Antenna array with independent RFIC chip and antenna element lattice geometries

Abstract

To provide an antenna apparatus with distributed RFIC chips in which, since I / O pads of RFICs are aligned with feed points of antenna elements, transmission lines and / or additional redistribution layers between first and second layers may be avoided, allowing a compact, low-loss design.SOLUTION: An antenna apparatus includes a first component layer having a plurality of RFICs 110 arranged in a first lattice geometry (e.g., rectangular), where each RFIC comprises beamforming circuitry. A second, parallel component layer overlays the first component layer and includes a plurality of antenna elements 120 arranged in a second, different lattice geometry (e.g., triangular). The antenna elements have respective feed points 122 each coupled to an input / output (I / O) pad of an RFIC. Each I / O pad is aligned with the feed point coupled to the I / O pad along an axis orthogonal to the first and second layers.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] (Related Applications) This patent application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 011,056, filed April 16, 2020, entitled "Antenna Array with Independent RFIC Chip and Antenna Element Lattice Geometry," the entirety of which is incorporated herein by reference.

[0002] FIELD OF THE INVENTION The present disclosure relates generally to antenna arrays with distributed RFIC chips. [Background technology]

[0003] Related Technology Considerations Antenna arrays are currently used in a variety of applications at microwave and millimeter-wave frequencies, such as in aircraft, satellites, vehicles, and base stations for general terrestrial communications. Such antenna arrays typically include microstrip radiating elements driven with phase-shifting beamforming circuits to form a phased array for steering a beam. It is often desirable for the entire antenna system, including the antenna array and beamforming circuits, to occupy minimal space with a low profile while meeting required performance metrics.

[0004] An "embedded" antenna array may be defined as an antenna array constructed with antenna elements integrated with a radio frequency integrated circuit chip (RFIC) in a compact structure. An embedded array can have a sandwich-type configuration in which the antenna elements are located in an external component layer and the RFIC (radio frequency integrated circuit chip) is distributed across the effective antenna aperture in an adjacent, parallel component layer behind the antenna element layer. The RFIC may include a power amplifier (PA) for transmission, a low noise amplifier (LNA) for reception, and / or a phase shifter for beam steering. By distributing the PA (power amplifier) ​​and LNA (low noise amplifier) ​​in this manner, higher efficiency during transmission and improved noise performance during reception can be achieved. The reliability of the antenna array can also be improved because overall antenna performance is still acceptable even if a small number of amplifiers malfunction. The RFIC typically includes other beamforming circuitry such as filters, impedance matching elements, RF couplers, transmit / receive (T / R) switches, and control lines. Summary of the Invention

[0005] In one aspect of the present disclosure, an antenna apparatus includes a first component layer including a plurality of RFICs arranged in a first plane having a first grid arrangement, each RFIC including a beamforming circuit. A second component layer is overlaid on the first component layer and includes a plurality of antenna elements arranged in a second plane parallel to the first plane and with a second, different grid arrangement. Each antenna element has a respective feed point connected to an input / output (I / O) pad of the RFIC. The I / O pads are aligned with the feed points connected to the I / O pads along an axis orthogonal to the first and second planes.

[0006] The first grid arrangement may be rectangular and the second grid arrangement may be triangular.

[0007] Because the I / O pads of the RFIC are aligned with the feed points of the antenna elements, transmission lines and / or additional redistribution layers between the first and second layers can be avoided, enabling a compact and low-loss design. [Brief explanation of the drawings]

[0008] The above and other aspects and features of the disclosed technology will become more apparent from the following detailed description, taken in conjunction with the accompanying drawings, in which like reference numerals indicate like elements or features. Various elements of the same or similar type may be distinguished by appending a dash to the reference label and a second label that distinguishes between the same / similar elements (e.g., -1, -2), or by appending the second label directly to the reference label. However, if a given description uses only a first reference label, it is applicable to any one of the same / similar elements having the same first reference label, regardless of the second label. Elements and features may not be drawn to scale in the drawings. [Figure 1] FIG. 1 is a plan view of an exemplary antenna apparatus according to one embodiment. [Figure 2] 2 is a diagram showing an example of a lattice arrangement of antenna elements and RFICs in the antenna device of FIG. 1. [Figure 3] 3 is a cross-sectional view of a portion of the antenna device taken along line 3-3 in FIG. 1. [Figure 4A] 1 is a cross-sectional view showing an example of a connection structure between an antenna element and an RFIC in an antenna device. [Figure 4B] FIG. 4B is a cross-sectional view taken along line 4B-4B of FIG. 4A, illustrating the ground-signal-ground connection configuration. [Figure 5] 10 is a cross-sectional view showing another example of a connection structure between an antenna element and an RFIC in an antenna device. FIG. [Figure 6] 1 is a cross-sectional view of an exemplary flip-chip connection between an antenna element and an RFIC in an antenna device. [Figure 7A] 1 is a cross-sectional view of an exemplary dual-via type connection between an antenna element and an RFIC in an antenna apparatus. [Figure 7B]7B is a cross-sectional view of an exemplary portion of an antenna device illustrating an exemplary extended connection structure that includes the dual via type connection of FIG. 7A. [Figure 8A] Illustrated are examples of placement of antenna feed locations relative to the connected RFIC. [Figure 8B] Illustrated are examples of placement of antenna feed locations relative to the connected RFIC. [Figure 8C] Illustrated are examples of placement of antenna feed locations relative to the connected RFIC. [Figure 9] FIG. 8C illustrates an example layout of beamforming circuitry within an RFIC with I / O pads arranged according to the arrangement of FIG. 8B. DETAILED DESCRIPTION OF THE INVENTION

[0009] The following description, with reference to the accompanying drawings, is provided for illustrative purposes to assist in a comprehensive understanding of certain exemplary embodiments of the technology disclosed herein. Although this specification includes various specific details to assist those skilled in the art in understanding the technology, these details should be considered as merely exemplary. For the sake of brevity and clarity, the description of well-known functions and structures may be omitted if it may obscure the understanding of the technology by those skilled in the art.

