Improved layered one-to-two power divider based on LTCC

Abstract

The invention discloses an improved layered one-to-two power divider based on LTCC (Low Temperature Co-Fired Ceramic). The invention aims to meet the development requirements of modern wireless communication and ensure the communication quality of an ultra-wideband system as much as possible. According to the technical scheme, on the basis of a traditional multi-mode resonator, a stepped impedance resonator and a radial load are loaded, and an asymmetric coupling structure is used for introducing trapped waves. The band-pass filter has the advantages of wide stop band, strong out-of-band rejection capability, multiple trapped waves, high frequency selectivity and the like, is simple in structure, is convenient to connect with an active device, is low in manufacturing cost, and is suitable for batch production.

Description

Technical Field

[0001] The invention belongs to the technical field of microwave passive devices, and in particular relates to an improved layered one-to-two power divider based on LTCC. Background Art

[0002] With the rapid development of wireless communication technology, spectrum resources are becoming increasingly scarce. In order to meet the development needs of modern wireless communication, the requirements for filter performance are also increasing. In 2002, after the Federal Communications Commission authorized the 3.1GHz-10.6GHz frequency band for commercial use, ultra-wideband technology has ushered in rapid development and has been widely used in many fields, such as short-distance high-speed mobile communications, confidential communications, ground penetrating radar, etc. Since the working frequency band of the ultra-wideband filter is relatively wide, there are other wireless narrowband communication systems in this frequency band, such as WLAN (5.15-5.35GHz), WiMAX (3.4-3.6GHz), X-band satellite communication system (7.25-7.75GHz) and C-band communication satellite (5.925-6.425GHz). When these communication systems coexist with the ultra-wideband communication system, they will cause great interference to the communication quality of the ultra-wideband system. Therefore, it is necessary to introduce notches within the passband range of the ultra-wideband filter to eliminate these interferences; at the same time, in order to ensure the normal operation of the transmitting and receiving channels, it is necessary to meet the isolation requirements within the communication system and suppress the frequency points that generate intermodulation interference. Another requirement for the filter is strong out-of-band suppression capability. According to the above analysis, it can be seen that the current requirements for ultra-wideband filters are: multiple notches, wide stopband and high frequency selectivity. Summary of the invention

[0003] In order to better meet the development needs of modern wireless communications and maximize the communication quality of ultra-wideband systems, the present invention designs a wide-stopband ultra-wideband filter with multiple notches. The present invention has the advantages of wide stopband, strong out-of-band suppression capability, multiple notches, high rectangular coefficient, etc., and has a simple structure, low cost, and is easy to connect with active devices.

[0004] In order to solve the above problems and be applicable to real-life scenarios, the present invention is implemented through the following technical solutions: wide-stopband multi-notch ultra-wideband filter design, the key of which is to load a ladder impedance resonator and a radial load on the basis of a traditional multi-mode resonator. The ladder impedance resonator is symmetrically distributed on both sides of the low-impedance transmission line of the traditional multi-mode resonator, and the radial load is located above the low-impedance transmission line of the traditional multi-mode resonator; the input and output ports are cross-coupled with the multi-mode resonator, and the characteristic impedance of the input and output ports is 50 ohms. The introduction of notches is achieved by loading high-impedance transmission lines, coupling short-circuit stubs, and asymmetric coupling structures. In addition, the insertion loss and frequency selectivity at the cutoff frequency are improved by connecting a fan-shaped ladder impedance resonator in parallel. Then, the frequency selectivity and out-of-band suppression capability of the ultra-wideband filter are improved by coupling the transmission line structure and the defect ground structure, respectively.

[0005] Furthermore, the impedance of the 50 ohm input matching port (P1) is connected to a quarter-wavelength input feeder (L1), a single input feeder (L1) is connected to an asymmetric coupling structure (L2), and then the input feeder (L1) is cross-coupled with a high-impedance transmission line (L3) of the multi-mode resonator, the high-impedance transmission line (L3) of the multi-mode resonator is connected to a low-impedance transmission line (L4) of the multi-mode resonator, and then the right side of the multi-mode resonator is symmetrically connected, and is directly connected to the high-impedance transmission line (L3), cross-coupled with the output feeder, and the output feeder is directly connected to the output port (P2) and the asymmetric coupling structure. Then, the radial load (R1) and the stepped impedance structure (L7) are respectively connected to the upper middle position of the multimode resonator low impedance transmission line (L4) and the connection between the low impedance transmission line (L3) and the high impedance transmission line (L4), and connected to the open branch (L9) using a ring resonator (Rs), and then coupled with the radial load (R1), and then the open transmission line (L8) is connected to the radial load (R2), and then connected in parallel with the input matching port (P1) and the output matching port (P2), respectively. The short-circuit resonator (L6) is L-shaped coupled to the lower side of the multi-mode resonator low-impedance transmission line (L4) and is symmetrically distributed; the open-circuit transmission line (L5) is directly connected to the multi-mode resonator low-impedance transmission line (L4) and is located in the middle position below the multi-mode resonator low-impedance transmission line (L4); the C-type resonator (L10) is coupled with the input and output matching ports (P1, P2) and is located below it; the defective ground shape etched in the grounding metal plate is composed of a wider vertical transmission line (Ws2) and a narrower horizontal transmission line (Ls1) and the vertical transmission lines (Ws1) at both ends of the horizontal transmission line, and is coupled up and down with the multi-mode resonator low-impedance transmission line (L4).

