A cross-coupled bandpass filter based on IPD technology

Abstract

The present invention provides a cross-coupled bandpass filter based on IPD technology, the filter comprising: a substrate, a metal wiring layer; metal electrodes and capacitors are made on one side of the substrate, and the other side is a gold-clad ground plate; a feeder, a first feeder port and a second feeder port are respectively arranged on the metal wiring layer; one end of the feeder is connected to a resonator, and the other end is connected to a GSG port for testing; the structure of the filter is that a quarter-wavelength microstrip line in the middle of a fifth-order combline filter is replaced by a half-wavelength U-shaped microstrip line.

Description

Technical Field

[0001] The present invention relates to a field, and in particular to a cross-coupled bandpass filter based on IPD technology. Background Art

[0002] With the rapid development of wireless communication, the division between channels is becoming more and more detailed. Microwave filters, which separate useful and useless signals, have become important components in communication systems, and the requirements for the rectangular coefficient of filters are getting higher and higher. Now, microwave filters have been widely used in many fields such as microwave communication, microwave guidance, navigation, telemetry, remote control, satellite communication, and military electronic countermeasures, and the requirements for the volume and performance of microwave filters are getting higher and higher. A planar structure filter based on IPD technology has the advantages of easy integration with active devices and small size, and is widely used. In recent years, with the rapid development of microwave technology, the trend of miniaturization of components has become more and more obvious, and higher and higher requirements have been put forward for microstrip line filters. Researching a new type of filter that is easy to integrate, small in size, and has good filter performance is one of the technical problems that the existing microstrip line filters urgently need to solve.

[0003] The existing IPD technology filter types include hairpin type, comb type, interdigital type, parallel coupling type and other types. When the filter order is the same, the parallel coupling type filter is larger in size. The hairpin microstrip line filter is an improved filter based on the parallel coupling type filter, and still has the disadvantage of being large in size. The comb line and interdigital filters have the advantage of small size, but are affected by the parasitic inductance of the grounding hole, showing the phenomenon of low-frequency upwarping and high-frequency downwarping. There are the disadvantages of poor low-frequency rectangular coefficient in the stopband, high insertion loss on the high-frequency side in the passband, and large fluctuations in the band.

[0004] Patent CN201910828684.7 in the prior art proposes that a U-shaped bandpass filter can improve the effect of the filter S21 parameter rising at low frequencies and falling at high frequencies, thereby improving the low-frequency rectangular coefficient of the stopband and reducing the fluctuations in the passband and the insertion loss at high frequencies. However, the rectangular coefficient on the high-frequency side is still poor. Summary of the invention

[0005] In view of the above problems, the present invention is proposed to provide a cross-coupled bandpass filter based on IPD technology that overcomes the above problems or at least partially solves the above problems.

[0006] According to one aspect of the present invention, a cross-coupled bandpass filter based on IPD technology is provided, the filter comprising: a substrate, a metal routing layer; metal electrodes and capacitors are made on one side of the substrate, and the other side is a gold-clad ground plane; a feeder, a first feeder port 1 and a second feeder port 9 are respectively arranged on the metal routing layer; one end of the feeder is connected to the resonator, and the other end is connected to the GSG port for testing; the structure of the filter is that the quarter-wavelength microstrip line in the middle of the fifth-order combline filter is replaced by a half-wavelength U-shaped microstrip line.

[0007] Optionally, the resonator adopts a bandpass filter with a center frequency of 11 GHz, and the length of a quarter-wavelength resonator is 1.2 mm; the length of a half-wavelength resonator is 2.4 mm.