[0010] FIG. 1 is a top view of an exemplary antenna device 100 according to one embodiment. The antenna device 100 may be constructed of a thin laminate structure having an upper component layer including a plurality of antenna elements 120 forming an antenna array in a first plane and a lower component layer including a plurality of radio frequency integrated circuit chips (RFICs) 110 disposed in a second plane parallel to the first plane and connected to the antenna elements 120. A substrate 150 may be disposed between the upper and lower component layers. A ground plane (not shown) may be printed on the underside of the substrate 150 to reflect signal energy to and from the antenna elements 120. Due to such a multi-layer structure with integrated antenna elements 120 and RFICs 110, the antenna device 100 may be referred to as an embedded antenna array. In the following description, for convenience of explanation, horizontal planes / directions generally refer to planes / directions parallel to the major surfaces of the antenna device 100, and vertical directions refer to the orthogonal direction, i.e., the thickness direction of the antenna device 100.

[0011] Each antenna element 120 may be a microstrip patch antenna element printed on the substrate 150 and electrically or electromagnetically coupled (“fed”) to the RFIC 110 at a respective feed point 122. The RFIC 110 may be mechanically connected to the substrate 150, such as by solder bump connections to a ground plane and other connection pads located on the substrate 150. Each RFIC 110 may include transmit and / or receive RF front-end circuitry including amplifiers, phase shifters, and filters. (Herein, RF front-end circuitry may be referred to interchangeably as “beamforming” circuitry.) With RF front-end amplifiers distributed across the antenna array in this manner, the antenna device 100 may be referred to as an active antenna array. In some embodiments, each RFIC 110 includes receive circuitry comprising at least one low-noise amplifier (LNA) for amplifying receive signals and at least one power amplifier (PA) for amplifying transmit signals. If the antenna apparatus 100 is designed as a phased array, each RFIC 110 may include at least one dynamically controllable phase shifter for steering the receive and / or transmit beams.

[0012] In one embodiment, the antenna device 100 is configured for operation over the millimeter (mm) wave frequency band, commonly defined as the band in the 30 GHz to 300 GHz range. In other examples, the antenna device 100 operates in the microwave range of approximately 1 GHz to 30 GHz, or in the sub-microwave range below 1 GHz. As used herein, radio frequency (RF) signals refer to signals having frequencies between 1 GHz and below 300 GHz. It should be noted that RFICs configured to operate at microwave or mm-wave frequencies are often referred to as monolithic microwave integrated circuits (MMICs) and are typically fabricated from III-V semiconductor materials.

[0013] When implemented as microstrip patches, the antenna elements 120 can have any suitable shape, such as square, rectangular, circular, elliptical, or variations thereof, and can be provided and configured in a manner sufficient to achieve a desired polarization, e.g., circular, linear, or elliptical. The number of antenna elements 120, their type, size, shape, inter-element spacing, and the manner in which they are provided may be varied by design to achieve targeted performance metrics. While FIG. 1 shows an example with 64 antenna elements 120, in typical embodiments, the antenna device 100 includes hundreds or thousands of antenna elements 120. In the embodiments described below, each antenna element 120 is a microstrip patch provided with a probe feed. The probe feed may be implemented as a through-substrate via (TSV) (“via”) that electrically connects to an input / output (I / O) pad on the RFIC 110. The I / O pad is an interface that allows signals to enter and exit the RFIC 110. In other examples, an electromagnetic feed mechanism is used instead of vias, and each antenna element 120 is excited by near-field energy from its respective feed point.

[0014] In the antenna apparatus 100, the RFICs 110 are arranged in a first grid arrangement, and the antenna elements 120 are arranged in a second (different) grid arrangement. In FIG. 1 and other examples herein, the first grid arrangement is rectangular (as used herein, "square" is a subset of "rectangle") and the second grid arrangement is non-rectangular, e.g., triangular, although other combinations are possible in other embodiments. A non-rectangular antenna array grid arrangement (e.g., triangular) can provide desirable performance advantages compared to a rectangular grid, such as allowing wider spacing of the antenna elements 120 with grating lobe-free performance. Mutual coupling between the antenna elements 120 can also be beneficially reduced in a triangular grid compared to a rectangular grid configuration.

[0015] In either case, the RFICs 110 and antenna elements 120 are arranged in different respective grid configurations, but each feed point 122 is vertically aligned with the corresponding I / O pad of the RFIC 110 connected to that feed point. For example, the area of ​​each feed point 122 in FIG. 1 is represented as an "o," with the "x" within each "o" representing the connected RFIC 110 I / O pad. Thus, in the vertical direction, the feed points 122 overlap the I / O pads. In other words, the I / O pads of the various RFICs 110 arranged in a horizontal plane define a pattern that matches that of the feed points 122. This matching configuration reduces the distance between each feed point 122 and the corresponding I / O pad, eliminating the need for lossy transmission lines that traverse horizontally between them. Conventionally, these transmission lines are formed in the multi-layer connection between the RFIC 110 and the antenna substrate 150. This is in part because the I / O pads on standard RFICs are symmetrically located adjacent to opposite edges of their rectangular footprints. The present embodiments allow for the elimination of such multi-layer connections and the reduction / elimination of losses otherwise caused by such transmission lines.

