Filtering grid array antenna based on high-resistance silicon substrate
By integrating a filter grid array antenna with multiple filtering mechanisms on a high-resistivity silicon substrate, the problems of insufficient frequency selectivity and anti-interference capability of millimeter-wave antennas are solved, achieving high-performance antenna packaging integration and reducing system loss and complexity.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HARBIN INSTITUTE OF TECHNOLOGY (SHENZHEN) (INSTITUTE OF SCIENCE AND TECHNOLOGY INNOVATION HARBIN INSTITUTE OF TECHNOLOGY SHENZHEN)
- Filing Date
- 2026-01-05
- Publication Date
- 2026-04-21
AI Technical Summary
Existing millimeter-wave antenna-in-package (AiP) technology suffers from insufficient frequency selectivity and interference immunity, leading to a decline in system performance and an increase in package size and cost. Meanwhile, discrete filters introduce additional losses and complexity.
Design a filter grid array antenna based on a high-resistivity silicon substrate. By integrating a high-frequency radiation filter unit, a low-frequency energy trap filter unit, and a low-frequency conduction filter unit into the antenna structure, and combining multiple filtering mechanisms, multiple controllable filter zeros are achieved to suppress out-of-band interference.
Without increasing antenna size, multiple controllable filter zeros were achieved across a wide frequency band, improving out-of-band rejection capability and passband roll-off characteristics, and enhancing anti-interference capability and overall performance.
Smart Images
Figure CN121906119A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of millimeter-wave antenna technology, and in particular to a filter grid array antenna based on a high-resistivity silicon substrate. Background Technology
[0002] With the rapid development of wireless communication and sensing technologies, the application of millimeter-wave bands (such as 77GHz) is becoming increasingly widespread, especially in cutting-edge fields such as advanced automotive radar, 5G / 6G communication, and industrial automation. To meet the stringent requirements of these applications for miniaturization, low cost, and high performance, antenna-in-package (AiP) technology, which integrates the antenna with the RF integrated circuit, has become the mainstream development direction. By employing advanced semiconductor processes such as high-resistivity silicon, the AiP solution can significantly shorten the interconnection path between the chip and the antenna, thereby reducing transmission loss, system size, and manufacturing costs.
[0003] However, existing conventional AiP technologies still face significant technical challenges in practical applications. On one hand, to achieve complete RF front-end functionality, a complete system, in addition to the antenna and chip, must include a bandpass filter for suppressing out-of-band interference. In traditional AiP designs, this filter is typically placed as a discrete, independent component on the system motherboard outside the package module. This design not only contradicts the original intention of AiP technology to pursue ultimate integration, increasing additional package size, wiring complexity, and cost, but the insertion loss introduced by this discrete filter itself also directly degrades the noise figure and energy efficiency of the entire RF link.
[0004] On the other hand, as millimeter-wave spectrum resources become increasingly congested, devices will operate in extremely complex electromagnetic environments, and interference signals from other communication systems or radars will become increasingly severe. Traditional AiP antennas, due to their lack of effective frequency selectivity, have poor anti-interference capabilities (electromagnetic compatibility, EMC) and are easily affected by out-of-band signals, leading to performance degradation or even system failure. This is unacceptable in applications such as automotive radar, where safety requirements are extremely high.
[0005] While there are existing improvements to millimeter-wave antennas, these improvements still suffer from the following technical shortcomings: (1) The lack of frequency selectivity in antenna-integrated packaging (AiP) technology results in insufficient anti-interference capability.
[0006] Existing AiP solutions mainly focus on the integration of antennas and chips, but the antenna itself, as a broadband receiver, is sensitive to out-of-band interference signals, and its reliability faces severe challenges in increasingly complex electromagnetic environments.
[0007] (2) Adding a separate bandpass filter will increase the package size.
[0008] Traditional solutions to out-of-band electromagnetic interference require adding a separate bandpass filter outside the packaged module. This not only increases the system size, design complexity, and manufacturing cost, but also introduces additional assembly steps.
[0009] (3) Discrete filters and interconnect losses degrade the overall performance of the RF link.
