SIR interdigital coupling type integrated filtering balun based on TSV and design method thereof
By designing a TSV-based SIR interdigital coupled integrated filter balun, the problems of narrow bandwidth and large area of traditional filter balun devices are solved, realizing a miniaturized and high-performance filter balun device with good frequency selectivity and balanced signal conversion function.
Patent Information
- Application Number
- CN202511039658.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-28
- Publication Date
- 2025-10-28
AI Technical Summary
Traditional filter balun devices have narrow bandwidth and large footprint, which affects system performance and integration.
A TSV-based SIR interdigitated coupling integrated filter balun is adopted. By introducing TSV technology into the resonator and combining half-wavelength and quarter-wavelength resonators, filtering and balanced signal conversion are integrated. The impedance ratio and resonator length are adjusted by utilizing the SIR structure to reduce the device size and increase the transmission rate.
A miniaturized filter balun device was achieved, which suppressed parasitic effects, has good frequency selectivity and balanced signal conversion performance, is easy to integrate, and reduces signal transmission loss.
Smart Images
Figure CN120856097A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of passive electronic device technology, and relates to a TSV-based SIR interdigitated coupling integrated filter balun. This invention also relates to a design method for a TSV-based SIR interdigitated coupling integrated filter balun. Background Technology
[0002] A balun is a key component in radio frequency (RF) systems, crucial for converting between single-port and differential signals, and essential for ensuring system anti-interference capability and signal integrity. Filters selectively pass through and suppress input signals, achieving frequency domain signal purification. In traditional RF receiver front-end systems, the received unbalanced signal is filtered to suppress spurious signals before being converted into a balanced signal by a cascaded balun. While this traditional cascaded architecture integrates filtering and balanced signal conversion, the introduced additional losses and parasitic effects significantly impact system performance. To meet the demands of integration, integrated balun components combining balun and filtering functions offer a new approach to improving system integration and reducing signal transmission loss. Currently, there are two main implementation methods for baluns: one uses lumped circuits, which offer a compact structure but are extremely sensitive to capacitor and inductor values and have a narrow bandwidth; the other utilizes microstrip and slotted line transition structures, but this structure requires high symmetry and occupies a large area. Summary of the Invention
[0003] The purpose of this invention is to provide a TSV-based SIR interdigitated coupling integrated filter balun, which solves the problems of narrow bandwidth and large area occupation of traditional devices.
[0004] The second objective of this invention is to provide a design method for a TSV-based SIR interdigitated coupled integrated filter balun.
[0005] The first technical solution adopted in this invention is a TSV-based SIR interdigitally coupled integrated filter balun, which includes, from top to bottom, a top PI dielectric, a silicon substrate and a bottom PI dielectric. The top PI dielectric contains a resonator RDL, the bottom PI dielectric contains a connecting line RDL, and the silicon substrate contains a TSV.
[0006] The first technical solution of this invention is further characterized by: The resonator RDL comprises six components, namely the first resonator RDL, the second resonator RDL, the third resonator RDL, the fourth resonator RDL, the fifth resonator RDL, and the sixth resonator RDL. The high-impedance end of the first resonator RDL is connected to one end of the connecting line RDL via a TSV, and the other end of the connecting line RDL is connected to the fourth resonator RDL via a TSV, forming an impedance transformation structure of microstrip line-CPW transition, which together constitute a half-wavelength resonator. The high-impedance ends of the second, third, fifth, and sixth resonators RDL are respectively connected to a grounded metal plate via TSVs, each constituting a quarter-wavelength resonator.
[0007] The first resonator RDL, the second resonator RDL, and the third resonator RDL are arranged in parallel and staggered order; the fourth resonator RDL, the fifth resonator RDL, and the sixth resonator RDL are arranged in parallel and staggered order. The first resonator RDL and the fourth resonator RDL are placed side by side symmetrically, the second resonator RDL and the fifth resonator RDL are placed side by side symmetrically, and the third resonator RDL and the sixth resonator RDL are placed side by side symmetrically.
[0008] The fourth resonator RDL is coupled with the input feed line to transmit signals, and the input feed line leads out to the input port Port1; the third resonator RDL is coupled with the first output feed line to transmit signals, and the first output feed line leads out to the output port Port2; the sixth resonator RDL is coupled with the second output feed line to transmit signals, and the second output feed line leads out to the output port Port3.
[0009] The connecting line RDL is located on the grounded metal plate between the first resonator RDL and the fourth resonator RDL.
