A miniaturized filter

Abstract

This invention aims to provide a miniaturized filter, comprising a dielectric substrate, resonator units, and adjustable capacitors. The filter is characterized by: multiple sets of resonator units arranged side-by-side on the dielectric substrate, with gaps between adjacent resonator units; each set of resonator units has an identical structure and is symmetrical; each set of resonator units is loaded with an adjustable capacitor; the left side of the first set of resonator units and the right side of the last set of resonator units are respectively provided with port coupling lines, and each of the two sets of port coupling lines has a port. This invention enables miniaturization while maintaining low return loss, ensuring high-quality signal transmission.

Description

Technical Field

[0001] This utility model relates to the field of microwave radio frequency filter technology, and specifically to a miniaturized filter. Background Technology

[0002] The primary function of a filter is to extract the desired signal within a specific frequency band while effectively suppressing interference outside that band. In integrated circuits, the coordinated operation of active components such as oscillators, frequency multipliers, mixers, and power amplifiers often makes the signal spectrum more complex. Therefore, introducing filters not only helps remove spurious frequency components but also effectively suppresses image frequency interference, thereby significantly improving the stability and reliability of the circuit system. Filters are widely used in radio frequency front-end systems, and their parameters directly affect the overall system performance.

[0003] Microwave filters are crucial components in wireless communication systems, responsible for selecting and filtering signals of different frequencies. Their main technical specifications include insertion loss, return loss, passband width, stopband rejection, and size. Current filters are primarily classified by resonator type: lumped LC filters, surface acoustic wave / bulk acoustic wave / thin-film bulk acoustic wave filters, coaxial line filters, cavity filters, and microstrip line filters. Lumped LC filters have a complete theoretical system and a clear structural design. Their design principles are often used as a reference for other filters. However, they suffer from large size and limited operating frequency. Surface acoustic wave (SAW), bulk acoustic wave (SAW), and thin-film SAW filters achieve electromagnetic wave-to-sound wave conversion through the piezoelectric effect. Utilizing the characteristic that the wavelength of sound waves is significantly shorter than that of electromagnetic waves, they have achieved a breakthrough in reducing device size, featuring small size, light weight, good consistency, and high rectangular coefficient. However, their manufacturing process is complex and costly. Coaxial line filters have a stable structure, high quality factor, and large power capacity, but they are difficult to manufacture at high frequencies and suffer from significant parasitic interference. At low frequencies, they are relatively large. Cavity filters have a robust structure, stable performance, and high Q value. However, because their resonant size is directly related to the waveguide wavelength, they have inherent limitations in miniaturization. Utility Model Content

[0004] In view of the technical problems existing in the background art, the present invention aims to provide a miniaturized filter, including a dielectric substrate, resonator units, and adjustable capacitors, characterized in that: multiple sets of resonator units are arranged side by side on the dielectric substrate, with gaps between adjacent resonator units; each set of resonator units has the same structure and is symmetrical; each set of resonator units is loaded with an adjustable capacitor, and the left side of the first set of resonator units and the right side of the last set of resonator units are respectively provided with port coupling lines coupled to them, and ports are provided on the two sets of port coupling lines respectively.

[0005] The resonator unit includes a metal strip A and an adjustable capacitor. The two ends of the metal strip A are arranged opposite each other and are connected to one end of the adjustable capacitor.

[0006] The metal strip A is symmetrically arranged with the center line of the adjustable capacitor as the boundary, and includes a vertical segment A, a vertical segment B, and a multi-stage bending segment. The multi-stage bending segment is located at the upper and lower parts of the resonator unit, and the adjustable capacitor is located at the top of the upper multi-stage bending segment. The left and right sides of the upper and lower multi-stage bending segments are connected by parallel vertical segments A and B, respectively, and are symmetrically arranged on the upper and lower sides of vertical segments A and B. Each bending unit of the multi-stage bending segment consists of a bending segment and two connecting segments. Adjacent bending segments are connected by their respective connecting segments to form a continuous bending path. The open end A of the vertical segment A and the open end B of the vertical segment B are respectively connected to the connecting segments of the multi-stage bending segment.

