Multi-mode bandpass filter structure and k-band filter based on IPD

Abstract

The present invention proposes a multi-mode bandpass filter structure and a k-band filter based on IPD, which belongs to the field of satellite communication. The filter proposed by the present invention has both notch and cross-coupling modes based on the IPD process, including: a substrate, a metal routing layer and a resonator layer deployed on one surface of the substrate, the resonator layer is located next to the 50Ω transmission line of the substrate, and is connected to the back metal through a metal through hole; wherein the resonator layer is composed of a half-wavelength "mountain"-shaped short-circuit branch loaded resonator Q0 and a 4th-order open ring cross-coupling resonator. Compared with traditional bandpass filters, the technical solution of the present invention can effectively improve the far-end suppression of the K-band bandpass filter.

Description

Technical Field

[0001] The present invention relates to the field of satellite communication, and in particular to a multi-mode bandpass filter structure and a K-band filter based on IPD. Background Art

[0002] With the development of communication technology and chip technology, K-band bandpass filters are widely used in many fields, especially in wireless communication systems. They are common passive components in the fields of integrated circuits and microwaves. The basic principle of K-band bandpass filters is composed of cross-coupling of resonant units. By introducing additional cross-coupling between non-adjacent resonant units, the stopband produces a finite frequency attenuation pole without increasing the order, which can improve the steepness between the passband and the stopband to improve the performance of the filter. It has the characteristics of an approximate elliptic function.

[0003] The Ku-band cross-coupled bandpass filter proposed in the prior art patent CN202410599226.1 mainly replaces the quarter-wavelength microstrip line in the middle of the fifth-order comb line filter with a half-wavelength U-shaped microstrip line, which improves the rectangular coefficient of the low-frequency band, but the rectangular coefficient of the high-frequency part and the high-frequency far-end suppression are still relatively poor, and the far-end suppression can only reach 25G, and the suppression is more obvious at farther distances. Summary of the invention

[0004] In order to overcome the above defects in the prior art, the present invention proposes a multi-mode bandpass filter structure and a k-band filter based on IPD, which can simultaneously improve the high and low end rectangular coefficients of the bandpass filter and achieve up to 40G far-end suppression.

[0005] In order to achieve the object of the present invention, the technical solution of the present invention is as follows:

[0006] In a first aspect, the present invention provides a multi-mode bandpass filter structure based on IPD, wherein the bandpass filter structure has both notch and cross-coupling modes based on the IPD process, and comprises: a substrate, a metal routing layer and a resonator layer disposed on one surface of the substrate, wherein the resonator layer is located at 50° of the substrate. Next to the transmission line, it is connected to the back metal through a metal through hole;

[0007] The resonator layer is composed of a half-wavelength "mountain"-shaped short-circuit branch-loaded resonator Q0 and a 4th-order open-ring cross-coupled resonator.

[0008] Furthermore, the 4th-order open-ring cross-coupled resonator includes a first open-ring resonator Q1, a second open-ring resonator Q2, a third open-ring resonator Q3 and a fourth open-ring resonator Q4, each of which has a microstrip line of one quarter wavelength; wherein the first open-ring resonator Q1 and the fourth open-ring resonator Q4 are in a mirror-symmetrical structure, the second open-ring resonator Q2 and the third open-ring resonator Q3 are in a mirror-symmetrical structure, the first open-ring resonator Q1 and the second open-ring resonator Q2 are parallel, the fourth open-ring resonator Q4 and the third open-ring resonator Q3 are parallel, and the 4th-order open-ring cross-coupled resonator has an overall field-shaped structure.

[0009] Furthermore, the base adopts a GaAs substrate with a relative dielectric constant of 12.9 and a thickness of 100 μm.

[0010] Furthermore, the center frequency of the short-circuit branch-loaded resonator Q0 is 24 GHz, the length is 500 um, and the width is 290 um.

[0011] Furthermore, the center frequency of the four resonators in the 4th-order open-ring cross-coupled resonator is 24 GHz, and the length and width are both 670 um.

[0012] Furthermore, the 50 The transmission line includes an input port and an output port, wherein the input port is connected to the output port through the short-circuit stub loading resonator Q0, the first open ring resonator Q1, and the fourth open ring resonator Q4 which are connected in sequence.