[0010] The insertion loss inherent in external discrete filters and their connecting traces directly reduces the signal-to-noise ratio of the receiving link (degrades the noise figure) and reduces the output power of the transmitting link, thereby limiting the radar's detection range or the coverage of the communication system.
[0011] Therefore, there is an urgent need for a new type of millimeter-wave antenna solution that can maintain all the integrated advantages of AiP technology, fundamentally solve the system's requirements for frequency selectivity and anti-interference capability, and avoid the additional losses and complexity caused by introducing discrete filters. Summary of the Invention
[0012] This invention provides a filter grid array antenna based on a high-resistivity silicon substrate, aiming to solve the technical problems existing in the improvement scheme of millimeter-wave antennas.
[0013] This invention provides a filtered grid array antenna based on a high-resistivity silicon substrate, comprising a first metal layer, a second metal layer, a third metal layer, and a dielectric layer. The third metal layer, dielectric layer, second metal layer, and first metal layer are arranged sequentially to form a stacked structure. The third metal layer has a main radiator, the second metal layer has an antenna ground, and the first metal layer has a microstrip feed strip. The main radiator includes a grid array antenna structure, a high-frequency radiating filter unit, and a low-frequency energy trapping filter unit. The high-frequency radiating filter unit and the low-frequency energy trapping filter unit are arranged in the region of the grid array antenna structure. The antenna ground has a resonant slot, and the microstrip feed strip has a low-frequency conducting filter unit. The microstrip feed strip is fed so that electromagnetic energy is coupled into the grid array antenna structure through the resonant slot.
[0014] As a further improvement of the present invention, the grid array antenna structure is composed of multiple vertical metal strips and multiple horizontal metal strips, wherein the vertical metal strips are set to a length of half a dielectric wavelength and the horizontal metal strips are set to a length of one dielectric wavelength.
[0015] As a further improvement of the present invention, the high-frequency radiation-type filter unit includes convex parasitic resonant patches, and a pair of convex parasitic resonant patches are symmetrically arranged on the upper and lower sides of the grid array antenna structure.
[0016] As a further improvement of the present invention, the low-frequency energy trapping filter unit includes a U-shaped metal resonant strip, which is symmetrically arranged in the central region of the grid array antenna structure, and the U-shaped metal resonant strip is placed directly above the resonant slot.
[0017] As a further improvement of the present invention, the low-frequency conductive filter unit includes a short-circuit stub resonator, which is composed of a transverse metal strip near the resonant gap and a short-circuit via. The transverse metal strip is parallel to the resonant gap and is connected to the ground through the short-circuit via.
[0018] As a further improvement of the present invention, the filter grid array antenna based on a high-resistivity silicon substrate also includes a passivation layer, wherein the passivation layer is surrounded on both the upper and lower surfaces of the first metal layer and the second metal layer.
[0019] As a further improvement of the present invention, the dielectric layer includes a high-resistivity silicon dielectric and a silicon dioxide layer, wherein the silicon dioxide layer surrounds the upper and lower surfaces of the high-resistivity silicon dielectric.
[0020] As a further improvement of the present invention, the first metal layer is provided with a power feed disk, which is located on one side of the low-frequency conductive filter unit.
[0021] The beneficial effects of this invention are: by combining multiple filtering mechanisms, without significantly increasing the antenna size, this invention achieves the ability to generate multiple controllable filtering zeros in a wide frequency band, thereby obtaining a wider suppression bandwidth, deeper out-of-band suppression, and steeper passband roll-off characteristics than a single filtering method, solving the problem of the difficulty in deeply integrating high-performance antennas and complex filtering functions in the prior art. Attached Figure Description
[0022] Figure 1 This is an overall structural diagram of the filter grid array antenna based on a high-resistivity silicon substrate according to the present invention; Figure 2 This is a diagram of the high-resistivity silicon dielectric stack structure in this invention; Figure 3 This is a top view of the structure of the filter grid array antenna based on a high-resistivity silicon substrate according to the present invention; Figure 4 This is a diagram of the feeding structure of the filter grid array antenna based on a high-resistivity silicon substrate according to the present invention; Figure 5 This is the S11 curve of the filter grid array antenna based on a high-resistivity silicon substrate of the present invention. Figure 6 This is the actual gain-frequency curve of the antenna line of the filter grid array antenna based on a high-resistivity silicon substrate according to the present invention; Figure 7This is the E-plane radiation pattern of the filter grid array antenna based on a high-resistivity silicon substrate according to the present invention; Figure 8 This is the H-plane radiation pattern of the filter grid array antenna based on a high-resistivity silicon substrate according to the present invention; Figure 9 This is a radiation efficiency diagram of the filter grid array antenna based on a high-resistivity silicon substrate according to the present invention. Detailed Implementation
[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.