[0007] It also includes metal strips B and C. Metal strips B are evenly spaced on the vertical segment A. Metal strips B are arranged perpendicular to the vertical segment A in the left-right direction, and the right end of metal strip B extends to the right near the vertical segment B. Metal strips C are evenly spaced on the vertical segment B. Metal strips C are arranged perpendicular to the vertical segment B in the left-right direction, and the left end of metal strip C extends to the left near the vertical segment A. Metal strips B and metal strip C are staggered in the up-down direction.

[0008] The distance between the right end of metal strip B and vertical segment B is 0.03-0.05mm, and the distance between the right end of metal strip C and vertical segment A is 0.03-0.05mm.

[0009] The lengths of the first and last sets of resonator units are slightly smaller than the lengths of the other sets of resonator units.

[0010] The lengths of the first and last resonator units are 41.18-41.38 mm; the lengths of the other resonator units are 41-24-41.44 mm.

[0011] The port uses 50Ω impedance matching.

[0012] The linewidth of each resonator unit is 0.07-0.09 mm.

[0013] The adjustable capacitors of the first and last resonator units have a capacitance of 32-34pF, while the adjustable capacitors of the remaining resonator units have a capacitance of 29-31pF.

[0014] The beneficial effects of this utility model are as follows:

[0015] The miniaturized filter of this application, through the research of a novel microstrip line design structure, adopts a hybrid form of lumped parameter elements and microstrip lines, and employs an interdigital coupling structure, a loaded spiral open-circuit stub, and a zigzag resonator design, which can effectively reduce the size of the filter while ensuring its high performance. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the miniaturized superconducting bandpass filter of this utility model;

[0017] Figure 2 This is a simulation diagram of the S-parameters of the miniaturized superconducting bandpass filter of this invention;

[0018] Figure 3 This utility model relates to a miniaturized superconducting bandpass filter S. 21 Simulation diagram of group delay parameters.

[0019] The names and numbers of the parts in the diagram are as follows:

[0020] 1 is a resonator unit, 2 is an adjustable capacitor, 3 is a port, 4 is metal strip A, 5 is metal strip B, 6 is a bent section, 7 is a connecting section, 8 is a port coupling line, 9 is a vertical section A, 10 is a multi-stage bent section, 11 is an open end A, 12 is a metal strip C, 13 is a vertical section B, and 14 is an open end B. Detailed Implementation

[0021] The following description, in conjunction with the accompanying drawings, details the implementation methods and embodiments of this utility model and their working processes. Example 1

[0022] Referring to the accompanying drawings, a miniaturized filter in this embodiment includes a dielectric substrate, resonator units 1, and adjustable capacitors 2. The filter is characterized by: multiple sets of resonator units 1 arranged side-by-side on the dielectric substrate, with gaps between adjacent resonator units 1; each set of resonator units 1 has the same structure and is symmetrical; each set of resonator units 1 is loaded with an adjustable capacitor 2; the left side of the first set of resonator units 1 and the right side of the last set of resonator units 1 are respectively provided with port coupling lines 8, and each of the two sets of port coupling lines 8 has a port 3. The port coupling lines 8 are used to enhance the coupling between the input / output terminals and the resonator.

[0023] The resonator unit 1 includes a metal strip A4 and an adjustable capacitor 2. The two ends of the metal strip A4 are arranged opposite to each other and are respectively connected to one end of the adjustable capacitor 2.