[0008] Optionally, the resonator specifically includes: a first resonator, a second resonator, a third resonator, a fourth resonator and a fifth resonator; the first resonator includes a second transmission line 2 and a capacitor, one end of the second transmission line 2 is provided with a metal through hole, the metal through hole is connected to the back metal, the other end of the second transmission line 2 is connected to one layer of metal of the capacitor, and the other layer of metal of the capacitor is connected to the corresponding metal through hole; the second resonator includes a third transmission line 3 and a capacitor, one end of the third transmission line 3 is provided with a metal through hole, the metal through hole is connected to the back metal, the other end of the third transmission line 3 is connected to one layer of metal of the capacitor, and the other layer of metal of the capacitor is connected to the corresponding metal through hole; the third resonator includes a fourth transmission line 4, a fifth transmission line 5, a sixth transmission line 6 and a grounded capacitor; the fourth transmission line 4 and the sixth transmission line 6 are connected to the grounded capacitor; The fifth transmission line 5 is connected to the fourth transmission line 4 and the sixth transmission line 6 respectively; the fourth resonator is the same as the second resonator, including a seventh transmission line 7, one end of the seventh transmission line 7 is provided with a metal through hole, the metal through hole is connected to the back metal, the other end of the seventh transmission line 7 is connected to one layer of metal of the capacitor, and the other layer of metal of the capacitor is connected to the corresponding metal through hole; the fifth resonator is the same as the first resonator, an eighth transmission line 8 and a capacitor, one end of the eighth transmission line 8 is provided with a metal through hole, the metal through hole is connected to the back metal, the other end of the eighth transmission line 8 is connected to one layer of metal of the capacitor, and the other layer of metal of the capacitor is connected to the corresponding metal through hole; a capacitor group C2 is connected between the third transmission line 3 and the seventh transmission line 7 through the tenth transmission line 10, and the capacitor group C2 includes a plurality of capacitors connected in series.

[0009] Optionally, the GSG structure is: connected to the first feeder port 1 and the second feeder port 9 for transmitting electromagnetic wave signals; the first feeder port 1 is connected to the first resonator for feeding in or out electromagnetic wave signals; the second feeder port 9 is connected to the fifth resonator for feeding in or out electromagnetic wave signals; the second resonator is arranged between the first resonator and the third resonator; the fourth resonator is between the third resonator and the fifth resonator; the third resonator is arranged between the second resonator and the fourth resonator; the first resonator, the second resonator, the fourth resonator, and the fifth resonator are all quarter-wavelength microstrip lines, and the first resonator and the fifth resonator are mirror-symmetrical structures, the second resonator and the fourth resonator are mirror-symmetrical structures, and the third resonator is composed of a half-wavelength microstrip line, and the whole is a U-shaped structure.

[0010] Optionally, the second transmission line 2 , the third transmission line 3 , the fourth transmission line 4 , the sixth transmission line 6 , the seventh transmission line 7 and the eighth transmission line 8 are parallel to each other.

[0011] Optionally, the plurality of metal through holes G1 have the same size and are all gold-plated cylindrical through holes, and are used for through-hole grounding of the first resonator, the second resonator, the third resonator, the fourth resonator, and the fifth resonator.

[0012] Optionally, the substrate is a GaAs substrate with a relative dielectric constant of 12.9 and a thickness of 100 μm.

[0013] Optionally, the thickness of the upper and lower electrodes of the capacitor are 4μm and 1μm respectively, the capacitor dielectric layer material is SiN, the relative dielectric constant is 6.9, and the thickness is 200nm. The layer between the M1 metal layer and the M2 metal layer is polyimide, with a thickness of 2um and a relative dielectric constant of 2.9.

[0014] Optionally, the second transmission line 2 , the third transmission line 3 , the fourth transmission line 4 , the sixth transmission line 6 , the seventh transmission line 7 and the eighth transmission line 8 have the same width, and an impedance of 50 ohms.

[0015] The present invention provides a cross-coupled bandpass filter based on IPD technology, the filter comprising: a substrate, a metal wiring layer; metal electrodes and capacitors are made on one side of the substrate, and the other side is a gold-clad ground plate; a feeder, a first feeder port and a second feeder port are respectively arranged on the metal wiring layer; one end of the feeder is connected to a resonator, and the other end is connected to a GSG port for testing; the structure of the filter is that a quarter-wavelength microstrip line in the middle of a fifth-order combline filter is replaced by a half-wavelength U-shaped microstrip line.