[0016] In FIG. 1 , the positions of the feed points 122 and I / O pads of the RFICs 110 are shown vertically aligned. As used herein, “alignment” between the feed points and the connected I / O pads can be either precise alignment (within manufacturing tolerances) or “substantial alignment” (discussed below) with a slight offset built in for manufacturing purposes. FIG. 1 also shows each RFIC 110 connected to four antenna elements 120. In other embodiments, each RFIC 110 is connected to more or fewer antenna elements 120. Note also that in some embodiments, each of the antenna elements 120 is shared for transmit and receive operations, with each RFIC 110 including appropriate transmit / receive (T / R) circuitry therein to separate signals in the transmit and receive paths. However, in other antenna systems, two separate antenna arrays 100 are used, one for transmit and one for receive. In this case, all antenna elements 120 of a given antenna array 100 are either "receive antenna elements" dedicated to receive operation, or "transmit antenna elements" dedicated to transmit operation.

[0017] Each grid arrangement can be defined by a center point 123 of the antenna elements 120 and a center point 113 of the RFICs 110. (Note that the feed points 122 may be offset from the center points 123 of the antenna elements 120.) Referring to FIG. 2 , imaginary lines connecting the center points 123 form a triangular grid 202 of the antenna elements 120. Imaginary lines connecting the center points 113 of the RFICs 110 form a rectangular or square grid 204 of the RFICs 110. As seen in FIG. 1 , for four antenna elements 120 connected to one respective RFIC 110 in such a grid arrangement, for any given RFIC 110, two I / O pads (x's in the feed points 122) are located on opposite edges of the RFIC, and the other two I / O pads are located inward from opposite edges. In general, when each RFIC 110 in a rectangular grid is connected to at least two antenna elements 120 in a non-rectangular grid, some of the RFIC I / O pads may be located on opposing edges of the RFIC 110, with the remaining I / O pads located inward from these opposing edges. This I / O pad arrangement differs from standard RFICs (with rectangular footprints), which typically have all their I / O pads located close to opposing edges (including the “G” ports of a ground-signal-ground (“GSG”) or ground-signal (“GS”) connection set, as described below). As a result, when a standard RFIC is arranged in a rectangular grid and connected to antenna elements in a non-rectangular grid, some or all of the feed point locations will not be aligned with the I / O pad locations. This complicates the design by requiring horizontal transmission lines, making interconnections between the RFIC and the antenna elements difficult and lossy. The present embodiment, using aligned feed points and I / O pads, avoids such complexity and transmission line losses.

[0018] 3 is a simplified cross-sectional view of a portion of the antenna apparatus 100, showing an example structure along two adjacent RFICs 110 of FIG. 1. A plurality of vias 302 are formed in the substrate 150, each connecting the feed point 122 of an antenna element 120 to an RFIC 110 I / O pad (not shown in FIG. 3) at an I / O pad location 315. Hereinafter, the I / O pad location 315 is assumed to be the center location of the I / O pad. Detailed examples of I / O pads are described below.

[0019] The ground plane 340 may be printed on the underside of the substrate 150. Because the feed point 122 locations and the corresponding I / O pad locations 315 are vertically aligned, one or more redistribution layers with horizontally oriented transmission lines between the RFIC 110 and the substrate 150 can be avoided. Therefore, the RFIC 110 may be directly attached to the connection points on the substrate 150 and the ground plane 340. Furthermore, the alignment of the I / O pad locations 315 and the corresponding feed point locations 122 reduces the complexity of the antenna substrate 150 (including the number of required substrate layers). Note that the number of dielectric and conductive layers in the antenna substrate 150 may vary depending on the embodiment. It is further noted that in some embodiments, each antenna element 120 may have two feed points that connect to two respective I / O pads on the RFIC 110 through two vias 302 to form circular polarization in some designs. However, the antenna element 120 designs described below utilize a single feed to achieve circular polarization. Additionally, if a GSG connection is made, the ground pads of RFIC 110 may be connected to ground plane 340 at locations 317 on both sides of via 302. Alternatively, a GSG connection is used in which a single ground pad to ground plane 340 connection is made on only one side of via 302.

[0020] 4A is a cross-sectional view of an exemplary connection structure 400 between one antenna element 120 and the RFIC 110 in the antenna apparatus 100. In this embodiment, “precise” vertical alignment of the feed point 122 and the touch pad location 315 is targeted by design through a connection via 302. (Due to manufacturing tolerances discussed below, a predetermined range of horizontal offset may be allocated even for this “precise alignment.”) The via 302 electrically contacts the antenna element 120 at the feed point 122 and passes through the antenna substrate 150 to connect the antenna element 120 to a catch pad 406 on the bottom surface 453 of the substrate 150. The feed point 122 is the center of the electromagnetic interface with the antenna element 120. In the illustrated example, the via 302 directly contacts the antenna element 120, and therefore the feed point 122 is at the center of the top surface of the via 302. In other embodiments where the antenna element 120 does not physically contact the via but is capacitively coupled to the slot, the location of the feed point may be at the optimum coupling location of the slot.