[0013] Furthermore, when the short-circuited branch-loaded resonator Q0 is excited in odd mode, the odd-mode input impedance from the input end is:

[0014] ;

[0015] When the short-circuited branch-loaded resonator Q0 is excited in even mode, the even-mode input impedance from the input end is:

[0016] ;

[0017] In the above formula, the impedances of the two transmission lines of the short-circuited branch loaded with the resonator Q0 are Z1 and Z2, respectively, the electrical lengths of the two transmission lines of the short-circuited branch loaded with the resonator Q0 are θ1 and θ2, respectively, and j is an imaginary unit.

[0018] Furthermore, the resonant frequency of the short-circuited branch loaded resonator Q0 is:

[0019] ;

[0020] In the formula, c represents the speed of light in vacuum, represents the effective dielectric constant of the dielectric substrate, Indicates the width of the open branches at both ends, Indicates the total width of the open branch. Indicates the total length of the intermediate open branches.

[0021] Furthermore, the middle part of the short-circuit branch-loaded resonator Q0 is a short-circuit branch, which is equivalent to a grounding capacitor; and the two end parts are open-circuit branches, which are equivalent to inductors.

[0022] In a second aspect, the present invention further proposes a K-band filter, the K-band filter comprising:

[0023] Based on 50 Input ports and output ports of transmission lines;

[0024] A "mountain"-shaped short-circuit branch loading resonator Q0 located next to the input port; and a 4th-order open-ring cross-coupled resonator;

[0025] The 4th-order open-ring cross-coupled resonator includes a first open-ring resonator Q1, a second open-ring resonator Q2, a third open-ring resonator Q3 and a fourth open-ring resonator Q4, each of which has a microstrip line of a quarter wavelength; the first open-ring resonator Q1 and the fourth open-ring resonator Q4 are in a mirror-symmetrical structure, the second open-ring resonator Q2 and the third open-ring resonator Q3 are in a mirror-symmetrical structure, the first open-ring resonator Q1 is parallel to the second open-ring resonator Q2, the fourth open-ring resonator Q4 is parallel to the third open-ring resonator Q3, and the 4th-order open-ring cross-coupled resonator is in a field-shaped structure as a whole;

[0026] The input port is connected to the output port through the short-circuit branch loading resonator Q0, the first open ring resonator Q1, and the fourth open ring resonator Q4 connected in sequence;

[0027] The middle part of the short-circuit branch-loaded resonator Q0 is a short-circuit branch, which is equivalent to a grounded capacitor, and the two end parts are open-circuit branches, which are equivalent to inductors.

[0028] The technical solution provided by the present invention creatively proposes a K-band bandpass filter with both notch and cross coupling based on IPD technology, embedding the "mountain" shaped short-circuit branch loading resonator into 50 Next to the transmission line, the insertion loss and high and low end rectangular suppression of the K-band bandpass filter will not be affected. Compared with the traditional bandpass filter, its beneficial effect is that it can effectively improve the far-end suppression of the K-band bandpass filter.

[0029] From the structure of the ring, it can be seen that the open ring resonance can be more compact than the U-shaped microstrip line. The cross-coupling form is a new type of microstrip filter developed in recent years, which is composed of cross-coupling of resonant units. It introduces additional cross-coupling between non-adjacent resonant units. Without increasing the order, the stop band produces a finite frequency attenuation pole, which can increase the steepness between the passband and the stopband to improve the performance of the filter. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings are used to provide a further understanding of the technical solution of the present invention and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present invention and do not constitute a limitation on the technical solution of the present invention.

[0031] Figure 1 This is a structural diagram of a K-band bandpass filter with both notch and cross coupling based on IPD technology provided in an embodiment of the present invention.

[0032] Figure 2 A schematic diagram of the structure of a “mountain” type short-circuited branch resonator provided in an embodiment of the present invention.

[0033] Figure 3 A schematic diagram comparing simulation results of a bandpass filter with a novel notch structure provided in an embodiment of the present invention and simulation results of an original bandpass filter without a notch structure.

[0034] exist Figure 1 In the example, 1 means 50. Transmission line input port, 2 represents the short-circuit branch loading resonator Q0, 3 represents the first open ring resonator Q1, 4 represents the second open ring resonator Q2, 5 represents the third open ring resonator Q3, 6 represents the fourth open ring resonator Q4, 7 represents 50 Transmission line output port output port. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the present invention more clear, the embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other arbitrarily without conflict.

[0036] The terms "comprises" and "having" and any variations thereof in the description embodiments, claims and drawings of the present invention are intended to cover non-exclusive inclusions, for example, including a series of steps or units.