[0010] Silicon dioxide insulation is provided between the top PI dielectric and the silicon substrate, and between the silicon substrate and the bottom PI dielectric.
[0011] The first resonator RDL, the second resonator RDL, the third resonator RDL, the fourth resonator RDL, the fifth resonator RDL, and the sixth resonator RDL are all composed of two impedance units with different impedances directly cascaded together.
[0012] The second technical solution adopted in this invention is a design method for an integrated filter balun based on TSV and SIR interdigital coupling, wherein the electrical length of the SIR structure... and resonant frequency Represented as: (1) (2).
[0013] The beneficial effect of this invention is that it utilizes the characteristic of equal amplitude and opposite phase electric fields on both sides of the center point of a half-wavelength transmission line, and sets up multi-line coupled quarter-wavelength resonators on both sides to realize a multi-functional fusion device that integrates filtering and balanced signal conversion functions to achieve the filtering balun function. The quarter-wavelength resonator adopts a TSV-based SIR (stepped impedance resonator) structure, which has the advantage of being able to achieve a higher impedance ratio R... Z Adjusting the resonator length and the position of the spurious frequency increases design freedom. The half-wavelength resonator uses a TSV to connect the bottom CPW (coplanar waveguide) low-impedance transmission line and the top stepped impedance transmission line. A multi-segment stepped impedance structure is achieved through a CPW-microstrip line transition, effectively reducing size while maintaining structural symmetry. Introducing TSV technology further reduces size while utilizing its excellent electrical characteristics to increase transmission rate, overcoming the limitation of traditional devices being unsuitable for millimeter waves. This invention designs a TSV-based transition line structure and SIR structure, which are then integrated with a coupled filter balun to achieve a small and high-performance filter balun. This balun device simultaneously achieves frequency selection and balanced signal conversion functions. Compared with traditional models, it effectively suppresses parasitic effects and has a simple structure, making it easy to integrate and miniaturize. Attached Figure Description
[0014] Figure 1(a) is the circuit diagram of a third-order interdigital filter; Figure 1(b) shows the circuit diagram of a third-order filter balun; Figure 2 This is a three-dimensional view of the SIR interdigitally coupled integrated filter balun based on TSV of this invention; Figure 3 This is a top view of the SIR interdigitally coupled integrated filter balun based on TSV of the present invention; Figure 4 This is a top view of the grounded metal plate of the SIR interdigital coupling integrated filter balun based on TSV of the present invention. Figure 5 This is a longitudinal cross-sectional view of the second resonator RDL and the corresponding TSV of the SIR interdigitally coupled integrated filter balun based on TSV of this invention. Figure 6 These are the S-parameter simulation results of the SIR interdigitally coupled integrated filter balun based on TSV according to this invention; Figure 7 The simulation results show the phase difference and amplitude imbalance of the SIR interdigital coupled integrated filter balun based on TSV according to this invention.
[0015] In the figure, 1. First resonator RDL, 2. Second resonator RDL, 3. Third resonator RDL, 4. Fourth resonator RDL, 5. Fifth resonator RDL, 6. Sixth resonator RDL, 7. Input feed line, 8. First output feed line, 9. Second output feed line, 10. TSV, 11. Top layer PI dielectric, 12. Silicon substrate, 13. Grounding metal plate, 14. Bottom layer PI dielectric, 15. Connector RDL, 16. TSV copper pillar, 17. Silicon dioxide insulating layer. Detailed Implementation
[0016] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.
[0017] Example 1 This invention relates to a TSV-based SIR interdigital coupled integrated filter balun, which combines a coupled filter and a balun. Each resonator uses a TSV-based SIR, and the overall structure is perfectly symmetrical. Through a specific electromagnetic coupling mechanism, it achieves a superior multifunctional filter balun fusion device. The circuit principle of this invention is shown in Figure 1. Figure 1(a) shows a third-order interdigital filter. This filter forms a specific electromagnetic coupling relationship between the input feed line S, three quarter-wavelength resonators R1, R2, and R3, and the output feed line L, generating corresponding frequency response characteristics and realizing the filtering function. Where k... 12 k represents the coupling coefficient between R1 and R2. 23 k represents the coupling coefficient between R2 and R3. s1 k represents the coupling coefficient between S and R1. 3L This represents the coupling coefficient between L and R3. Figure 1(b) shows the quarter-wavelength resonator R1 of the interdigital filter in Figure 1(a) being changed to a half-wavelength resonator. Utilizing the symmetrical characteristic of a half-wavelength resonator where the electric fields on either side of the center point are opposite in direction and equal in magnitude, a coupled resonator as shown in Figure 1(a) is symmetrically constructed on both sides of its center point. Lp and Lm represent two balanced output feed lines. To evenly distribute the power of the two branches, The coupling coefficient between R2 and R2 is changed from the original k 12 Adjusted to This design satisfies the balun characteristics of equal amplitude and phase inversion balance conversion, and also achieves filtering performance similar to that in Figure 1(a), ultimately realizing a three-port coupled filtering balun functional device.