[0021] For example, the via 302 may be cylindrical and have a diameter D through a central axis 425, with the intersection of the axis 425 and the antenna element 120 defining the location of the feed point 122. (If the via 302 has an elliptical cross-section, D may represent the distance across any cross-section of the ellipse.) The catch pad 406 may be deposited and patterned with a conductive material that may have a footprint with a diameter or width approximately the same as or slightly larger than the diameter D for manufacturing tolerance purposes. The RFIC 110 has an I / O pad 412 that connects to the catch pad 406 via an electrical connection joint 420s (the "s" indicates a "signal" line connection). This connection enables signal communication between the antenna element 120 and beamforming circuitry (not shown) within the RFIC 110. The I / O pad 412 may be cylindrical, elliptical, or rectangular about the central axis 435. The I / O pad location 315 may be defined as a location along the central axis 435. In the precise alignment example of FIG. 4A , the desired alignment tolerance (i.e., allowable horizontal offset due to manufacturing variations) between axis 435 and axis 425 may be approximately ¼ D. Such minimal or zero offset minimizes the signal path length between the feed point 122 location and the I / O pad location 315 for a given thickness of the antenna substrate 150 and conductive bonding material (the thickness of the connection joint 420s). This allows the antenna element 120 to be directly connected to the RFIC 110 through the via 302 and the conductive bonding material (e.g., solder) of the connection joint 420s without the need for additional transmission lines or multi-layer connections. An example diameter D of the via 302 for a millimeter-wave design is in the range of 50 to 100 μm. A typical alignment accuracy for the RFIC 110 for precise alignment may be approximately 5 μm. In a millimeter-wave design, an example diameter or width of the antenna element 120 is in the range of 1 to 2 mm, with inter-element spacing in the range of approximately 2 to 4 mm in each of the X and Y directions. The RFIC 110 may each have a length and width in the range of about 4-6 mm. The thickness (height as seen in FIG. 4A) of the RFIC 110 and underfill layer 410 may be about 3 mm, and the thickness of the antenna substrate 150 may be about 10 mm.All dimensions above are exemplary to understand the small scale typical for mmWave applications and can be varied by design and / or according to frequency and manufacturing precision.

[0022] FIG. 4A also illustrates an example of a GSG connection, with two ground connections at two locations 317 on opposite sides of the signal line's connection to the connection joint 420s. Each ground connection is made by connecting the ground pad 408 of the RFIC 110 to the ground plane 340 at location 317 via a ground connection joint 420g. An isolation layer 410 may be comprised of an underfill material surrounding each of the connection joints 420s, 420g to provide mechanical support to the connection joints 420s, 420g, thereby improving reliability. A typical underfill material may be a composite material primarily composed of amorphous fused silica. In other embodiments, the underfill material is omitted, thereby the isolation layer 410 simply representing air. To isolate the via 302 from the ground plane 340, an area of ​​the ground plane 340 surrounding the catch pad 406 is cut away, exposing the underside 453 of the antenna substrate 150. This feature is best seen in FIG. 4B, a cross-sectional view through connection joints 420s, 420g looking toward substrate 150 (with isolation layer 410 removed for clarity). Some examples of connection joints 420s and 420g are copper pillar connection joints, solder joints (e.g., formed from solder balls), and gold-gold bumping connections. As mentioned above, alternative embodiments can use GS connections with only a single ground connection on one side of the signal connection. GSG connection designs offer more isolation and reduce stray light than GS designs, but are more complex. GSG connections can have three or more ground connection joints 420g in some designs, although actual implementations have two connection joints 420g.

[0023] 4A and other figures herein, the antenna substrate 150 is shown as a single layer substrate. In other embodiments, the antenna substrate 150 is a multi-layer substrate with a patterned metal layer to provide some inter-chip RF routing between the RFICs 110 and / or connections between DC lines on the RFICs 110. In this metal layer, metal is removed in the area of ​​the vias 302 to allow direct connections between the RFICs 110 and the antenna elements 120. Note further that while a single I / O pad 412 is shown in FIG. 4A , in other embodiments, two or more I / O pads 412 connect to each antenna element 120 in an alternative manner to achieve circular polarization.

[0024] FIG. 5 is a cross-sectional view of another exemplary connection structure 500 between the antenna element 120 and the RFIC 110. In this example, the feed point 122 is “substantially aligned” but not precisely aligned with the I / O port location 315 of the RFIC 110. (This can also be considered a subset of the “aligned” configuration, as discussed above.) To this end, a wider catch pad 506 extends below the via 302, which connects only to a first portion of the catch pad 506. The signal connection joint 520s extends beyond the first portion of the catch pad 506 and below a second portion. Thus, the connection joint 520s is not directly below the via 302. This approach is advantageous when the process for forming the connection via 302 results in a non-planar bottom surface of the via 302 that can be translated to the bottom surface of the catch pad. For example, in the configuration of FIG. 4A , if the catch pad 406 has a non-planar bottom surface, the connection joint 420s may be less reliable than desired. In FIG. 5, the right portion below the via 302 may have a non-planar bottom, but replacing it with an extended catch pad 506 with a planar bottom on the left side improves reliability. As a result, a more secure connection with the connection joint 520s can be formed. The RFIC 110 in this case includes an I / O pad 512 that is symmetrical about a central axis 535. The central axis 425 of the via 302 is horizontally offset from the axis 535 by a distance d1, where a typical value of d1 may be approximately D (the diameter of the via 302). Although an offset exists between the location of the feed point 122 and the I / O pad location 315, the offset is small enough that the two locations are considered aligned. For example, in terms of wavelength, the maximum value of the offset d1 may be 0.02 wavelengths at the operating frequency of the antenna apparatus 100, which may have a negligible electrical impact on antenna performance compared to the precisely aligned embodiment of FIG. 4A.

[0025] FIG. 6 shows a cross-sectional view of an exemplary detailed connection structure 600 between the antenna element 120 and the RFIC 110 in the antenna device 100. The illustrated connection structure 600 is an example of the connection structure 500 of FIG. 5 and illustrates a closely aligned flip-chip connection in which the via 302 is slightly horizontally offset from the center point 315 of the I / O pad 612 of the RFIC 110. Alternatively, the via 302 may be precisely aligned with the I / O pad 612, in which case the configuration is a detailed example of the connection structure 400 of FIG. 4. The RFIC 110 may be a semiconductor die composed of III-V materials for microwave and millimeter-wave designs, or silicon for lower frequencies. Some examples of III-V materials include indium phosphide (InP), gallium arsenide (GaAs), silicon germanium (SiGe), and gallium nitride (GaN). An active die side region 637 of the RFIC 110, e.g., the top side region of the RFIC 110 above the imaginary line 635, faces the antenna elements 120. The active die side region 637 may include doped regions for transistors used in beamforming circuits, e.g., low noise amplifiers, power amplifiers, T / R switches, phase shifters, etc. The bottom surface 631 may be plated with metal and used as a ground for the internal circuitry of the RFIC 110.

