductor 6 are connected by a connecting line 5;

[0028] The first inductor 6 and the connecting wire 8 are connected by gold wire bonding 7;

[0029] The second part B includes a second inductor 32 and a fifth capacitor 35 connected in parallel and grounded in series, and a third inductor 29 and a sixth capacitor 26 connected in parallel and grounded in series, wherein the second inductor 32 and the third inductor 29 are coupled to each other;

[0030] The second inductor 32 is connected by gold wire bonding 30, and the third inductor 29 is directly connected by a connecting wire 31. The tail ends of the second inductor 32 and the third inductor 29 are connected to the connecting wire 8;

[0031] The second inductor 32 and the connecting wire 34 are connected by gold wire bonding 33;

[0032] One end of the fifth capacitor 35 is connected to the connection line 34, and the other end is connected to the ground 37, 38 via the connection line 36;

[0033] The third inductor 29 and the connecting line 27 are connected by gold wire bonding 28;

[0034] One end of the sixth capacitor 26 is connected to the connection line 27, and the other end is connected to the ground 23, 24 via the connection line 25;

[0035] The third portion C includes a fourth inductor 10 and a seventh capacitor 12 connected in series, an eighth capacitor 17 and a ninth capacitor 19 connected in parallel and connected in series to ground, and a tenth capacitor 14 connected in series;

[0036] The fourth inductor 10 and the seventh capacitor 12 are connected by a connecting line 11;

[0037] One end of the tenth capacitor 14 is connected to the eighth capacitor 17 and the seventh capacitor 12 via a connecting line 16 and a connecting line 13 , and the other end is connected to the second feed line 15 .

[0038] One end of the ninth capacitor 19 is connected to the eighth capacitor 17 via a connection line 18 , and the other end is connected to grounds 21 and 22 via a connection line 20 ;

[0039] The fourth inductor 10 and the connecting wire 8 are connected by gold wire bonding 9;

[0040] The first inductor 6 and the fourth inductor 10 are spiral inductors of the same shape, and the second inductor 32 and the third inductor 29 are coupled inductors;

[0041] The first capacitor 2 , the second capacitor 44 , the third capacitor 42 , the fourth capacitor 4 , the fifth capacitor 35 , the sixth capacitor 26 , the seventh capacitor 12 , the eighth capacitor 17 , the ninth capacitor 19 , and the tenth capacitor 14 are all chip capacitors.

[0042] The grounding includes grounding pads 39 , 38 , 23 , 22 , metallized through holes 40 , 37 , 24 , 21 , and a reference metal ground 46 .

[0043] The filter design method of the present invention is as follows:

[0044] 1) First, create the following in the circuit simulation software ADS Figure 3 In the filter circuit shown, G1 is the first feeder 1, C1 is the first capacitor 2, C2 is the second capacitor 44, C3 is the third capacitor 42, C4 is the fourth capacitor 4, the inductor connected to C4 is the first inductor 6, C5 is the fifth capacitor 35, the inductor connected to C5 is the second inductor 32, C6 is the sixth capacitor 26, the inductor connected to C6 is the third inductor 29, C7 is the seventh capacitor 12, the inductor connected to C7 is the fourth inductor 10, C8 is the eighth capacitor 17, C9 is the ninth capacitor 19, C10 is the tenth capacitor 14, and G2 is the second feeder 15. The second inductor 32 and the third inductor 29 are coupled to each other, and the coupling coefficient is determined by the distance between the second and third inductors. After setting the distance, the component parameter values ​​are adjusted so that the operating frequency of the filter circuit is 2.5 GHz.

[0045] 2) Then, in the electromagnetic simulation software HFSS, the structure shown in the figure is created, using a planar spiral inductor and a chip capacitor. Based on the inductance values ​​in the circuit, Q3D is used to determine the physical dimensions of the first inductor 6, the second inductor 32, the third inductor 29, and the fourth inductor 10. Based on the capacitance values ​​in the circuit, the appropriate chip capacitor values ​​are selected.

[0046] 3) Finally, according to the trend in the circuit diagram, inductor L2, capacitor C5, capacitor C6, and coupling coefficient determine the center frequency and operating bandwidth. Capacitor C5 controls the zero point TZ1 at the out-of-band low frequency, and capacitor C6 controls the zero point TZ2 at the out-of-band high frequency. Capacitors C1, C2, C3, C4, inductor L1, capacitor C7, C8, C9, and C10 control the in-band poles. Adjust the corresponding component values ​​in HFSS to obtain a performance comparison chart, as shown below. Figure 4 shown.

