CN109950670B

CN109950670B - LTCC-based double-end open-circuit coupling line loading stub ultra-wideband filter

Info

Publication number: CN109950670B
Application number: CN201910135325.3A
Authority: CN
Inventors: 常钰敏; 方洁; 赵子豪; 杨冕; 戴永胜
Original assignee: Nanjing University of Science and Technology
Current assignee: Nanjing University of Science and Technology
Priority date: 2019-02-22
Filing date: 2019-02-22
Publication date: 2020-11-17
Anticipated expiration: 2039-02-22
Also published as: CN109950670A

Abstract

The invention relates to a double-end open-circuit coupling line loading stub ultra-wideband filter based on LTCC (low temperature co-fired ceramic), which belongs to the technical field of microwave, wherein the filter is based on the advantage that LTCC can be closely distributed, and the ultra-wideband filter is successfully realized by utilizing a way that a stub is loaded at the input/output tail end of a three-level wide-edge strong coupling line; the ultra-wideband filter realizes three-dimensional integration by using a low temperature co-fired ceramic (LTCC) process technology, has the advantages of ultra-wideband, extremely low loss, compact structure, small volume, good electrical property, high integration, high yield, low expansion coefficient and the like, and has good application prospect in the fields of military satellite communication systems, radar systems, medical treatment and the like with higher requirements on temperature stability.

Description

LTCC-based double-end open-circuit coupling line loading stub ultra-wideband filter

Technical Field

The invention belongs to the technical field of microwaves, and particularly relates to a double-end open-circuit coupling line loading stub ultra-wideband filter based on LTCC.

Background

The filter is one of the key devices of passive devices in various communication systems, and has the functions of protecting useful signals, filtering useless signals and providing normal work of the system. With the continuous extension of communication technology, modern filters are updating in the direction of smaller size, higher performance, lower cost, and more convenient for mass production. Ultra-wideband technology was originally applied in the military field, with the most common definition of ultra-wideband being derived from ultra-wideband radar systems. How to enable the LTCC ultra-wideband filter to have a wider stop band, lower loss and smaller volume is a research focus of current researchers. The defected ground structure is characterized in that a specific pattern is carved on the grounding plate to change the distributed capacitance distributed inductance of the transmission line on the grounding surface, so that the transmission line on the defected ground has certain band stop or slow wave characteristics, and the transmission of signals in a specific frequency band can be inhibited.

The Low Temperature Co-fired Ceramic (LTCC) process technology is a new integration technology of passive devices, and the passive devices can be miniaturized through a multilayer process. LTCC technology uses ceramics with specific dielectric constant as a medium, and makes them into ceramic substrates and laminates them into desired circuits or modules. The microwave/millimeter wave packaging structure is mainly applied to three directions of a high-density integration technology, a high-power module and a microwave/millimeter wave assembly, and main devices comprise an LTCC element, an LTCC functional device, an LTCC packaging substrate, an LTCC integrated module and the like. The whole system integrated by the obtained final product, namely the passive device or the active passive device, has the advantages of small volume, stable performance, cost advantage in batch production and the like, has wide application prospect, and has great research value.

Disclosure of Invention

The invention aims to provide a double-end open-circuit coupling line loading stub ultra-wideband filter based on LTCC (low temperature co-fired ceramic), which is realized by a three-dimensional integration technology of LTCC and has the advantages of ultra-wideband, extremely low loss, compact structure, small volume, good electrical property, high integration, high yield, low expansion coefficient and the like.

The technical scheme for realizing the purpose of the invention is as follows: a double-end open-circuit coupling line loading stub ultra-wideband filter based on LTCC comprises an input port, an output port, a first section of folding coupling line, a second section of folding coupling line, a third section of folding coupling line, a fourth section of folding coupling line, a fifth section of folding coupling line, a sixth section of folding coupling line, a first section of grounding folding coupling line, a second section of grounding folding coupling line, a rear side grounding end, a front side grounding end, a bottom grounding layer, a left side defected ground structure, a center defected ground structure and a right side defected ground structure; the input port and the output port characteristic impedance are both 50 ohms;