[0024] In the critical 77 GHz millimeter-wave band, advanced automotive radar and industrial high-precision sensing are facing increasingly severe challenges: on the one hand, systems need to be miniaturized and cost-effective to adapt to large-scale deployment; on the other hand, the increasingly complex electromagnetic environment requires sensors to have extremely strong anti-interference capabilities to ensure the reliability and security of data transmission. This invention successfully achieves an antenna-in-package (AiP) solution by integrating filtering functionality into the grid array antenna (GAA) structure and employing a high-resistivity silicon packaging process. This solution not only provides high-performance radiation but also suppresses out-of-band interference at the physical layer, while seamlessly integrating with chips, thus perfectly meeting the core requirements of compactness, low cost, and high reliability in the aforementioned application areas.
[0025] Specifically, such as Figures 1 to 4 As shown, a filter grid array antenna based on a high-resistivity silicon substrate according to the present invention includes a first metal layer 1, a second metal layer 2, a third metal layer 3, and a dielectric layer 4. The third metal layer 3, dielectric layer 4, second metal layer 2, and first metal layer 1 are arranged sequentially to form a stacked structure. The third metal layer 3 is provided with a main radiator 5, the second metal layer 2 is provided with an antenna ground 6, and the first metal layer 1 is provided with a microstrip feed bar 7. The main radiator 5 includes a grid array antenna structure 51, a high-frequency radiating filter unit, and a low-frequency energy trapping filter unit. The high-frequency radiating filter unit and the low-frequency energy trapping filter unit are arranged in the region of the grid array antenna structure 51. The antenna ground 6 is provided with a resonant slot 61. The microstrip feed bar 7 is provided with a low-frequency conducting filter unit. The microstrip feed bar 7 is fed so that electromagnetic energy is coupled into the grid array antenna structure 51 through the resonant slot 61.
[0026] The antenna designed in this invention is integrated in a multilayer structure using high-resistivity silicon packaging technology. Its core functional units are distributed across different metal layers, working together to achieve filtering and radiation functions. Figure 1 The stacked structure of the high-resistivity silicon packaging process is shown.
[0027] The main radiator 5, composed of grating array antenna radiating elements, is located in the third metal layer 3 (M3), the antenna ground 6 is located in the second metal layer 2 (M2), and the microstrip feed bar 7 structure is located in the first metal layer 1 (M1). The entire metal plate of the second metal layer 2 serves as the ground plane. A rectangular slot resonating within the target frequency band is designed in the middle of the second metal layer 2 ground plane to feed the microstrip feed bar 7 structure of the first metal layer 1. Electromagnetic energy is coupled from the first metal layer 1 to the grating array antenna in the third metal layer 3 through the resonant slot 61. The energy resonates within the antenna structure of the third metal layer 3 and is converted into electromagnetic energy, radiating into free space.
[0028] The grid array antenna structure 51 is composed of multiple vertical metal strips 52 and multiple horizontal metal strips 53. The vertical metal strips 52 are set to a length of half a dielectric wavelength, and the horizontal metal strips 53 are set to a length of one dielectric wavelength.
[0029] like Figure 3 As shown, the main radiator 5 (M3 layer): The core of the antenna is a grid array antenna structure 51, which serves as the main radiator 5 and is responsible for achieving efficient radiation within the target operating frequency band (76~81 GHz). The longitudinal metal strips 52 are set to half the length of the dielectric wavelength at 78 GHz, serving as resonators and radiators. The transverse metal strips 53 are set to the length of a dielectric wavelength, serving to transmit electromagnetic energy between the longitudinal metal strips 52. The length of a dielectric wavelength allows each longitudinal metal strip 52 to be excited in phase, resulting in higher gain in the far field.