[0026] Between the I / O pads 612 and the connection joints 520s, a surface finish metal layer 624, such as electroless nickel electroless palladium immersion gold (ENEPIG), may be present to help the liquefiable metal (e.g., solder) of the connection joints 520s adhere to the I / O pads 612. The layer 624 may be formed in the general shape of an inverted truncated cone with a central cavity on its top surface to provide a more reliable connection interface. When solder balls or other metal structures are placed and then liquefied on top of the layer 624 during a flip-chip connection formation process, some of the liquid metal fills the upper cavity. This helps form the connection joints 520s as robust connections between the catch pads 506 and the I / O pads 612. In the example of FIG. 6, the metal routing layer 616 functions as a redistribution layer to connect between circuit points within the RFIC 110 and / or between different RFICs 110. To this end, a first polymer overcoat layer 622, such as benzocyclobutene (BCB), may be formed between the top surface of the RFIC 110 and the metal routing layer 616, and a second polymer overcoat layer 614 may be formed between the metal routing layer 616 and the isolation layer 410. Layers 622 and 614 provide isolation and support for the metal routing layer 616. The material of layer 622 may overlay a peripheral portion of the I / O pads 612 as shown. If the metal routing layer 616 is omitted, the first polymer overcoat layer 622 may still be present on the top surface of the RFIC 110. The isolation layer 410 surrounds the connection joints 520s and extends between the overcoat layer 614 and the bottom surface of the antenna substrate 150. A similar connection structure may be provided to connect the ground pads 408 to a ground plane 440 (both not shown in FIG. 6 ). That is, each of the ground pads 408 may be configured similarly to the I / O pads 612, and a surface finish metal layer 624 may be present between each ground pad 408 and the corresponding connection joint 520s, similar to connection joint 420g of FIG. 6.

[0027] 6 is sufficient to provide a short, aligned connection between the feed point 122 and the I / O pad 612, but may exhibit the side effect of signal loss caused by interfacing the polymer overcoat layer 622 with the active die side of the RFIC 110. Another possible side effect results from the proximity between the active die side region 637 and the antenna ground plane 440 (seen in FIG. 4), which is located between the isolation layer 410 and the antenna substrate 150. This creates a risk of oscillation due to reflections between the ground plane 440 and the circuitry in the active die side region 637.

[0028] 7A is a cross-sectional view of an exemplary dual-via type connection structure 700 between the antenna element 120 and the RFIC 110 in the antenna device 100. (Connection structure 700 is shown flipped 180 degrees relative to that of FIGS. 3-6.) Connection structure 700 differs from structure 600 of FIG. 6 in that the active die side of the RFIC 110 does not have an interface with the polymer layer, thereby avoiding losses that would otherwise result from such an interface. Also, the connection structure is less susceptible to oscillations due to reflections between the antenna ground plane and the region on the active die side of the RFIC 110 because these regions are not further apart and face each other.

[0029] The RFIC 110 in FIG. 7A has an active die side region 737 above imaginary line 735. A first via 732 formed through the die of the RFIC 110 electrically connects to a conductive trace 724 in a localized area of ​​the active die side region 737. The localized area may be a conductive I / O node of beamforming circuitry within the RFIC 110, and the conductive trace 724 may connect to another circuit point of the beamforming circuitry. The first via 732 may be referred to as a "hot via" because it is not electrically connected to ground. The first via 732 connects at its opposite end to an I / O pad 712 located on the underside of the RFIC 110 opposite the active side region 737. The I / O pad 712 connects to the antenna element 120 at the feed point 122 via a series of conductors. These may include copper pillars 752 or gold / solder bumps, solder caps 754 (or other liquefiable metal caps), a surface finish metal layer 756 such as ENEPIG, catch pads 706, and second vias 702 formed through the antenna substrate 150. The signal connection joints 720s include copper pillars 752 and solder caps 754, where the copper pillars 752 may be formed by growing copper onto the pillars and the solder caps 754 applied as solder connections to create the signal connection joints 720s. The catch pads 706 are formed on the rear surface 453 of the substrate 150 and may be similar to the catch pads 506 of FIG. 5. A passivation layer 760, e.g., a quartz polymer layer, may surround the surface finish metal layer 756 and may be formed partially on the substrate surface 453 and partially on the exposed surfaces of the catch pads 706. As described below in the example of FIG. 7B, one or more passivation layers 760 can act as insulators between the ground plane 440 and one or more redistribution metal layers between the substrate 150 and the RFIC 110.

[0030] For example, when via 702 is formed, a non-planar surface may result near surface 453 of substrate 150, which may be translated into the adjacent area of ​​catch pad 706. Therefore, catch pad 706 may be designed to extend horizontally as shown, so that the connection joint area (layers 756, 754, and 752) to RFIC 110 may have higher strength and reliability. The same is true for via 732 and catch pad 712. Because the horizontal extensions of catch pads 706 and 712 may be similar, feed point 122 may be substantially or exactly aligned with location 315 of I / O pad 712 (i.e., aligned as defined above). Furthermore, even if catch pads 706 and 712 are not designed to extend in the same direction, the offset between the respective vias 702, 732 and the central axis of connection joint 720s is small (e.g., less than 0.02 wavelengths), so that I / O pad location 315 and antenna feed point 122 are still aligned.