[0018] Example 2 The design process of the SIR interdigital coupled integrated filter balun based on TSV in this invention is as follows: To determine the structural parameters of the quarter-wavelength resonators R1, R2, and R3, R1, R2, and R3 in this invention all adopt an SIR structure. Their electrical lengths and resonant frequencies can be obtained through the following formulas. Where θ is the electrical length of R1, R2, and R3, Z1 and θ1 are the impedance and electrical length of the high-impedance portions of R1, R2, and R3, respectively, Z2 is the impedance of the low-impedance portions of R1, R2, and R3, and R... Z The impedance ratio is Z2 / Z1. f 0 is the resonant frequency, c is the speed of light, and λ is the velocity of light. g Waveguide wavelength The effective dielectric constant. The electrical length θ and resonant frequency of the quarter-wavelength resonator R1, R2, and R3. f 0 is represented as:
[0019]
[0020] To design filtering performance, the coupling coefficient of the filter... and external quality factors It can be expressed by the following formula. Where, R represents a quarter-wavelength resonator i With R i+1 The coupling coefficients between them, i=1, 2; represents the low-pass prototype of a third-order Chebyshev filter, i = 0, 1, 2, 3; FBW represents the fractional bandwidth of the filter; external quality factor. With k s1 k 3L This determines the power coupling strength between the input feed line S and R1, and between the output feed line L and R3.
[0021]
[0022]
[0023] The filter incorporates a balun characteristic, replacing the quarter-wavelength resonator R1 with a half-wavelength resonator. ,from The circuit is symmetrically divided into two branches to distribute power evenly between them. The coupling coefficient between R2 and R2 is determined by k 12 Adjusted to .
[0024] Example 3 like Figure 2As shown, the structure of this invention, from top to bottom, consists of a top PI (polyimide) dielectric 11, a silicon substrate 12, and a bottom PI dielectric 14. A layer of RDL metal is disposed in the top PI dielectric 11, including each resonator RDL, input feed line, output feed line, input port, and output port. A grounding metal plate 13 and connecting lines RDL 15 are disposed in the bottom PI dielectric. TSV 10 is embedded in the silicon substrate.
[0025] Example 4 like Figure 3 As shown, the first resonator RDL1, the second resonator RDL2, the third resonator RDL3, the fourth resonator RDL4, the fifth resonator RDL5, and the sixth resonator RDL6 are all composed of two impedance units with different impedances directly cascaded together. The impedance value of the high impedance unit is Z1, and the impedance value of the low impedance unit is Z2.
[0026] The low-impedance terminals of the first resonator RDL1, the second resonator RDL2, the third resonator RDL3, the fourth resonator RDL4, the fifth resonator RDL5, and the sixth resonator RDL6 are all open-circuited. The high-impedance terminal of the first resonator RDL1 is connected to the connecting line RDL15 through TSV10, and the other end of the connecting line RDL15 is connected to the fourth resonator RDL4 through TSV10, realizing the impedance transformation structure of the microstrip line-CPW transition, and together forming a half-wavelength resonator. The high-impedance terminals of the second resonator RDL2, the third resonator RDL3, the fifth resonator RDL5, and the sixth resonator RDL6 are connected to the grounded metal plate 13 through TSV10, forming quarter-wavelength resonators respectively.
[0027] Example 5 The first resonator RDL1, the second resonator RDL2, and the third resonator RDL3 are arranged in parallel and staggered order, with energy transfer between adjacent resonators via electromagnetic coupling. The fourth resonator RDL4, the fifth resonator RDL5, and the sixth resonator RDL6 are also arranged in parallel and staggered order, with energy transfer between adjacent resonators via electromagnetic coupling. The first resonator RDL1 and the fourth resonator RDL4 are placed side-by-side symmetrically, as are the second resonator RDL2 and the fifth resonator RDL5, and the third resonator RDL3 and the sixth resonator RDL6.