[0006] Furthermore, input and output matching ports (P1, P2) with an impedance of 50 ohms, quarter-wavelength input and output feed lines (L1), an asymmetric coupling structure (L2), a multimode resonator high impedance transmission line (L3), a multimode resonator low impedance transmission line (L4), a radial load (R1), a stepped impedance resonator (L7), a ring-shaped resonator (Rs), an open transmission line (L9), an open transmission line (L8), a radial load (R2), a C-type resonator (L10), a short-circuit resonator (L6), and an open transmission line (L5) are all realized by using a microstrip process.

[0007] The wider vertical transmission line (Ws2), the narrower vertical transmission line (Ws1) and the horizontal transmission line (Ls1) on the grounding metal plate are all defective structures, that is, such shapes are etched on the grounding metal plate.

[0008] The beneficial effects of the present invention are: The present invention designs an improved wide stopband multi-notch ultra-wideband filter based on a traditional multi-mode resonator, and utilizes its process characteristics to realize a planar notch type ultra-wideband filter. The wide stopband and multiple notches are realized by improving the shape of the multi-mode resonator and adding a defective structure. This design reduces the overall size and improves the overall performance, and has the advantages of simple structure, easy connection with active devices, and mass production. In addition, the number of notches is large, the frequency selectivity is good, the insertion loss is small, and the stopband width and out-of-band suppression capability are greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to more clearly demonstrate the technical solution of the present invention, the following is a brief introduction to the drawings used in this design. Obviously, the following are some brief embodiments of the present invention, and for researchers conducting research in this field, other valuable drawings can also be obtained according to the embodiments of the present invention.

[0010] Figure 1 It is a schematic diagram of the overall structure of the microstrip of the present invention; Figure 2 is a schematic diagram of a defective ground structure of the present invention; Figure 3 is an S parameter curve diagram of the present invention; DETAILED DESCRIPTION

[0011] The following will fully describe the technical solutions and designs in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. The embodiments introduced this time are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0012] The invention discloses an improved ultra-wideband filter based on a multimode resonator, which is mainly divided into two parts, namely, a multimode resonator main body part and a performance improvement part. The main body part includes a multimode resonator and a radial load and a step impedance resonator loaded on the multimode resonator. The performance improvement part includes a high-impedance transmission line loaded on the multimode resonator, a short-circuit transmission line coupled with the multimode resonator, an asymmetric coupling structure loaded at the input and output feeder, a fan-shaped step impedance resonator connected in parallel with the input and output ports, a C-type transmission line coupled with the input and output ports, a transmission line coupled with the multimode resonator, and a defective ground structure under the dielectric substrate. The present invention can realize a wide stopband ultra-wideband filter by using an improved multi-mode resonator, and introduce three notches by loading a high impedance resonator structure, an asymmetric coupling structure, and a coupled short-circuit transmission line structure; at the same time, a fan-shaped step impedance resonator is connected in parallel at the input and output ports to improve the insertion loss and frequency selectivity at the lower cutoff frequency; finally, the out-of-band suppression characteristics of the ultra-wideband filter are improved by loading a defective ground structure below the multi-mode resonator, and a transmission line structure is coupled above the radial load of the multi-mode resonator at the input and output ports to generate two transmission zeros at the upper cutoff frequency of the ultra-wideband filter to improve the frequency selectivity. The structure is simple in design, low in cost, and suitable for today's communication systems. Example

[0013] Combination Figure 1 , Figure 2 An ultra-wideband filter designed based on a traditional multi-mode resonator is improved by loading a stepped impedance resonator and a radial load on the traditional multi-mode resonator, and improving the single-line coupling of the traditional multi-mode resonator into a double-line cross-toe coupling.

[0014] Combination Figure 1 , Figure 2 An improved ultra-wideband filter based on traditional multi-mode resonators introduces three notches by introducing asymmetric coupling structures in the input and output feed lines, loading high-impedance transmission lines, and coupling short-circuit resonators to shield the influence of other wireless narrowband communication systems on the ultra-wideband communication system; and by connecting fan-shaped stepped impedance resonators in parallel at the input and output matching ports to improve frequency selectivity and reduce insertion loss; and then introduces coupling structures and defective ground structures to improve rectangular coefficients and out-of-band suppression capabilities.