the first section of folding coupling line is identical to the sixth section of folding coupling line in structure, the second section of folding coupling line is identical to the fifth section of folding coupling line in structure, the third section of folding coupling line is identical to the fourth section of folding coupling line in structure, the first section of grounding folding coupling line is identical to the second section of grounding folding coupling line in structure, and the left side defected ground structure is identical to the right side defected ground structure; the folded coupling lines are arranged on the first layer, the folded coupling lines are arranged on the second layer, the folded coupling lines are arranged on the fourth layer, the folded coupling lines are arranged on the fifth layer, and the folded coupling lines are arranged on the sixth layer; an input port with the impedance of 50 ohms is connected with one end of a first section of folding coupling line and one end of a first section of grounding folding coupling line, the other end of the first section of folding coupling line is open-circuited, the other end of the first section of grounding folding coupling line is connected with a front side grounding end, one end of a second section of folding coupling line is open-circuited, the other end of the second section of folding coupling line is connected with one end of a third section of folding coupling line, the other end of the third section of folding coupling line is open-circuited, one end of a fourth section of folding coupling line is open-circuited, the other end of the fourth section of folding coupling line is connected with one end of a fifth section of folding coupling line, the other end of the fifth section of folding coupling line is open-circuited, one end of a sixth section of folding coupling line is open-circuited, the other end of the sixth section of folding coupling line is connected with an, the left defected ground structure and the center defected ground structure and the right defected ground structure are located on the bottom ground layer.

Compared with the prior art, the invention has the following remarkable advantages: the invention realizes three-dimensional integration by adopting a low temperature co-fired ceramic (LTCC) process technology, has the advantages of ultra wide band, extremely low loss, compact structure, small volume, good electrical property, high integration, high yield, low expansion coefficient and the like, and can be widely used in the fields of military radar systems, satellite communication systems, medical treatment and the like with higher requirements on working stability.

Drawings

Fig. 1 is a schematic structural diagram of a double-ended open-coupled line-loaded stub ultra-wideband filter based on LTCC.

Fig. 2 is a top view of an LTCC-based double-ended open-coupled line-loaded stub ultra-wideband filter of the present invention.

Fig. 3 is a main performance curve diagram of the double-end open-circuit coupled line loading stub ultra-wideband filter based on LTCC.

Detailed Description

With reference to fig. 1 and fig. 2, an LTCC-based double-ended open-coupled line-loaded stub ultra-wideband filter includes an INPUT port INPUT and an OUTPUT port OUTPUT having a characteristic impedance of 50 ohms, a first folded coupling line L1, a second folded coupling line L2, a third folded coupling line L3, a fourth folded coupling line L4, a fifth folded coupling line L5, a sixth folded coupling line L6, a first folded coupling line L7, a second folded coupling line L8, a back ground terminal GND1, a front ground terminal GND2, a bottom ground layer GND3, a left defected ground structure DGS1, a center defected ground structure DGS2, and a right defected ground structure DGS 3.

The first section of folded coupling line L1 and the sixth section of folded coupling line L6 have the same structure, the second section of folded coupling line L2 and the fifth section of folded coupling line L5 have the same structure, the third section of folded coupling line L3 and the fourth section of folded coupling line L4 have the same structure, the first section of ground folded coupling line L7 and the second section of ground folded coupling line L8 have the same structure, and the left side defected ground structure DGS1 and the right side defected ground structure DGS3 have the same structure. Six sections of folding coupled lines and two sections of ground folding coupled lines count from top to bottom, the first section of folding coupled line L1 and the first section of ground folding coupled line L7 are located on the first layer, the second section of folding coupled line L2 and the third section of folding coupled line L3 are located on the second layer, the fourth section of folding coupled line L4 and the fifth section of folding coupled line L5 are located on the third layer, and the sixth section of folding coupled line L6 and the second section of ground folding coupled line L8 are located on the fourth layer. An INPUT port INPUT with an impedance of 50 ohms is connected to one end of a first folded coupling line L1 and one end of a first ground folded coupling line L7, the other end of the first folded coupling line L1 is open, the other end of the first ground folded coupling line L7 is connected to a front side ground terminal GND2, one end of a second folded coupling line L2 is open, the other end is connected to one end of a third folded coupling line L3, the other end of the third folded coupling line L3 is open, one end of a fourth folded coupling line L4 is open, the other end is connected to one end of a fifth folded coupling line L5, the other end of the fifth folded coupling line L5 is open, one end of a sixth folded coupling line L6 is open, the other end is connected to an OUTPUT port OUTPUT with an impedance of 50 ohms and one end of the second ground folded coupling line L8, the other end of the second ground folded coupling line L8 is connected to a front side ground terminal 2, a rear ground terminal 1 is connected to a front side ground terminal 2 and a bottom side ground terminal GND3, left and center defected ground structures DGS1 and DGS2 and right defected ground structure DGS3 are located on bottom ground layer GND 3.