[0016] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0018] Figure 1 A schematic diagram of the structure of a cross-coupled bandpass filter based on IPD technology provided by an embodiment of the present invention.

[0019] Figure 2 A schematic diagram comparing the simulation results of the bandpass filter of the novel structure provided in the embodiment of the present invention with the simulation results of the original bandpass filter. DETAILED DESCRIPTION

[0020] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0021] 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.

[0022] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0023] like Figure 1 As shown, the present invention adopts a GaAs substrate with a relative dielectric constant of 12.9 and a thickness of 100μm, and the metal material is Au as the electrode of the resonator and the upper and lower electrodes of the capacitor. The thickness of the resonator is 4μm, and the thicknesses of the upper and lower electrodes of the capacitor are 4μm and 1μm respectively. The capacitor dielectric layer material is SiN, with a relative dielectric constant of 6.9 and a thickness of 200nm. Between the M1 layer metal and the M2 layer metal is polyimide, with a thickness of 2μm and a relative dielectric constant of 2.9.

[0024] The overall structure of the present invention is that the quarter-wavelength microstrip line in the middle of the fifth-order comb line filter is replaced with a half-wavelength U-shaped microstrip line, and the U-shaped microstrip line is used to reduce the influence of the parasitic inductance of the through hole on the microstrip line filter. The total length of the resonator of the present invention is as follows: for a bandpass filter with a center frequency of 11 GHz, the length of the quarter-wavelength resonator is 1.2 mm, while the length of a conventional quarter-wavelength resonator is 4.4 mm; the length of the half-wavelength resonator of the present invention is 2.4 mm, and the length of the conventional half-wavelength resonator is 4.8 mm; the length of the resonator of the present invention is approximately less than half of that of the conventional resonator, and the volume of the filter is reduced by approximately less than half.

[0025] The present invention connects a capacitor between the second resonator and the fourth resonator to increase the capacitive coupling between the second and fourth resonators, thereby realizing the generation of a zero point on the high frequency side and significantly improving the rectangular coefficient on the high frequency side. Figure 2 shown.

[0026] like Figure 1 As shown, the planar microstrip bandpass filter based on the hybrid structure of comb lines and hairpin lines provided in this embodiment is made of metal electrodes and capacitors on a GaAs substrate with holes punched based on semiconductor technology, the other side is a gold-clad ground plate, and the middle is a GaAs substrate.

[0027] The metal wiring layer is provided with a first feeder port 1 and a second feeder port 9 respectively. One end of the feeder is connected to the resonator, and the other end is connected to the GSG port for testing.

[0028] The first resonator includes a second transmission line 2 and a capacitor C1. A metal through hole G1 is provided at the end of the second transmission line 2, and the capacitor C1 is connected to the corresponding metal through hole G1.

[0029] The second resonator has a similar structure to the first resonator, including a third transmission line 3 and a capacitor C1. A metal through hole G1 is provided at the end of the third transmission line 3, and the capacitor C1 is connected to the corresponding metal through hole G1.

[0030] The third resonator comprises a fourth transmission line 4, a fifth transmission line 5, a sixth transmission line 6 and a capacitor C1, wherein the fourth transmission line 4 and the sixth transmission line 6 are connected to the capacitor C1, and the fifth transmission line 5 is connected to the fourth transmission line 4 and the sixth transmission line 6 respectively.

[0031] The fourth resonator is the same as the second resonator, including a seventh transmission line 7, one end of which is provided with a metal through hole, the metal through hole is connected to the back metal, the other end of the seventh transmission line 7 is connected to one layer of metal of the capacitor, and the other layer of metal of the capacitor is connected to the corresponding metal through hole.

[0032] The fifth resonator is the same as the first resonator, with an eighth transmission line 8 and a capacitor C1. One end of the eighth transmission line 8 is provided with a metal through hole, and the metal through hole is connected to the back metal. The other end of the eighth transmission line 8 is connected to one layer of metal of the capacitor, and the other layer of metal of the capacitor is connected to the corresponding metal through hole.