[0024] The metal strip A4 is symmetrically arranged with the center line of the adjustable capacitor 2 as the boundary, and includes a vertical segment A9, a vertical segment B13, and a multi-stage bending segment 10. The multi-stage bending segment 10 is located at the upper and lower parts of the resonator unit 1, and the adjustable capacitor 2 is located at the top of the upper multi-stage bending segment 10. The left and right sides of the upper and lower multi-stage bending segments 10 are connected by parallel vertical segments A9 and B13, respectively, and are symmetrically arranged on the upper and lower sides of the vertical segments A9 and B13. Each bending unit of the multi-stage bending segment 10 consists of a bending segment 6 and two connecting segments 7. Adjacent bending segments 6 are connected by their respective connecting segments 7 to form a continuous bending path. The open end A11 of the vertical segment A9 and the open end B14 of the vertical segment B13 are respectively connected to the connecting segments 7 of the multi-stage bending segment 10.

[0025] It also includes metal strips B5 and C12. Metal strips B5 are evenly spaced on the vertical segment A9, perpendicular to the vertical segment A9 in the left-right direction, with the right end of metal strip B5 extending to the right near the vertical segment B13. Metal strips C12 are evenly spaced on the vertical segment B13, perpendicular to the vertical segment B13 in the left-right direction, with the left end of metal strip C12 extending to the left near the vertical segment A9. The metal strips B5 and C12 are staggered in the vertical direction. The use of an interdigital coupling structure, a loaded spiral open-circuit stub, and a zigzag design effectively reduces the filter's size while ensuring high performance.

[0026] The distance between the right end of metal strip B5 and vertical section B13 is 0.04mm, and the distance between the right end of metal strip C12 and vertical section A9 is 0.04mm.

[0027] The lengths of the first and last resonator units 1 are slightly smaller than the lengths of the other resonator units 1. Due to the influence of external coupling, the resonant frequencies of the first and last resonator units 1 are slightly reduced, so their design size is smaller than that of the other resonators in order to keep all resonators frequency synchronized.

[0028] The length of the first group of resonator units 1 and the last group of resonator units 1 is 41.28 mm; the length of the other groups of resonator units 1 is 41.34 mm.

[0029] Port 3 uses 50Ω impedance matching.

[0030] The linewidth of each resonator unit 1 is 0.08 mm.

[0031] The adjustable capacitor 2 of the first group of resonator units 1 and the last group of resonator units 1 has a capacitance of 33pF, while the adjustable capacitor 2 of the remaining groups of resonator units 1 has a capacitance of 30pF.

[0032] The metal strips A4, B5, C12 and port 3 are all made of copper wire. Example 2

[0033] Simulation experiments were conducted using the miniaturized filter from Example 1.

[0034] In the Sonnet 17 system, a suitable dielectric substrate is selected, and the center frequency is designed to be... f 0 = 1.602 GHz, with a relative bandwidth FBW of 1.25%. The dashed line represents the S21 return loss, and the solid line represents the S11 insertion loss. This is achieved within the passband range of 1.592 GHz - 1.612 GHz. 11 |<-20.94dB, |S 21 The loss is -0.01dB, achieving near-lossless transmission performance.

[0035] The working principle of this utility model is as follows:

[0036] This filter is a microstrip line filter, consisting of four sets of resonator units arranged side by side on a dielectric substrate. Each set of resonator units has the same structure and is symmetrical. The resonator units are coupled to each other through a gap and each set of adjustable capacitors is loaded. The left side of the first set of resonator units and the right side of the last set of resonator units are respectively provided with port coupling lines. Port coupling lines are provided on the two sets of port coupling lines to enhance the coupling between the input / output terminals and the resonators.

[0037] The microstrip line filter is electrically fed from both ports. Energy is mainly transferred between the resonators through magnetic coupling. Due to the influence of external coupling, the resonant frequencies of the first and last resonators are slightly reduced. Therefore, the design size of the first and last resonators is smaller than that of the other resonators to keep all resonators frequency synchronized. By setting the adjustable capacitor value of the first and last resonator units to 33pF and the adjustable capacitor value of the remaining resonator units to 30pF, and matching the distance and geometry between the microstrip lines, a hybrid structure of lumped parameter elements and microstrip lines can be adopted. This allows the filter size to be significantly reduced while achieving good return loss and generating a zero at low frequencies, resulting in high frequency selectivity.