The INPUT port INPUT, the OUTPUT port OUTPUT, the first section of folded coupling line L1, the second section of folded coupling line L2, the third section of folded coupling line L3, the fourth section of folded coupling line L4, the fifth section of folded coupling line L5, the sixth section of folded coupling line L6, the first section of folded coupling line L7, the second section of folded coupling line L8, the back side grounding end GND1, the front side grounding end GND2, the bottom grounding layer GND3, the left side defected ground structure DGS1, the center defected ground structure DGS2 and the right side defected ground structure DGS3 are all realized by a low-temperature co-fired ceramic LTCC process technology.

The first section of folding coupling line L1, the second section of folding coupling line L2, the third section of folding coupling line L3, the fourth section of folding coupling line L4, the fifth section of folding coupling line L5, the sixth section of folding coupling line L6, the first section of grounding folding coupling line L7 and the second section of grounding folding coupling line L8 are all folded to reduce the area, and the miniaturization of the filter is realized.

The first section of folding coupling line L1, the second section of folding coupling line L2, the third section of folding coupling line L3, the fourth section of folding coupling line L4, the fifth section of folding coupling line L5 and the sixth section of folding coupling line L6 are both double-end open-circuit coupling lines, the band-pass filtering characteristic of the ultra-wideband is achieved by adopting a wide-edge strong coupling structure, and meanwhile, the in-band performance and the steep side band are improved. The first section of the folded coupling line L7 and the second section of the folded coupling line L8 are quarter-wavelength short stub lines, and are equivalent to an RLC parallel broadband resonant unit. Better stop band rejection and squareness factor are achieved by loading the first segment of folded coupled ground line L7 and the second segment of folded coupled ground line L8 with double-ended open coupled lines. Left defected ground structure DGS1, center defected ground structure DGS2, and right defected ground structure DGS3 are all implemented by etching at bottom ground plane GND 3. The left side defected ground structure DGS1, the center defected ground structure DGS2, and the right side defected ground structure DGS3 are all dumbbell-shaped defected ground structures, and the high-end stop band attenuation is enhanced by generating a notch at the high end.

The invention realizes three-dimensional integration by the low-temperature co-fired ceramic LTCC process technology, thereby having the advantages of high stability, strong packaging density, high production yield, low production cost, strong severe environment resistance and the like.

In this embodiment, the size of the LTCC-based double-ended open-circuit coupled line loaded stub ultra-wideband filter is only 3.5mm × 1.9mm × 1.2mm, the operating frequency is 4 GHz-10.6 GHz, and as can be seen from fig. 3, the return loss of the ultra-wideband filter is better than 13 dB.

Claims

1. The utility model provides a bi-polar open circuit coupling line loading stub ultra wide band filter based on LTCC which characterized in that: the circuit comprises an INPUT port (INPUT), an OUTPUT port (OUTPUT), a first section of folding coupling line (L1), a second section of folding coupling line (L2), a third section of folding coupling line (L3), a fourth section of folding coupling line (L4), a fifth section of folding coupling line (L5), a sixth section of folding coupling line (L6), a first section of grounding folding coupling line (L7), a second section of grounding folding coupling line (L8), a rear side grounding end (GND1), a front side grounding end (GND2), a bottom grounding layer (GND3), a left side defect ground structure (DGS1), a center defect ground structure (DGS2) and a right side defect ground structure (DGS 3); the INPUT port (INPUT) and OUTPUT port (OUTPUT) characteristic impedances are both 50 ohms;