[0047] From the simulation results, it can be seen that the filter circuit has the characteristics of wide stopband, with a center frequency f0 = 2.5GHz, a passband range of 2.15GHz-2.85GHz, a return loss in the passband of -20dB, a relative bandwidth of 28%, an insertion loss in the passband of less than 0.9dB, and an out-of-band suppression of more than 18.4dB from 3.3Ghz to 10Ghz, and more than 24.1dB from 0Ghz to 1.73Ghz.

[0048] The substrate of this embodiment is a semiconductor substrate. Figure 2 . Copper is used for inductors, gold wire bonding, and reference metal ground. The size of the filter is 5mm×1.925mm. The filter circuit of the present invention has a wide stopband characteristic and uses coupled inductors, which can effectively save the area occupied by the device and meet the current needs of miniaturization, high integration, and lightweight.

[0049] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions based on the principles of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, various improvements and modifications that do not depart from the principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A miniaturized wide-stopband bandpass filter with inductive coupling, characterized in that: It includes a reference metal ground (46), a substrate (47), a first feed line (1), a second feed line (15), a spiral inductor, a chip capacitor (2), a ground pad (22), a metallized through hole (24) and a gold wire bond (7); The filter has three parts, including a first part (A), a second part (B) and a third part (C), and the first part (A), the second part (B) and the third part (C) are sequentially placed between the first feeder (1) and the second feeder (15); The first part (A) comprises a first capacitor (2) connected in series, a second capacitor (44) and a third capacitor (42) connected in parallel and grounded in series, and a fourth capacitor (4) and a first inductor (6) connected in series; One end of the first capacitor (2) is connected to the second capacitor (44) and the fourth capacitor (4) respectively by connecting wires, and the other end is connected to the first feeder (1); One end of the third capacitor (42) is connected to the second capacitor (44) via a connecting line (43), and the other end is grounded via a connecting line (41); The fourth capacitor (4) and the first inductor (6) are connected by a connecting line (5); The first inductor (6) and the connecting wire (8) are connected by gold wire bonding (7); The second portion (B) includes a second inductor (32) and a fifth capacitor (35) connected in parallel and connected in series to ground, and a third inductor (29) and a sixth capacitor (26) connected in parallel and connected in series to ground, wherein the second inductor (32) and the third inductor (29) are coupled to each other; The second inductor (32) is connected by gold wire bonding (30), the third inductor (29) is directly connected by a connecting wire (31), and the tail ends of the second inductor (32) and the third inductor (29) are connected to the connecting wire (8); The second inductor (32) and the connecting line (34) are connected by gold wire bonding (33); One end of the fifth capacitor (35) is connected to the connecting line (34), and the other end is grounded via the connecting line (36); The third inductor (29) and the connecting line (27) are connected by gold wire bonding (28); One end of the sixth capacitor (26) is connected to the connecting line (27), and the other end is grounded via the connecting line (25); The third part (C) comprises a fourth inductor (10) and a seventh capacitor (12) connected in series, an eighth capacitor (17) and a ninth capacitor (19) connected in parallel and grounded in series, and a tenth capacitor (14) connected in series; The fourth inductor (10) and the seventh capacitor (12) are connected by a connecting line (11); One end of the tenth capacitor (14) is connected to the eighth capacitor (17) and the seventh capacitor (12) respectively by connecting wires, and the other end is connected to the second feeder (15); One end of the ninth capacitor (19) is connected to the eighth capacitor (17) via a connecting line (18), and the other end is grounded via a connecting line (20); The fourth inductor (10) and the connecting line (8) are connected by gold wire bonding (9).

2. The miniaturized wide-stopband bandpass filter with inductive coupling according to claim 1, characterized in that: The first inductor (6) and the fourth inductor (10) are spiral inductors of the same shape, and the second inductor (32) and the third inductor (29) are coupled inductors.

3. The miniaturized wide-stopband bandpass filter with inductive coupling according to claim 1, characterized in that: The first capacitor (2), the second capacitor (44), the third capacitor (42), the fourth capacitor (4), the fifth capacitor (35), the sixth capacitor (26), the seventh capacitor (12), the eighth capacitor (17), the ninth capacitor (19), and the tenth capacitor (14) are all chip capacitors.

4. The miniaturized wide-stopband bandpass filter with inductive coupling according to claim 1, characterized in that: The grounding includes grounding pads (39, 38, 23, 22), metallized through holes (40, 37, 24, 21), and a reference metal ground (46).

5. The miniaturized wide-stopband bandpass filter with inductive coupling according to claim 1, characterized in that: The filter adopts integrated passive device technology.

6. The miniaturized wide-stopband bandpass filter with inductive coupling according to claim 1, characterized in that: The filter adopts low temperature co-fired ceramic technology.

Images