[0037] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0038] like Figure 1As shown, the present invention provides a multi-mode bandpass filter structure based on IPD, the bandpass filter structure has both notch and cross-coupling modes based on IPD technology, including: a substrate, a metal routing layer and a resonator layer disposed on one surface of the substrate, the resonator layer is located at 50 Next to the transmission line, it is connected to the back metal through a metal through hole; wherein the resonator layer is composed of a half-wavelength "mountain"-shaped short-circuit branch loaded resonator Q0 and a 4th-order open ring cross-coupled resonator.

[0039] In this embodiment, the multi-mode bandpass filter structure is made of a metal microstrip line on one side of the substrate, and a gold-clad ground plane on the other side, wherein the substrate is a GaAs substrate with a relative dielectric constant of 12.9 and a thickness of 100 μm, and the surface microstrip line and the back material are Au. The metal thickness is 3.5 μm and 4 μm respectively.

[0040] It should be noted that the "mountain"-shaped short-circuit branch-loaded resonator has a short-circuit branch in the middle with a metal through-hole connected to the back metal, which is equivalent to a grounding capacitor. The open-circuit branches at both ends are equivalent to inductors. The entire structure can be regarded as an LC resonant circuit.

[0041] In this embodiment, the 4th-order open-ring cross-coupled resonator includes a first open-ring resonator Q1, a second open-ring resonator Q2, a third open-ring resonator Q3 and a fourth open-ring resonator Q4, each of which has a microstrip line of one-quarter wavelength; wherein the first open-ring resonator Q1 and the fourth open-ring resonator Q4 are in a mirror-symmetrical structure, the second open-ring resonator Q2 and the third open-ring resonator Q3 are in a mirror-symmetrical structure, the first open-ring resonator Q1 and the second open-ring resonator Q2 are parallel, the fourth open-ring resonator Q4 and the third open-ring resonator Q3 are parallel, and the 4th-order open-ring cross-coupled resonator has a field-shaped structure as a whole.

[0042] It should be noted that 50 The transmission line includes an input port and an output port, wherein the input port is connected to the output port through a short-circuit stub-loaded resonator Q0 , a first open-ring resonator Q1 , and a fourth open-ring resonator Q4 that are connected in sequence.

[0043] In this embodiment, the total length of the resonator is as follows: for a K-band bandpass filter with a center frequency of 24 GHz, the length of a quarter-wavelength resonator is 670 um, while the length of a conventional quarter-wavelength resonator is 2680 um; the length of the resonator of the present invention is about 1 / 4 of the conventional resonator, the volume of the filter is reduced by about 3 / 4, and the physical size of the filter is 2650*2000*100 um. The center frequency of the short-circuit branch loading resonator Q0 is 24 GHz, the length is 500 um, and the width is 290 um.

[0044] In this embodiment, the first split ring resonator Q1 and 50 A "mountain"-shaped short-circuit branch loading resonator is added next to the input port of the transmission line to achieve high suppression of the 40G far end of the bandpass filter. Figure 2 As shown. Electric coupling is generated between the first split ring resonator and the second split ring resonator, magnetic coupling is generated between the second split ring resonator and the third split ring resonator, and mixed coupling is generated between the first split ring resonator and the third split ring resonator. Multiple coupling modes realize the generation of zero points of high and low end moments, so that the rectangular coefficient is significantly improved.

[0045] In this embodiment, the entire “mountain”-shaped resonator structure is symmetrical about the center line, and an odd-even mode analysis method is used to analyze its resonance characteristics.

[0046] When odd-mode excitation is used, the odd-mode input impedance seen from the input end is:

[0047] ;

[0048] When using even-mode excitation, the even-mode input impedance seen from the input end is

[0049] ;

[0050] The impedances of the two transmission lines of the short-circuited branch loaded resonator Q0 are Z1 and Z2, respectively, the electrical lengths of the two transmission lines of the short-circuited branch loaded resonator Q0 are θ1 and θ2, respectively, and j is an imaginary unit.

[0051] In this embodiment, the resonance condition of the short-circuited branch-loaded resonator Q0 is determined by the electrical lengths θ1 and θ2 of the two transmission lines and their admittance ratio k, where the electrical length 2 / 4 remains unchanged, which means that the odd-mode resonant frequency is a constant value. After calculation, it is found that its odd-mode resonant frequency cannot be used as a notch frequency outside the ultra-wideband passband. Therefore, only its even-mode resonant frequency can be used to achieve the notch characteristic. According to the condition 2Z1=Z2, it can be obtained that θ1+θ2=λg / 4 (λg is the waveguide wavelength corresponding to the even-mode resonant frequency), so the resonant frequency of the "mountain" type short-circuited branch resonator can be obtained as:

[0052] ;

[0053] In the formula, c represents the speed of light in vacuum, represents the effective dielectric constant of the dielectric substrate, such as Figure 2 As shown, Indicates the width of the open branches at both ends, Indicates the total width of the open branch. Indicates the total length of the intermediate open branches.