the first section of folding coupling line (L1) and the sixth section of folding coupling line (L6) have the same structure, the second section of folding coupling line (L2) and the fifth section of folding coupling line (L5) have the same structure, the third section of folding coupling line (L3) and the fourth section of folding coupling line (L4) have the same structure, the first section of grounding folding coupling line (L7) and the second section of grounding folding coupling line (L8) have the same structure, and the left side defected ground structure (DGS1) and the right side defected ground structure (DGS3) have the same structure; the folded coupling lines (L1) and the folded coupling lines (L7) are located on the first layer, the folded coupling lines (L2) and the folded coupling lines (L3) are located on the second layer, the folded coupling lines (L4) and the folded coupling lines (L5) are located on the third layer, and the folded coupling lines (L6) and the folded coupling lines (L8) are located on the fourth layer; an INPUT port (INPUT) with the impedance of 50 ohms is connected with one end of a first section of folding coupling line (L1) and one end of a first section of grounding folding coupling line (L7), the other end of the first section of folding coupling line (L1) is open-circuit, the other end of the first section of grounding folding coupling line (L7) is connected with a front side grounding end (GND2), one end of a second section of folding coupling line (L2) is open-circuit, the other end of the second section of folding coupling line is connected with one end of a third section of folding coupling line (L3), the other end of the third section of folding coupling line (L3) is open-circuit, one end of a fourth section of folding coupling line (L4) is open-circuit, the other end of the fourth section of folding coupling line (L6386525) is connected with one end of a fifth section of folding coupling line (L63 5), the other end of a sixth section of folding coupling line (L6) is open-circuit, the other end of the sixth section of folding coupling line is connected, the other end of the second segment of folded coupling line (L8) is connected to the front side ground terminal (GND2), the rear side ground terminal (GND1) is connected to the front side ground terminal (GND2) and the bottom ground layer (GND3), and the left side defective ground structure (DGS1), the center defective ground structure (DGS2) and the right side defective ground structure (DGS3) are located on the bottom ground layer (GND 3).

2. The LTCC-based double-ended open-coupled line-loaded stub ultra-wideband filter of claim 1, wherein: the low-temperature co-fired ceramic (LTCC) circuit comprises an INPUT port (INPUT), an OUTPUT port (OUTPUT), a first section of folding coupling line (L1), a second section of folding coupling line (L2), a third section of folding coupling line (L3), a fourth section of folding coupling line (L4), a fifth section of folding coupling line (L5), a sixth section of folding coupling line (L6), a first section of folding coupling line (L7), a second section of folding coupling line (L8), a rear side grounding end (GND1), a front side grounding end (GND2), a bottom grounding layer (GND3), a left side defected ground structure (DGS1), a center defected ground structure (DGS2) and a right side defected ground structure (DGS 3).

3. The LTCC-based double ended open coupled line loaded stub ultra wide band filter according to claim 1 or 2, wherein: the first section of folded coupling line (L1), the second section of folded coupling line (L2), the third section of folded coupling line (L3), the fourth section of folded coupling line (L4), the fifth section of folded coupling line (L5) and the sixth section of folded coupling line (L6) are both double-end open-circuit coupling lines.

4. The LTCC-based double ended open coupled line loaded stub ultra wide band filter according to claim 1 or 2, wherein: the first section of ground folded coupling line (L7) and the second section of ground folded coupling line (L8) are quarter-wavelength short stub lines, and are equivalent to RLC parallel broadband resonant units.

5. The LTCC-based double ended open coupled line loaded stub ultra wide band filter according to claim 1 or 2, wherein: the left defected ground structure (DGS1), the center defected ground structure (DGS2) and the right defected ground structure (DGS3) are all realized by etching at the bottom ground layer (GND 3); the left defected ground structure (DGS1), the center defected ground structure (DGS2) and the right defected ground structure (DGS3) are all dumbbell-shaped defected ground structures.