[0030] The high-frequency radiating filter unit includes convex parasitic resonant patches 54, and a pair of convex parasitic resonant patches 54 are symmetrically arranged on the upper and lower sides of the grid array antenna structure 51. For example... Figure 3 As shown, the grid array antenna structure 51 in this embodiment can be composed of seven longitudinal metal strips 52 forming the radiating part. A pair of convex parasitic resonant patches 54 are symmetrically arranged on the upper and lower sides of the radiating part as high-frequency radiating filter units of the main radiator 5.
[0031] Type 1 Filtering Unit / High-Frequency Radiation Filter (M3 Layer): Four convex parasitic resonant patches 54 are symmetrically arranged on the upper and lower sides of the GAA unit. These parasitic patches will sense the magnetic field energy around the GAA unit and generate a reverse radiation current at high frequency, which is used to generate a radiation null on the high-frequency side of the antenna operating frequency band.
[0032] The low-frequency energy trapping filter unit includes a U-shaped metal resonant strip 55, which is symmetrically arranged in the central region of the grid array antenna structure 51, and is positioned directly above the resonant slot 61. Figure 3As shown, in the four grid structures used in this embodiment, each grid of the middle double grid structure is arranged with a U-shaped metal resonant strip 55, and the two U-shaped metal resonant strips 55 are stacked together as low-frequency energy trapping filter units of the main radiator 5.
[0033] Type II Filtering Unit / Low-Frequency Energy Trapping Filter (M3 Layer): Two U-shaped metal resonant strips 55 are symmetrically arranged in the central region of the GAA unit and precisely placed directly above the bottom feed slot to generate the first set of low-frequency radiation nulls on the low-frequency side of the antenna's operating frequency band.
[0034] The low-frequency conductive filter unit includes a short-circuit stub resonator 71, which is composed of a transverse metal strip 72 near the resonant gap 61 and a short-circuit via 73. The transverse metal strip 72 is parallel to the resonant gap 61, and the metal strip is connected to the ground through the short-circuit via 73.
[0035] Third type of filter unit / low-frequency conductive filter (M1 layer): such as Figure 4 As shown, a short-circuit stub resonator 71 is integrated in the feed network of layer M1. The short-circuit stub resonator 71 consists of a transverse metal strip 72 near the coupling gap and a short-circuit via 73 (Via) connecting it to the ground plane, for generating a second set of depth-controllable radiation nulls on the low-frequency side.
[0036] Electromagnetic energy travels along the transverse metal strip 72, and when it reaches the vicinity of the resonant slot 61, it couples into the resonant slot 61, and then transfers the energy upwards to the antenna of the upper M3 metal layer. The short-circuit via 73 connects the feed structure of the first metal layer 1 and the antenna ground 6 of the second metal layer 2. The short-circuit via 73 is equivalent to passing through the passivation layer between the M1 and M2 layers.
[0037] The filter grid array antenna based on a high-resistivity silicon substrate also includes a passivation layer. The first metal layer 1 and the second metal layer 2 are surrounded by passivation layers on both the top and bottom. The first metal layer 1 and the third metal layer 3 are surrounded by polyimide layers on the top and bottom. This layer serves as a passivation layer, protecting the antenna metal layers and preventing metal oxidation.
[0038] Dielectric layer 4 includes a high-resistivity silicon dielectric and a silicon dioxide layer, with the high-resistivity silicon dielectric surrounded by silicon dioxide layers on both its top and bottom surfaces. The intermediate dielectric consists of a 200 μm thick high-resistivity silicon dielectric and silicon dioxide layers above and below it.
[0039] High-resistivity silicon dielectric is the core of the entire process. RF circuit chips are suitable for silicon-based processes, and high-resistivity silicon can suppress substrate loss and eddy currents, improve isolation, reduce crosstalk, and reduce nonlinear harmonic distortion. RF chips are susceptible to electromagnetic interference, which can be reduced in high-resistivity silicon dielectric. Designing antennas in high-resistivity silicon processes allows for easy integration with RF chips designed in high-resistivity silicon. The silicon dioxide layer, as an oxide layer, reduces parasitic capacitance; provides DC isolation and leakage protection, thus protecting and improving performance.