[0033] The capacitors used are the same, the sizes of the metal through holes are the same, the capacitor is C1, and the metal through hole is G1.

[0034] The GSG structure is connected to the first feeder port 1 and the second feeder port 9 respectively for transmitting electromagnetic wave signals; the first feeder port 1 is connected to the first resonator for feeding in or out electromagnetic wave signals.

[0035] The second feeder port 9 is connected to the fifth resonator and is used for feeding in or out electromagnetic wave signals.

[0036] The second resonator is disposed between the first resonator and the third resonator.

[0037] The fourth resonator is between the third resonator and the fifth resonator.

[0038] The third resonator is disposed between the second resonator and the fourth resonator.

[0039] The first resonator, the second resonator, the fourth resonator and the fifth resonator are all quarter-wavelength microstrip lines, and the first resonator and the fifth resonator are mirror-symmetrical structures, the second resonator and the fourth resonator are mirror-symmetrical structures, and the third resonator is composed of a half-wavelength microstrip line, and the overall structure is U-shaped.

[0040] The second transmission line 2, the third transmission line 3, the fourth transmission line 4, the sixth transmission line 6, the seventh transmission line 7, and the eighth transmission line 8 are parallel to each other; G1 has the same size and is a gold-plated cylindrical through hole used for via grounding of the first resonator, the second resonator, the fourth resonator, and the fifth resonator.

[0041] A capacitor group C2 is connected between the third transmission line 3 and the seventh transmission line 7 via a tenth transmission line 10 , and the capacitor group C2 includes a plurality of capacitors connected in series.

[0042] The length and width of the first feeder port 1 and the second feeder port 9 are the same.

[0043] The second transmission line 2 , the third transmission line 3 , the fourth transmission line 4 , the sixth transmission line 6 , the seventh transmission line 7 , and the eighth transmission line 8 have the same width and an impedance of 50 ohms.

[0044] A layer of metal is grown on the GaAs substrate as a seed layer, and then photolithography, development, and electroplating are performed to form the bottom electrode of the capacitor.

[0045] Sputter 200nm thick SiN material as the dielectric layer of the capacitor.

[0046] A polyimide layer is made as a dielectric material to simulate the intersection of crossed electrodes.

[0047] A layer of metal is then prepared as a seed layer, and photolithography, development, and electroplating are performed to form the top electrode of the capacitor and the resonator electrode.

[0048] A through hole is made on the back of the GaAs substrate, and a metal material such as copper or gold is used to fill the through hole to form a ground terminal, thereby forming a ground electrode of the capacitor and a ground electrode of the quarter-wavelength resonator.

[0049] A metal layer is grown on the back of GaAs and then electroplated.

[0050] The structure of the present invention is as follows Figure 1 As shown, the structure is symmetrical, the electrode width is 0.07mm, and the specific parameters of the length are as follows: for the bandpass filter with a center frequency of 11G, the capacitance value is 0.27pF, and the quarter-wavelength resonator electrode length is about 1.2mm; the total capacitance of the capacitor group consisting of four capacitors is 0.045pF, and each capacitor is 0.18pF.

[0051] Beneficial effect: The present invention connects a grounding capacitor in series at the ground capacitance end of the resonator, increases the ground capacitance of the resonator, reduces the length of the resonator, and achieves the goal of reducing the volume of the filter.