[0054] It can be seen from the formula that the resonant frequency of the "mountain" resonator is only related to , , The three parameters are related and inversely proportional.

[0055] In this embodiment, the "mountain" shaped short-circuit branch loading resonator can be reduced as the branch length increases, which can well realize the miniaturization of the resonator. By coupling the resonator with an ultra-wideband filter, the notch characteristics of the filter can be realized. And by changing the physical size of the "mountain" shaped resonator, the desired notch position can be conveniently and flexibly adjusted.

[0056] According to the purpose of the present invention, the present invention also proposes a K-band filter, the K-band filter comprising:

[0057] Based on 50 Input ports and output ports of transmission lines;

[0058] A "mountain"-shaped short-circuit branch loading resonator Q0 located next to the input port; and a 4th-order open-ring cross-coupled resonator;

[0059] The 4th-order open-ring cross-coupled resonator includes a first open-ring resonator Q1, a second open-ring resonator Q2, a third open-ring resonator Q3 and a fourth open-ring resonator Q4, each of which has a microstrip line of a quarter wavelength; the first open-ring resonator Q1 and the fourth open-ring resonator Q4 are in a mirror-symmetrical structure, the second open-ring resonator Q2 and the third open-ring resonator Q3 are in a mirror-symmetrical structure, the first open-ring resonator Q1 is parallel to the second open-ring resonator Q2, the fourth open-ring resonator Q4 is parallel to the third open-ring resonator Q3, and the 4th-order open-ring cross-coupled resonator is in a field-shaped structure as a whole;

[0060] The input port is connected to the output port through the short-circuit branch loading resonator Q0, the first open ring resonator Q1, and the fourth open ring resonator Q4 connected in sequence;

[0061] The middle part of the short-circuit branch-loaded resonator Q0 is a short-circuit branch, which is equivalent to a grounded capacitor, and the two end parts are open-circuit branches, which are equivalent to inductors.

[0062] Figure 3 The simulation results show that the center frequency of the filter is 24GHz, the bandwidth is 0.5GHz, the in-band insertion loss is less than 2.6dB, the return loss is greater than 18dB, the lower sideband transition section attenuates 35dB within the 2GHz bandwidth, and the upper sideband transition section attenuates 40dB within the 2GHz bandwidth. There is a transmission zero point in the upper and lower sidebands, which improves the high and low end rectangular coefficients.

[0063] according to Figure 3 It is shown that when the "mountain" shaped short-circuit branch loading resonator is introduced, the 40G far-end suppression is significantly improved. The 40G far-end suppression is increased from 34dB without the trap structure to 57dB with the "mountain" shaped trap structure, an increase of 23dB, and the effect is very obvious.

[0064] Based on the above performance analysis, it can be seen that the K-band bandpass filter with both notch and cross-coupling based on the IPD process provided by the embodiment of the present invention has the advantages of small size, deep notch point, high selectivity, good rectangular coefficient, and strong far-end suppression capability, which makes the present invention have stronger advantages than other similar products on the market and is conducive to large-scale production and application.

[0065] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and should be understood that the scope of protection of the present invention is not limited to such specific statements and embodiments. Any person skilled in the art in the field to which the present invention belongs can make any modifications and changes in the form and details of implementation without departing from the spirit and scope disclosed by the present invention, and these are all within the scope of protection of the present invention. Therefore, the scope of patent protection of the present invention shall still be subject to the scope defined by the attached claims.