[0028] Example 6 Input feed line 7 couples with the fourth resonator RDL4 to transmit signals, and the input feed line leads out to input port Port1. First output feed line 8 couples with the third resonator RDL3 to transmit signals, and the first output feed line 8 leads out to output port Port2. Second output feed line 9 couples with the sixth resonator RDL6 to transmit signals, and the second output feed line 9 leads out to output port Port3.
[0029] like Figure 4 As shown, a hollowed-out area is made in the region between the first resonator RDL1 and the fourth resonator RDL4, corresponding to the area of the grounding metal plate 13, to accommodate the CPW transmission line type connecting line RDL15.
[0030] like Figure 5 As shown, thin silicon dioxide insulating layers are disposed between the top PI dielectric 11 and the silicon substrate 12, and between the silicon substrate 12 and the bottom PI dielectric 14, to achieve electrical isolation. A TSV 10 in the silicon substrate connects the top RDL in the bottom PI dielectric 11 and the bottom RDL in the bottom PI dielectric 14. The TSV 10 includes a TSV copper pillar 16 and a silicon dioxide insulating layer 17 surrounding the TSV copper pillar 16.
[0031] The important dimensions in the model are labeled as follows: The TSV copper pillar 16 has a radius of 3.5 μm and a height of 100 μm. The silicon dioxide insulating layer 17 surrounding the TSV copper pillar 16 has a thickness of 1.5 μm. The thickness of the top RDL and the bottom grounding metal plate is 5 μm. The thickness of the silicon substrate 12 is 98 μm. The thickness of the silicon dioxide insulating layer 17 between the top PI dielectric 11 and the silicon substrate 12, and between the top PI dielectric 14 and the silicon substrate 12, is 1 μm.
[0032] The low-impedance portions of the first resonator RDL1, second resonator RDL2, third resonator RDL3, fourth resonator RDL4, fifth resonator RDL5, and sixth resonator RDL6 have a width of 40.2 μm and a length of 109.4 μm, while the high-impedance portions have a width of 10 μm. The high-impedance portions of the first resonator RDL1 and fourth resonator RDL4 have a length of 170.5 μm. The high-impedance portions of the second resonator RDL2 and fifth resonator RDL5 have a length of 138.5 μm. The high-impedance portions of the second resonator RDL2 and fifth resonator RDL5 have a length of 185.5 μm.
[0033] The spacing between the first resonator RDL1 and the second resonator RDL2, and the spacing between the fourth resonator RDL4 and the fifth resonator RDL5, are both 102.3 μm. The spacing between the second resonator RDL2 and the third resonator RDL3, and the spacing between the fifth resonator RDL5 and the sixth resonator RDL6, are both 97.5 μm. The open-circuit terminal of the first resonator RDL1 is located 15 μm after the short-circuit terminal of the second resonator RDL2, and the open-circuit terminal of the fourth resonator RDL4 is located 15 μm before the short-circuit terminal of the fifth resonator RDL5.
[0034] The input feed line 7 has a width of 8 μm and a length of 294.9 μm. The first output feed line 8 and the second output feed line 9 have a width of 10 μm and a length of 294.9 μm. The input port Port1, the first output port Port2, and the second output port Port3 all have a width of 34.5 μm and a length of 40 μm. The distance between the input feed line 7 and the second resonator RDL2 is 19.4 μm, and the distance between the first output feed line 8 and the third resonator RDL3, and the distance between the second output feed line 9 and the sixth resonator RDL6 are both 47.4 μm.
[0035] The length of the metal removed from the grounding metal plate is 70μm, and the width is 26μm. The connecting line RDL is 60μm long and 10μm wide, and is located at the center of the through hole removed from the grounding metal plate.
[0036] Example 7 like Figure 6 These are the S-parameter simulation results obtained from electromagnetic simulation in HFSS, which can intuitively characterize the filtering performance of the filtering balun. S11 represents the reflection coefficient of Port1, used to measure the matching degree of Port1. S21 represents the transmission coefficient from Port1 to Port2, used to measure the transmission efficiency and amplitude of the signal from Port1 to Port2. S31 represents the transmission coefficient from Port1 to Port3, used to measure the transmission efficiency and amplitude of the signal from Port1 to Port3. Figure 6 It can be seen that the passband of the present invention is 58.2~74.5GHz, and the S11 in the passband is less than -16dB, indicating that the port matching degree of the present invention is good. The out-of-band suppression of both low frequency and high frequency can reach -30dB, indicating that it has good frequency selection and anti-interference capability.