[0040] The first metal layer 1 is equipped with a feed disk 8, which is located on one side of the low-frequency conductive filter unit. The feed disk 8 serves as a grounding structure and is a feed structure for a GSG, facilitating subsequent antenna fabrication and testing.
[0041] This invention achieves multi-level, multi-point out-of-band suppression by combining radial filtering with two different conductive filtering mechanisms. The overall antenna structure is as follows: Figure 1 As shown. The high-resistivity silicon process has a multi-layered structure; this 3D diagram only shows the metal layer and the intermediate high-resistivity silicon dielectric layer 4 as a three-dimensional representation. The specific antenna implementation mechanism is as follows: (1) In-band radiation mechanism (dominated by GAA): Within the target operating frequency band, energy is efficiently generated from the feed line through the coupling slot to excite the GAA unit, forming a stable high-gain directional beam.
[0042] (2) High-frequency filtering mechanism (dominated by convex parasitic patch - radiation destructive): This mechanism is a radiation-type filter. Within the high-frequency stopband, a specific magnetic coupling and inductive response are formed between the convex parasitic patch and the main radiating unit of the GAA, resulting in a phase difference of approximately 180° between their induced currents. This causes their electromagnetic waves radiated in the far field to cancel each other out, thus creating a high-frequency radiation null.
[0043] (3) First low-frequency filtering mechanism (dominated by U-shaped resonant strip - energy trapping): This mechanism is an energy trapping filter on the conduction path. At the first preset low-frequency null, the U-shaped strip covering the feed gap is strongly excited and enters a resonant state. Its powerful resonant current "captures" and consumes most of the energy coupled through the gap in the test pattern, thereby blocking the energy transmission path to the main radiating unit of the GAA and forming a low-frequency radiation null. The U-shaped strip itself is in a non-radiative mode, and the currents of the upper and lower strips are reversed when they resonate, ensuring low cross-polarization and filtering effect.
[0044] (4) Second low-frequency filtering mechanism (dominated by short circuit - energy diversion): This mechanism is a circuit-level filter in the feed network, based on the principle of resonant energy shunting. A short-circuit resonator, consisting of a transverse metal strip 72 and a short-circuit via 73, is connected in parallel immediately adjacent to the coupling gap on the main feed line. This resonator is designed to resonate at a preset low-frequency zero-point. According to transmission line theory, it exhibits extremely low input impedance (approximately short-circuited) at the feed line connection point. The signal energy at this frequency is effectively shunted to ground via this low-impedance path, rather than continuing to propagate to the coupling gap, thus creating a transmission zero in the feed network, preventing the radiation of energy at this frequency, and achieving deep low-frequency suppression.
[0045] The performance of the filter grid array antenna based on a high-resistivity silicon substrate is as follows: The impedance bandwidth covers 76.02 - 81.56 GHz, with the deepest point of S11 reaching -31.8 dB, such as... Figure 5 As shown.
[0046] The highest actual gain is 6.21 dBi, with in-band gain ripple less than 0.4 dB. The deepest zero-point gain at low frequencies is -21.8 dBi, and the deepest zero-point gain at high frequencies is -30.5 dBi. Figure 6 As shown.
[0047] The antenna radiation patterns in the E and H planes at 77 GHz are as follows: Figure 7 , Figure 8 As shown, the antenna successfully achieved wide-beam side-firing performance, with cross-polarized radiation levels in both the E-plane and H-plane below -38 dB and a radiation-before-after ratio greater than 20 dB.
[0048] Antenna radiation efficiency such as Figure 9 As shown, the designed antenna achieves a maximum radiation efficiency of 61.84% at 78 GHz, indicating that the designed antenna can still maintain excellent radiation performance even when integrated into a high-resistivity silicon dielectric with high dielectric loss and high ohmic loss.