[0015] Combination Figure 1 , Figure 2, an improved ultra-wideband filter based on a traditional multi-mode resonator, comprising an input matching port P1 with an impedance of 50 ohms, an output matching port P2 with an impedance of 50 ohms, an input-output feeder line L1 forming a three-line cross-coupling with the input-output matching port, an asymmetric coupling structure L2 introducing a notch, a high-impedance transmission line L3 of the multi-mode resonator, a low-impedance transmission line L4 of the multi-mode resonator, a high-impedance transmission line L5 introducing a notch, a short-circuit resonator L6 introducing a notch, a stepped impedance resonator L7 loaded on the traditional multi-mode resonator, an open-circuit transmission line L8 connected in parallel with the input-output matching port, an open-circuit transmission line L9 connected to a ring-shaped resonator Rs, a C-type resonator L10 coupled to the input-output matching port, a radial load R1 loaded above the low-impedance transmission line of the traditional multi-mode resonator, and a radial load R2 connected to the open-circuit transmission line connected in parallel with the input-output matching port.

[0016] Combination Figure 1 , Figure 2 The impedance of the input matching port P1 is 50 ohms and connected to the quarter-wavelength input feeder L1. A single line of the input feeder L1 is connected to the asymmetric coupling structure L2. Then the input feeder L1 is cross-coupled with the high impedance transmission line L3 of the multi-mode resonator. The high impedance transmission line L3 of the multi-mode resonator is connected to the low impedance transmission line L4 of the multi-mode resonator. Then the right side of the multi-mode resonator is symmetrically connected, and is directly connected to the high impedance transmission line L3 and cross-coupled with the output feeder. The output feeder is directly connected to the output port P2 and the asymmetric coupling structure respectively. Then, the radial load R1 and the stepped impedance structure L7 are respectively connected to the upper and middle position of the multi-mode resonator low-impedance transmission line L4 and the connection between the low-impedance transmission line L3 and the high-impedance transmission line L4, and connected to the open branch L9 using the ring resonator Rs. After the connection, they are coupled with the radial load R1. Then, the open transmission line L8 is connected to the radial load R2, and after the connection, they are respectively connected in parallel with the input matching port P1 and the output matching port P2. The short-circuit resonator L6 is L-shaped coupled to the lower side of the multi-mode resonator low-impedance transmission line L4 and is symmetrically distributed; the open-circuit transmission line L5 is directly connected to the multi-mode resonator low-impedance transmission line L4 and is located in the middle position below the multi-mode resonator low-impedance transmission line L4. The C-type resonator L10 is coupled with the input and output matching ports P1 and P2 and is located below it; the defective ground shape etched in the grounding metal plate is composed of a wider vertical transmission line Ws2, a narrower horizontal transmission line Ls1, and vertical transmission lines Ws1 at both ends of the horizontal transmission line, and is coupled up and down with the multi-mode resonator low-impedance transmission line L4.

[0017] The input and output matching ports P1 and P2 with an impedance of 50 ohms, the quarter-wavelength input and output feeder L1, the asymmetric coupling structure L2, the multimode resonator high-impedance transmission line L3, the multimode resonator low-impedance transmission line L4, the radial load R1, the stepped impedance resonator L7, the ring-type resonator Rs, the open transmission line L9, the open transmission line L8, the radial load R2, the C-type resonator L10, the short-circuit resonator L6, and the open transmission line L5 are all realized by using microstrip technology.

[0018] The wider vertical transmission line Ws2, the narrower vertical transmission line Ws1 and the horizontal transmission line Ls1 on the ground metal plate are all defective structures, that is, such shapes are etched on the ground metal plate. Example

[0019] The present invention discloses an improved wide stopband multi-notch ultra-wideband filter based on a traditional multi-mode resonator, which is realized based on microstrip process technology, with a dielectric relative dielectric constant of 2.5, a dielectric substrate thickness of 0.794 mm, and a loss tangent of 0.0009. An ultra-wideband filter with good performance and a wide stopband is obtained by improving the traditional multi-mode resonator, and three notches are introduced by loading three different structures to shield interference from other wireless narrowband communication systems; and its performance is further improved by loading a coupling structure, a parallel fan-shaped ladder impedance resonator structure, and a defective ground structure.