[0031] An isolation layer 410 (with or without underfill material) can be disposed between the passivation layer 760 and the underside 631 of the RFIC 110. If the isolation layer 410 is comprised of underfill, the underfill does not interface with the active die region 737 of the RFIC 110, thereby avoiding signal loss that would otherwise be caused by the interface. Additionally, the likelihood of oscillation is reduced compared to the connection structure 600 of FIG. 6 because the active die region 737 is located further away from the ground plane 440 (not shown in FIG. 7, but located between the surface 453 of the substrate 150 and the isolation layer 410, as seen in FIGS. 4A, 4B, 5, and 7B). Additionally, a ground plane acting as a ground for the beam-forming circuitry within the RFIC 110 can be present on the underside 631 of the RFIC 110, further reducing the risk of oscillation.

[0032] 7B is a cross-sectional view of an exemplary portion of the antenna device 100 illustrating an exemplary extended connection structure incorporating the dual-via-type connection of FIG. 7A. The connection structure 700a includes the connection structure 700 described above, with first and second ground connection joints 720g1 and 720g2 on either side, collectively forming a GSG connection set 720. Each of the ground connection joints 720g1 and 720g2 can have the same type of structure and similar dimensions as the signal connection joint 720s. Each of the ground connection joints 720g1 and 720g2 can electrically connect a respective localized region of the ground plane 708 of the RFIC 110 to a connection point on the ground plane 440. A local surface finish layer 756 can be applied to the ground plane 440 to help the ground connection joints 720g1 and 720g2 adhere to the ground plane 440.

[0033] 7B also shows a redistribution layer (RDL) 788 that may be present between the RFIC 110 and the ground plane 440. The redistribution layer 788 may be used to connect circuit points within the RFIC 110 and / or circuit points of different RFICs 110, typically to route DC bias between the circuit points. The RDL 788 is formed on an area of ​​the protection layer 760 and separates the protection layer from the ground plane 440. A connection joint 790, which may have the same type of structure as the signal connection joints 720s, may connect I / O pads 792 of the RFIC 110 to the RDL 788. The RDL 788 extends horizontally and may connect to another I / O pad of the RFIC 110 (not shown) or a different RFIC 110 via another connection joint 790 to route signals / DC voltages between different circuit points of the RFIC(s) 110. If at least one additional RDL 788 is added to the configuration of the antenna device 100, an additional passivation layer 760 may be disposed on one or both sides of each additional RDL to provide the necessary isolation between the RDLs.

[0034] FIG. 8A shows an exemplary arrangement 800a of antenna element feed point locations relative to connected RFICs within the antenna apparatus 100. In this example, the RFIC 110 is connected to four antenna elements 120-a, 120-b, 120-c, and 120-d arranged as part of a triangular lattice, referenced to a center point 123 of the antenna elements. The center point 123 may also be referred to interchangeably herein as the phase center 123 of each antenna element. The RFIC 110 is arranged as part of a rectangular lattice, as previously shown in FIGS. 1 and 2. The antenna elements 120-a through 120-d are each illustrated as a circular patch element having slits 811 (elongated slots) extending from an open end at the periphery of the antenna element to a closed end toward the center point 123. The antenna elements 120-a through 120-d are connected to the RFIC 110 via feed points 122-a, 122-b, 122-c, and 122-d, respectively. Note that the "x" within the "o" representing feed point 122 represents an I / O pad of RFIC 110, such as any of I / O pads 412, 512, 624, or 712 described above.

[0035] Instead of feeding each antenna element 120 at its center point 123, the feed points 122-a to 122-d in each group of four antenna elements connected to the RFIC 110 are offset in different directions from the center point 123, and the slits 811 are aligned in correspondingly different directions. The patch design may be the same for each of the four antenna elements 120-a to 120-d, or may be rotated in 90-degree increments between antenna elements. This rotation in the patch design from the antenna elements 122-a to 122-d advantageously creates pattern diversity and a circular polarization with a low axial ratio. The location and dimensions of each slit 811 and the relative positions of adjacent feed points 122 are designed to create a circular polarization for the corresponding antenna element 120. To this end, the length of each slit 811 may be in the range of 1 / 4 to 3 / 4 of the radius of the antenna element 120. In one example, each slit 811 is approximately 2 / 3 of the radius. Each of the feed points 122-a to 122-d is offset laterally from the side of the adjacent slit 811 closer to the closed end.

[0036] The local coordinate system of the RFIC 110, which has a rectangular footprint, may be defined by an X-axis parallel to the top and bottom edges of the rectangular footprint and a Y-axis parallel to the left and right edges, with the center point 113 as the origin. The local coordinate system of each of the antenna elements 120-a through 120-d may be defined by an X-axis parallel to the X-axis and a Y-axis parallel to the Y-axis, with the center point 123 as the origin. The antenna elements 120-a and 120-b have the same +X coordinate and are arranged in an upper row, separated by X1 in the column direction. The antenna elements 120-c and 120-d are in a lower row at the same -Y level, separated by X1 in the column direction, and separated by Y1 from the upper row. The slits 811 of the antenna elements 120-a through 120-d and the corresponding feed points 122-a through 122-d are rotated by 90°. Thus, feed points 122-a, 122-b, 122-c, and 122-d are each located in a different quadrant of the local x-y coordinate system. In this example, feed points 122-a through 122-d are in the lower-left (-x, -y), upper-left (+y, -x), upper-right (+x, +y), and lower-right (+x, -y) quadrants, respectively. Each feed point 122 is offset in the x and y directions from its respective center point 123 by Δx and Δy. In the y direction, within each column, the feed points have a y-axis variation of 2Δy. In the x direction, there is a column-to-column variation of 2Δx compared to feeding all antenna elements at center point 123.

[0037] 8A, the axial ratio and pattern diversity are improved by rotating the patch design, which results in variation in the location of the feed points 122 from quadrant to quadrant relative to the center 123 of the antenna elements 120. However, because the feed points of each column vary in the y-direction, the layout of the beamforming circuitry within the RFIC 110 is asymmetric, making circuit layout and packaging more complex and difficult.