[0049] The performance of this antenna is shown in the table below:
[0050] In the field of millimeter-wave antenna technology, lattice array antennas have become the preferred solution for achieving high-performance radiation due to their higher radiation efficiency, higher gain, and effective suppression of surface waves compared to traditional microstrip antennas. Meanwhile, filtering antennas, by integrating frequency selection and antenna radiation functions, can effectively replace discrete bandpass filters in the RF front-end, thereby significantly reducing system size, lowering insertion loss, and enhancing the suppression of out-of-band signals.
[0051] This invention combines and further enhances the advantages of the aforementioned technologies, designing a novel millimeter-wave filtered grating array antenna and its integrated packaging structure employing a comprehensive filtering mechanism. The design uses a high-performance grating array antenna as the main radiator 5, and strategically integrates parasitic resonant coupling units in its electromagnetic near field to generate first-type filter nulls through far-field destructive interference of the radiation modes. Secondly, this invention also integrates resonant stubs and other structures along the antenna's feed network path to generate second-type filter nulls at different frequencies through circuit-level reflection of the conduction modes. Finally, this invention sets a resonant C-ring structure above the coupling gap, resonating at the desired frequency null, consuming energy, and generating a third-type null.
[0052] By combining multiple filtering mechanisms, this invention achieves the ability to generate multiple controllable filter zeros over a wide frequency band without significantly increasing the antenna size. This results in a wider suppression bandwidth, deeper out-of-band suppression, and steeper passband roll-off characteristics compared to a single filtering method, solving the problem of deep integration between high-performance antennas and complex filtering functions in existing technologies.
[0053] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.
Claims
1. A filter grid array antenna based on a high-resistivity silicon substrate, characterized in that, The antenna comprises a first metal layer, a second metal layer, a third metal layer, and a dielectric layer. The third metal layer, dielectric layer, second metal layer, and first metal layer are arranged sequentially to form a stacked structure. The third metal layer has a main radiator, the second metal layer has an antenna ground, and the first metal layer has a microstrip feed strip. The main radiator includes a grid array antenna structure, a high-frequency radiating filter unit, and a low-frequency energy trapping filter unit. The high-frequency radiating filter unit and the low-frequency energy trapping filter unit are arranged in the area of the grid array antenna structure. The antenna ground has a resonant slot, and the microstrip feed strip has a low-frequency conducting filter unit. The microstrip feed strip is fed so that electromagnetic energy is coupled into the grid array antenna structure through the resonant slot.
2. The filter grid array antenna based on a high-resistivity silicon substrate according to claim 1, characterized in that, The grid array antenna structure consists of multiple vertical metal strips and multiple horizontal metal strips. The vertical metal strips are set to a length of half a dielectric wavelength, and the horizontal metal strips are set to a length of one dielectric wavelength.
3. The filter grid array antenna based on a high-resistivity silicon substrate according to claim 1, characterized in that, The high-frequency radiating filter unit includes convex parasitic resonant patches, and a pair of convex parasitic resonant patches are symmetrically arranged on the upper and lower sides of the grid array antenna structure.
4. The filter grid array antenna based on a high-resistivity silicon substrate according to claim 1, characterized in that, The low-frequency energy trapping filter unit includes a U-shaped metal resonant strip, which is symmetrically arranged in the central region of the grid array antenna structure and placed directly above the resonant slot.
5. The filter grid array antenna based on a high-resistivity silicon substrate according to claim 1, characterized in that, The low-frequency conductive filter unit includes a short-circuit stub resonator, which is composed of a transverse metal strip near the resonant gap and a short-circuit via. The transverse metal strip is parallel to the resonant gap and is connected to the ground through the short-circuit via.
6. The filter grid array antenna based on a high-resistivity silicon substrate according to claim 1, characterized in that, It also includes a passivation layer, with the first metal layer and the second metal layer both surrounded by a passivation layer on their upper and lower surfaces.
7. The filter grid array antenna based on a high-resistivity silicon substrate according to claim 1, characterized in that, The dielectric layer includes a high-resistivity silicon dielectric and a silicon dioxide layer, with the silicon dioxide layer surrounding both the upper and lower surfaces of the high-resistivity silicon dielectric.
8. The filter grid array antenna based on a high-resistivity silicon substrate according to claim 1, characterized in that, The first metal layer is provided with a power feed disk, which is located on one side of the low-frequency conductive filter unit.