Claims

1. A multi-mode bandpass filter structure based on IPD, characterized in that: The bandpass filter structure has both notch and cross-coupling modes based on the IPD process, and includes: a substrate, a metal wiring layer and a resonator layer disposed on one surface of the substrate, and the resonator Q0 layer is located at 50 Next to the transmission line, it is connected to the back metal through a metal through hole. The resonator Q1~Q4 layer is located at 50 Between the input port and the output port of the transmission line; The resonator layer is composed of a half-wavelength "mountain"-shaped short-circuit branch-loaded resonator Q0 and a 4th-order open-ring cross-coupled resonator; The 4th-order open-ring cross-coupled resonator includes a first open-ring resonator Q1, a second open-ring resonator Q2, a third open-ring resonator Q3 and a fourth open-ring resonator Q4, each of which has a microstrip line of a quarter wavelength; wherein the first open-ring resonator Q1 and the fourth open-ring resonator Q4 are in a mirror-symmetrical structure, the second open-ring resonator Q2 and the third open-ring resonator Q3 are in a mirror-symmetrical structure, the first open-ring resonator Q1 and the second open-ring resonator Q2 are parallel, the fourth open-ring resonator Q4 and the third open-ring resonator Q3 are parallel, and the 4th-order open-ring cross-coupled resonator is in a field-shaped structure as a whole; When the short-circuited branch-loaded resonator Q0 is excited in odd mode, the odd-mode input impedance from the input end is: ； When the short-circuited branch-loaded resonator Q0 is excited in even mode, the even-mode input impedance from the input end is: ； In the above formula, the impedances of the two transmission lines of the short-circuited branch loaded with the resonator Q0 are Z1 and Z2, respectively, the electrical lengths of the two transmission lines of the short-circuited branch loaded with the resonator Q0 are θ1 and θ2, respectively, and j is an imaginary unit.

2. The multi-mode bandpass filter structure based on IPD according to claim 1, characterized in that: The base is a GaAs substrate with a relative dielectric constant of 12.9 and a thickness of 100 μm.

3. The multi-mode bandpass filter structure based on IPD according to claim 1, characterized in that: The short-circuit branch-loaded resonator Q0 has a center frequency of 24 GHz, a length of 500 um, and a width of 290 um.

4. The IPD-based multi-mode bandpass filter structure according to claim 1, characterized in that: The center frequency of the four resonators in the 4th-order open-ring cross-coupled resonator is 24 GHz, and the length and width are both 670 um.

5. The multi-mode bandpass filter structure based on IPD according to claim 1, characterized in that: The 50 The transmission line includes an input port and an output port, wherein the input port is connected to the output port through the short-circuit stub loading resonator Q0, the first open-ring resonator Q1, and the fourth open-ring resonator Q4 connected in sequence.

6. The IPD-based multi-mode bandpass filter structure according to claim 1, characterized in that: The resonant frequency of the short-circuited branch loaded resonator Q0 is: ； In the formula, c is the speed of light in vacuum, ɛ e represents the effective dielectric constant of the dielectric substrate, w l1 Indicates the width of the open branches at both ends, S l1 Indicates the total width of the open branch. S l2 Indicates the total length of the intermediate open branches.

7. The IPD-based multi-mode bandpass filter structure according to claim 6, characterized in that: The middle part of the short-circuit branch-loaded resonator Q0 is a short-circuit branch, which is equivalent to a grounding capacitor; and the two end parts are open-circuit branches, which are equivalent to inductors.

8. A K-band filter, characterized in that: The K-band filter comprises: Based on 50 Input ports and output ports of transmission lines; A "mountain"-shaped short-circuit branch loading resonator Q0 located next to the input port; and a 4th-order open-ring cross-coupled resonator; The 4th-order open-ring cross-coupled resonator includes a first open-ring resonator Q1, a second open-ring resonator Q2, a third open-ring resonator Q3 and a fourth open-ring resonator Q4, each of which has a microstrip line of a quarter wavelength; the first open-ring resonator Q1 and the fourth open-ring resonator Q4 are in a mirror-symmetrical structure, the second open-ring resonator Q2 and the third open-ring resonator Q3 are in a mirror-symmetrical structure, the first open-ring resonator Q1 is parallel to the second open-ring resonator Q2, the fourth open-ring resonator Q4 is parallel to the third open-ring resonator Q3, and the 4th-order open-ring cross-coupled resonator is in a field-shaped structure as a whole; The input port is connected to the output port through the short-circuit branch loading resonator Q0, the first open ring resonator Q1, and the fourth open ring resonator Q4 connected in sequence; When the short-circuited branch-loaded resonator Q0 is excited in odd mode, the odd-mode input impedance from the input end is: ； When the short-circuited branch-loaded resonator Q0 is excited in even mode, the even-mode input impedance from the input end is: ； In the above formula, the impedances of the two transmission lines of the short-circuited branch loaded with the resonator Q0 are Z1 and Z2, respectively, the electrical lengths of the two transmission lines of the short-circuited branch loaded with the resonator Q0 are θ1 and θ2, respectively, and j is an imaginary unit; The middle part of the short-circuit branch-loaded resonator Q0 is a short-circuit branch, which is equivalent to a grounded capacitor, and the two end parts are open-circuit branches, which are equivalent to inductors.

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