[0038] FIG. 8B shows another exemplary arrangement 800b of antenna element feed point locations relative to the connected RFIC 110 within the antenna device 100. This arrangement differs from arrangement 800a in that the feed points 122 in each row have the same Y coordinate, which allows for a simpler beamforming circuit layout. As with arrangement 800a, the RFIC 110 is connected to four antenna elements 120-a, 120-b, 120-c, and 120-d, which, for comparison, can be assumed to have the same footprint and relative positions as in FIG. 8A. Each feed point 122 is also shown offset by Δx and Δy from its adjacent center point 123. However, in device 800b, in the top row, feed point 122-a is in the upper left quadrant, and feed point 122-b is in the upper right quadrant. Therefore, the X-spacing between these feed points is (X1 + 2Δx), which is 2Δx wider than that of arrangement 800a. Similarly, in the bottom row, feed point 122-c is in the lower-left quadrant and feed point 122-d is in the lower-right quadrant, and the X spacing between these feed points is also (X1+2Δx). Furthermore, in the Y direction, the spacing between feed points 122 in the top and bottom rows is uniform (Y1+2Δy). Note also that the position of slit 811 relative to the quadrant position of feed point 122 is the same as in layout 800a.

[0039] Thus, for a given RFIC 110 having I / O pad locations according to arrangement 800b, the I / O pad locations (corresponding to feed point 122 locations) are further apart in both the X and Y directions compared to the spacing between center points 123. This is also true for arrangement 800a when considering the maximum X and Y spacing between any two feed points 122. Thus, assuming the same beamforming circuitry in the RFIC 110 of arrangement 800b versus 800a, the same rectangular footprint of the RFIC 110 may be typical.

[0040] 8C illustrates yet another exemplary arrangement 800c of antenna element feed point locations relative to the connected RFIC 110 within the antenna apparatus 100. In this embodiment, the same relative locations of the antenna elements 120-a through 120-d may be assumed, i.e., an intra-column antenna element 120 spacing of X1 and an inter-column spacing of Y1. However, in configuration 800c, the feed points 122-a, 122-b, 122-c, and 122-d are located in the lower right, lower left, upper right, and upper left quadrants, respectively. This reduces the X-spacing (X1-2Δx) between the top-most row of feed points 122-a and 122-b and the bottom-most row of feed points 122-c and 122-d. Furthermore, the inter-column Y-spacing between the feed points 122 is also reduced to (Y1-2Δy). Thus, in configuration 800c, the corresponding I / O pads (the "x" in feed point 122 represents either I / O pad 412, 512, etc.) can use a smaller rectangular footprint of RFIC 110, if packaging of the beamforming components allows.

[0041] Accordingly, aspects of configurations 800a, 800b, and 800c can be summarized as follows: Each RFIC 110 includes a plurality of N I / O pads connected to a corresponding plurality of feed points of a group of N circularly polarized antenna elements. A first antenna element of the group has at least one feed point offset from its center point in a first direction, and a second antenna element of the group has at least one feed point offset from its center point in a second, different direction, the first and second directions being defined relative to a common coordinate system. Each group may be a group of four antenna elements connected to a single RFIC. When there are four antenna elements in each group, each of the four antenna elements has a feed point offset from the center of its respective antenna element in a different direction relative to the common coordinate system from any of the other antenna elements of the four. Each of the antenna elements of a group may have the same design configuration, including a slit and at least one feed point offset laterally from an edge of the slit to generate circular polarization for transmit and / or receive operation. Each of the second to fourth antenna elements of the group of four antenna elements can be rotated by K times 90° relative to the first antenna element of the group, where K ranges from 1 to 3 and is different for each of the second to fourth antenna elements.

[0042] 9 illustrates an example layout of beamforming circuitry within an RFIC 110 having I / O pads arranged according to arrangement 800b of FIG. 8B. In this example, the RFIC 110 has four GSG I / O pad connection sets (“GSG sets”) 940-a, 940-b, 940-c, and 940-d, each having a signal I / O pad (“S pad”) 912 and a pair of ground (“G”) pads 408 on either side of the S pad 912. Thus, each of GSG sets 940-a through 940-d can be linearly aligned first and second sets of ground pads and signal pads that collectively form an elliptical profile having a major axis and orthogonal minor axes, where the major axes are substantially parallel to the left and right edges of the respective RFIC 110.

[0043] Each S pad 912 may be configured as any of the I / O pads 412, 512, 624, or 712 described above, and each G pad 408 may be configured as any of the G pads 408 of FIG. 4. Each S pad 912 is connected to a corresponding feed point 122-a through 122-d using any of the connection structures described above for the I / O pads 412, 512, etc. Thus, each S pad 912 is aligned with a respective feed point 122-a, 122-b, 122-c, and 122-d. In each GSG set 940-a through 940-d, the G pads 408 and S pads 912 may be linearly aligned in the Y direction.

[0044] The first power amplifier region 920-1 may be located between GSG sets 940-a and 940-b, and the second power amplifier region 920-2 may be located between GSG sets 940-c and 940-d. Each GSG set 940-a through 940-d may be connected to the output or input of a respective amplifier 903 in the adjacent amplifier region 920-1 or 920-2. In the illustrated example, the amplifiers 903 are transmit power amplifiers, and each GSG set is connected to the output port of the amplifier 903. In another example, some of the amplifiers 903 are PAs and others are LNAs. In the latter case, any given GSG set 940 may be connected to the input of the LNA.