[0037] like Figure 7 This invention presents the phase / amplitude imbalance results obtained through electromagnetic simulation in HFSS, which can intuitively characterize the balance performance of the filter balun. Amplitude imbalance represents the difference in amplitude between the signals at the two balanced output ports. Phase imbalance represents the degree to which the phases of the signals at the two balanced output ports deviate from the ideal 180°. Figure 7 It can be seen that within the passband of the filter, the amplitude imbalance is less than 1.35dB and the phase imbalance is less than 7°. In the frequency range of 60.8~74.5GHz, the amplitude imbalance can be less than 0.5dB, exhibiting excellent balanced conversion performance. The S21 parameter in the passband is approximately -5dB, meeting the design requirements of the filter balun. This proves the effectiveness of the structural design of this invention.
Claims
1. A TSV-based SIR interdigital coupled integrated filter balun, characterized in that: The structure consists of a top PI dielectric (11), a silicon substrate (12), and a bottom PI dielectric (14) from top to bottom. The top PI dielectric (11) contains a resonator RDL, the bottom PI dielectric (14) contains a connecting line RDL (15), and the silicon substrate (12) contains a TSV (10).
2. The TSV-based SIR interdigitated coupled integrated filter balun according to claim 1, characterized in that: The resonator RDL includes six components, namely the first resonator RDL (1), the second resonator RDL (2), the third resonator RDL (3), the fourth resonator RDL (4), the fifth resonator RDL (5), and the sixth resonator RDL (6). The high impedance end of the first resonator RDL (1) is connected to one end of the connecting line RDL (15) through TSV (10), and the other end of the connecting line RDL (15) is connected to the fourth resonator RDL (4) through TSV (10), forming an impedance transformation structure of microstrip line-CPW transition, which together constitute a half-wavelength resonator. The high-impedance ends of the second resonator RDL (2), the third resonator RDL (3), the fifth resonator RDL (5), and the sixth resonator RDL (6) are connected to the grounded metal plate (13) through TSV (10) respectively, forming quarter-wavelength resonators.
3. The TSV-based SIR interdigitated coupled integrated filter balun according to claim 2, characterized in that: The first resonator RDL (1), the second resonator RDL (2), and the third resonator RDL (3) are arranged in parallel and staggered order; The fourth resonator RDL (4), the fifth resonator RDL (5) and the sixth resonator RDL (6) are arranged in parallel and staggered order. The first resonator RDL (1) and the fourth resonator RDL (4) are placed side by side symmetrically. The second resonator RDL (2) and the fifth resonator RDL (5) are placed side by side symmetrically. The third resonator RDL (3) and the sixth resonator RDL (6) are placed side by side symmetrically.
4. The TSV-based SIR interdigital coupled integrated filter balun according to claim 3, characterized in that: The fourth resonator RDL (4) is coupled with the input feed line (7) to transmit signals, and the input feed line (7) leads out to the input port Port1; the third resonator RDL (3) is coupled with the first output feed line (8) to transmit signals, and the first output feed line (8) leads out to the output port Port2; the sixth resonator RDL (6) is coupled with the second output feed line (9) to transmit signals, and the second output feed line (9) leads out to the output port Port3.
5. The SIR interdigital coupled integrated filter balun based on TSV according to claim 4, characterized in that: The connecting line RDL (15) is located on the grounded metal plate (13) between the first resonator RDL (1) and the fourth resonator RDL (4).
6. The TSV-based SIR interdigitated coupled integrated filter balun according to claim 4, characterized in that: Silicon dioxide insulation is provided between the top PI medium (11) and the silicon substrate (12), and between the silicon substrate (12) and the bottom PI medium (14).
7. The TSV-based SIR interdigitated coupled integrated filter balun according to claim 4, characterized in that: The first resonator RDL (1), the second resonator RDL (2), the third resonator RDL (3), the fourth resonator RDL (4), the fifth resonator RDL (5), and the sixth resonator RDL (6) are all composed of two impedance units with different impedances directly cascaded together.
8. A TSV-based SIR interdigital coupled integrated filter balun design method, characterized in that: The electrical length of the SIR structure and resonant frequency Represented as: （1） （2） Among them, R Z Let Z2 / Z1 be the impedance ratio, where Z1 and θ1 are the impedance and electrical length of the high-impedance portions of R1, R2, and R3, respectively, and Z2 is the impedance of the low-impedance portions of R1, R2, and R3. f 0 is the resonant frequency, c is the speed of light, and λ is the velocity of light. g Waveguide wavelength It is the effective dielectric constant.