[0020] The improved ultra-wideband filter based on the conventional multi-mode resonator of the present invention has the following performance: Figure 3 It can be seen that the passband range is 4.1GHz-10.6GHz, the relative bandwidth is 93.4%; the insertion loss is less than 1.3dB, the passband is relatively flat, and the ripple is small; and the frequency selectivity factor is 0.81, and the frequency selectivity at the upper and lower cutoff frequencies is good; the three notch points are located at 5.1GHz, 6.28GHz and 8.1GHz, respectively, the notch bandwidths are 4.5GHz-5.3GHz, 5.8GHz-6.4GHz, 7.7GHz-8.2GHz, and the notch depths are 25dB, 35dB, and 42dB, respectively; the stopband range reaches 25GHz, and the out-of-band suppression reaches -24.5dB. It can be seen that the filter can effectively shield the interference of WLAN signals, Indian national communication satellite C-band and X-band communication satellites, and ensure the communication quality of ultra-wideband systems.

[0021] It should be understood that the detailed description of the technical solutions of the present invention by means of the preferred embodiments is illustrative rather than restrictive. A person skilled in the art may modify the technical solutions described in the embodiments, or replace some of the technical features by equivalents, based on reading the specification of the present invention; and these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An improved layered one-to-two power divider based on LTCC, based on a traditional multi-mode resonator, characterized by: The power divider is loaded with a stepped impedance resonator and a radial load on a conventional multi-mode resonator, and three notches are introduced by loading a high impedance transmission line, an asymmetric coupling structure, and a coupled short-circuit stub; Connecting fan-shaped stepped impedance resonators in parallel at the input and output matching ports improves insertion loss and frequency selectivity; The C-type resonator and the ring-shaped resonator are coupled to the input and output matching ports and the upper end of the radial load respectively, wherein the C-type resonator is symmetrically distributed on the left and right sides; An irregular cross-shaped defect ground structure is introduced into the ground substrate below the multi-mode resonator.

2. The improved layered one-to-two power divider based on LTCC according to claim 1, comprising a conventional multi-mode resonator, characterized in that: The characteristic impedance of the input matching port and the output matching port are both 50 ohms.

3. The improved layered one-to-two power divider based on LTCC according to claim 2, comprising a conventional multi-mode resonator, characterized in that: The impedance of the 50 ohm input matching port (P1) is connected to a quarter-wavelength input feeder (L1), and a single input feeder (L1) is connected to an asymmetric coupling structure (L2); Then the input feed line (L1) is cross-coupled with the high impedance transmission line (L3) of the multi-mode resonator, and the high impedance transmission line (L3) of the multi-mode resonator is connected with the low impedance transmission line (L4) of the multi-mode resonator; Then, the right side of the multi-mode resonator is symmetrically connected, directly connected to the high impedance transmission line (L3), and cross-coupled with the output feeder, and the output feeder is directly connected to the output port (P2) and the asymmetrical coupling structure; Then, the radial load (R1) and the step impedance structure (L7) are connected to the upper middle position of the multi-mode resonator low impedance transmission line (L4) and the connection between the low impedance transmission line (L3) and the high impedance transmission line (L4), and connected to the open branch (L9) using the ring resonator (Rs); After the connection, it is coupled with the radial load (R1), and then the open transmission line (L8) is connected to the radial load (R2), and after the connection, it is connected in parallel with the input matching port (P1) and the output matching port (P2).

4. The improved layered one-to-two power divider based on LTCC according to claim 3, comprising a conventional multi-mode resonator, characterized in that: The short-circuit resonator (L6) is L-shaped coupled to the lower side of the multi-mode resonator low impedance transmission line (L4) and is symmetrically distributed; The open transmission line (L5) is directly connected to the multi-mode resonator low impedance transmission line (L4) and is located in the middle below the multi-mode resonator low impedance transmission line (L4). The C-type resonator (L10) is coupled to the input and output matching ports (P1, P2) and is located below the C-type resonator (L10). The defective ground shape etched in the ground metal plate consists of a wider vertical transmission line (Ws2) and a narrower horizontal transmission line (Ls1) as well as the vertical transmission lines (Ws1) at both ends of the horizontal transmission line, and is coupled up and down with the multi-mode resonator low-impedance transmission line (L4).

5. The improved layered one-to-two power divider based on LTCC according to claim 2, comprising a conventional multi-mode resonator, characterized in that: The input and output matching ports with an impedance of 50 ohms (P1, P2), quarter-wavelength input and output feed lines (L1), asymmetric coupling structure (L2), multimode resonator high impedance transmission line (L3), multimode resonator low impedance transmission line (L4), radial load (R1), stepped impedance resonator (L7), ring resonator (Rs), open transmission line (L9), open transmission line (L8), radial load (R2), C-type resonator (L10), short-circuit resonator (L6), and open transmission line (L5) are all realized by using microstrip technology.

6. The improved layered one-to-two power divider based on LTCC according to claim 5, comprising a conventional multi-mode resonator, characterized in that: The wider vertical transmission line (Ws2), the narrower vertical transmission line (Ws1) and the horizontal transmission line (Ls1) on the grounding metal plate are all defective structures, that is, such shapes are etched on the grounding metal plate.

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