[0052] The above specific implementation methods further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific implementation methods of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A cross-coupled bandpass filter based on IPD technology, characterized in that: The filter comprises: a substrate, a metal wiring layer; metal electrodes and capacitors are made on one side of the substrate, and the other side is a gold-covered ground plane; a feeder, a first feeder port (1) and a second feeder port (9) are respectively arranged on the metal wiring layer; one end of the feeder is connected to the resonator, and the other end is connected to the GSG port for testing; the structure of the filter is that the quarter-wavelength microstrip line in the middle of the fifth-order comb line filter is replaced with a half-wavelength U-shaped microstrip line; The resonator uses a bandpass filter with a center frequency of 11 GHz, a quarter-wavelength resonator length of 1.2 mm, and a half-wavelength resonator length of 2.4 mm; The resonator specifically comprises: a first resonator, a second resonator, a third resonator, a fourth resonator and a fifth resonator; the first resonator comprises a second transmission line (2) and a capacitor, one end of the second transmission line (2) is provided with a metal through hole, the metal through hole is connected to the back metal, the other end of the second transmission line (2) is connected to one layer of metal of the capacitor, and the other layer of metal of the capacitor is connected to the corresponding metal through hole; the second resonator comprises a third transmission line (3) and a capacitor, one end of the third transmission line (3) is provided with a metal through hole, the metal through hole is connected to the back metal, the other end of the third transmission line (3) is connected to one layer of metal of the capacitor, and the other layer of metal of the capacitor is connected to the corresponding metal through hole; the third resonator comprises a fourth transmission line (4), a fifth transmission line (5), a sixth transmission line (6) and a grounded capacitor; the fourth transmission line (4) and the sixth transmission line (6) are connected to the grounded capacitor; the fifth transmission line ( 5) are respectively connected to the fourth transmission line (4) and the sixth transmission line (6); the fourth resonator is the same as the second resonator, including a seventh transmission line (7), one end of the seventh transmission line (7) is provided with a metal through hole, the metal through hole is connected to the back metal, the other end of the seventh transmission line (7) is connected to one layer of metal of the capacitor, and the other layer of metal of the capacitor is connected to the corresponding metal through hole; the fifth resonator is the same as the first resonator, an eighth transmission line (8), a tenth transmission line (10) and a capacitor, one end of the eighth transmission line (8) is provided with a metal through hole, the metal through hole is connected to the back metal, the other end of the eighth transmission line (8) is connected to one layer of metal of the capacitor, and the other layer of metal of the capacitor is connected to the corresponding metal through hole; a capacitor group C2 is connected between the third transmission line (3) and the seventh transmission line (7) through the tenth transmission line (10), and the capacitor group C2 includes a plurality of capacitors connected in series; The structure of the GSG is as follows: it is connected to a first feeder port (1) and a second feeder port (9) for transmitting electromagnetic wave signals; the first feeder port (1) is connected to the first resonator for feeding in or feeding out electromagnetic wave signals; the second feeder port (9) is connected to the fifth resonator for feeding in or feeding out electromagnetic wave signals; the second resonator is arranged between the first resonator and the third resonator; the fourth resonator is between the third resonator and the fifth resonator; the third resonator is arranged between the second resonator and the fourth resonator; the first resonator, the second resonator, the fourth resonator and the fifth resonator are all quarter-wavelength microstrip lines, and the first resonator and the fifth resonator are in a mirror-symmetrical structure, the second resonator and the fourth resonator are in a mirror-symmetrical structure, and the third resonator is composed of a half-wavelength microstrip line, and the whole is in a U-shaped structure; The second transmission line (2), the third transmission line (3), the fourth transmission line (4), the sixth transmission line (6), the seventh transmission line (7) and the eighth transmission line (8) are parallel to each other; The multiple metal through holes G1 have the same size and are all gold-plated cylindrical through holes, and are used for through-hole grounding of the first resonator, the second resonator, the third resonator, the fourth resonator, and the fifth resonator.

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

3. The cross-coupled bandpass filter based on IPD technology according to claim 1, characterized in that: The thickness of the upper and lower electrodes of the capacitor are 4 μm and 1 μm respectively. The capacitor dielectric layer material is SiN with a relative dielectric constant of 6.9 and a thickness of 200 nm. The layer between the M1 metal layer and the M2 metal layer is polyimide with a thickness of 2 μm and a relative dielectric constant of 2.

9.

4. The cross-coupled bandpass filter based on IPD technology according to claim 3, characterized in that: The second transmission line (2), the third transmission line (3), the fourth transmission line (4), the sixth transmission line (6), the seventh transmission line (7) and the eighth transmission line (8) have the same width and an impedance of 50 ohms.

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