Claims

1. A miniaturized filter comprising a dielectric substrate, a resonator unit (1), an adjustable capacitance (2), characterized in that: The resonator unit (1) is provided in multiple groups and arranged side by side on the dielectric substrate, with gaps between adjacent resonator units (1); each group of resonator units (1) has the same structure and is a left-right symmetrical structure; each group of resonator units (1) is loaded with a set of adjustable capacitors (2), and the left side of the first group of resonator units (1) and the right side of the last group of resonator units (1) are respectively provided with port coupling lines (8) coupled to them, and ports (3) are respectively provided on the two sets of port coupling lines (8).

2. The miniaturized filter according to claim 1, characterized in that: The resonator unit (1) includes a metal strip A (4) and an adjustable capacitor (2). The two ends of the metal strip A (4) are arranged opposite to each other and are respectively connected to one end of the adjustable capacitor (2).

3. The miniaturized filter according to claim 2, characterized in that: The metal strip A (4) is symmetrically arranged with the center line of the adjustable capacitor (2) as the boundary, including a vertical section A (9), a vertical section B (13), and a multi-stage bending section (10). The multi-stage bending section (10) is located at the upper and lower parts of the resonator unit (1), and the adjustable capacitor (2) is located at the top of the upper multi-stage bending section (10). The left and right sides of the upper and lower multi-stage bending sections (10) are connected by parallel vertical sections A (9) and B (13), respectively. The segments are symmetrically arranged on the upper and lower sides of the vertical segments A (9) and B (13), respectively; each bending unit of the multi-level bending segment (10) consists of a bending segment (6) and two connecting segments (7); adjacent bending segments (6) are connected by their respective connecting segments (7) to form a continuous bending path; the open end A (11) of the vertical segment A (9) and the open end B (14) of the vertical segment B (13) are respectively connected to the connecting segments (7) of the multi-level bending segment (10).

4. The miniaturized filter according to claim 3, characterized in that: It also includes metal strip B (5) and metal strip C (12). Metal strip B (5) is evenly spaced on the vertical segment A (9). The metal strip B (5) is set perpendicular to the vertical segment A (9) in the left-right direction. The right end of the metal strip B (5) extends to the right and is close to the vertical segment B (13). Metal strip C (12) is evenly spaced on the vertical segment B (13). The metal strip C (12) is set perpendicular to the vertical segment B (13) in the left-right direction. The left end of the metal strip C (12) extends to the left and is close to the vertical segment A (9). The metal strip B (5) and metal strip C (12) are staggered in the up-down direction.

5. The miniaturized filter of claim 1, wherein: The distance between the right end of metal strip B (5) and vertical segment B (13) is 0.03-0.05 mm, and the distance between the right end of metal strip C (12) and vertical segment A (9) is 0.03-0.05 mm.

6. The miniaturized filter of claim 1, wherein: The lengths of the first group of resonator units (1) and the last group of resonator units (1) are slightly smaller than the lengths of the other groups of resonator units (1).

7. The miniaturized filter according to claim 6, characterized in that: The lengths of the first group of resonator units (1) and the last group of resonator units (1) are 41.18-41.38 mm; the lengths of the other groups of resonator units (1) are 41-24-41.44 mm.

8. The miniaturized filter according to claim 1, characterized in that: The port (3) is impedance matched with 50Ω.

9. The miniaturized filter according to claim 1, characterized in that: The linewidth of each resonator unit (1) is 0.07-0.09 mm.

10. The miniaturized filter according to claim 1, characterized in that: The adjustable capacitors (2) of the first group of resonator units (1) and the last group of resonator units (1) have a capacitance of 32-34pF, while the adjustable capacitors (2) of the remaining groups of resonator units (1) have a capacitance of 29-31pF.

Images