[0045] A circuit area 950 having additional beamforming circuitry may be located outside of areas 920-1 and 920-2. For example, each amplifier 903 may be connected to a respective bandpass filter 905 and phase shifter 907 in circuit area 950. Generally speaking, amplifiers 903, in conjunction with the beamforming circuitry in circuit area 950, condition (e.g., amplify, phase shift, filter, etc.) signals input / output from GSG set 940 (output from antenna elements 120 to receive / antenna elements). Circuit area 950 may further include at least one combiner / divider 910 comprised of one or more RF couplers (e.g., 3 dB directional couplers) for combining and / or dividing signals received / transmitted from at least two antenna elements 120.

[0046] The GSG sets 940-a and 940-d are located near the upper left and lower right corners of the RFIC 110, respectively. These locations may be located as close to the left and right edges of the RFIC 110 (as shown in FIG. 9 ) as possible, as long as the design rules of the foundry that manufactures the RFIC 110 permit. The GSG sets 940-a and 940-b may be located at the same Y level near the top edge of the RFIC 110. The GSG sets 940-c and 940-d may be located at the same -Y level near the bottom edge. The GSG set 940-b may have a center coordinate in the X direction approximately midway between the GSG sets 940-c and 940-d. Similarly, the GSG set 940-c may have a center coordinate in the X direction approximately midway between the GSG sets 940-a and 940-b. Once each GSG set 940 is aligned with a corresponding feed point 122 of the antenna element 120 as described above, the positions of the GSG sets 940 are aligned with the triangular lattice points 123 of the antenna element 120, as shown in FIG. 2 . This configuration differs from standard RFIC chips, which typically have all I / O pads located symmetrically adjacent to opposite edges of their rectangular footprints. For example, in standard RFIC chips, GSG set 940-c is located in the lower left corner, and GSG set 940-b is located in the upper right corner. The configuration of FIG. 9 , which moves some of the GSG sets inward from the corners, allows for alignment of the GSG sets with the antenna feed points 122.

[0047] While the technology described herein has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details can be made therein without departing from the spirit and scope of the claimed subject matter as defined by the following claims and their equivalents.

Claims

1. An antenna device, a first component layer including a plurality of radio frequency integrated circuit chips (RFICs) arranged in a first plane having a first grid arrangement, each RFIC including beamforming circuitry; a second component layer overlaid on the first component layer and including a plurality of antenna elements arranged in a second plane parallel to the first plane, the second component layer having a second, different lattice arrangement, the antenna elements each having a respective feed point connected to an input / output (I / O) pad of an RFIC, each I / O pad connected to and aligned with the feed point along an axis orthogonal to the first and second planes; An antenna device comprising:

2. 2. The antenna apparatus of claim 1, wherein the first grid arrangement is rectangular and the second grid arrangement is triangular.

3. 10. The antenna apparatus of claim 1, further comprising: an antenna substrate between the first and second component layers; and a plurality of vias extending through the antenna substrate, each of the vias connecting one of the antenna elements to one of a plurality of I / O pads of the RFIC.

4. 4. The antenna apparatus of claim 3, wherein the plurality of I / O pads are flip-chip I / O pads, each flip-chip I / O pad electrically connected to one of the vias through a flip-chip electrical connection joint, and an active die side of each RFIC facing the antenna substrate.

5. the flip-chip electrical connection joint is surrounded by an underfill layer between the antenna substrate and the second component layer; The antenna device of claim 4 , further comprising a polymer overcoat layer between the second component layer and the underfill layer.

6. The antenna device according to claim 3 , wherein an active die side of each IC chip faces the antenna substrate.

7. the plurality of vias are a plurality of first vias, The antenna device includes: a plurality of second vias, each extending from a non-active side of the RFIC to an active side of the RFIC; 7. The antenna apparatus of claim 6, further comprising: a plurality of electrical connection joints, each of which connects an end of a first via to an end of a second via.

8. The antenna device of claim 7 , wherein each of the plurality of electrical connection joints is surrounded by an underfill layer between the antenna substrate and the second component layer.

9. The antenna apparatus according to claim 1 , wherein each of the RFICs includes a plurality of N I / O pads connected to a corresponding plurality of feed points of the N antenna elements.

10. each of the antenna elements is a circularly polarized patch antenna element; 10. The antenna apparatus of claim 9, wherein a first antenna element of the plurality of antenna elements has at least one feed point offset from a center of the first antenna element in a first direction, and a second antenna element of the plurality of antenna elements has at least one feed point offset from a center of the second antenna element in a second direction different from the first direction, and the first and second directions are defined relative to a common coordinate system.

11. 10. The antenna device of claim 9, wherein the antenna elements are arranged in groups of four antenna elements connected to a single IC chip, and in each of the groups, each of the four antenna elements has a feed point offset from the center of the respective antenna element in a different direction from any of the other antenna elements of the four antenna elements relative to a common coordinate system.

12. each of the antenna elements of a group has the same design configuration having a slit and at least one feed point laterally offset from an edge of the slit to generate the circular polarization for transmit and / or receive operation; 12. The antenna arrangement of claim 11, wherein each of the second to fourth antenna elements of the four antenna elements of a group is rotated by K×90° with respect to the first antenna element of the group, where K is in the range of 1 to 3 and is different for each of the second to fourth antenna elements.

13. The antenna apparatus of claim 1 further comprising a ground plane between the first and second component layers.

14. the first lattice arrangement is rectangular, the second lattice arrangement is triangular, and the antenna device is an antenna substrate between the first component layer and the second component layer; a plurality of vias extending through the antenna substrate, each via connecting a feed point of one of the antenna elements to one of the I / O pads; 2. The antenna apparatus of claim 1, wherein the antenna elements are arranged in a plurality of groups of N antenna elements connected to a single respective RFIC, and in each group, each of the N antenna elements has a feed point that is offset from a center of the respective antenna element in a direction that is different from a feed point offset direction of any other antenna element among the N antenna elements, relative to a common coordinate system.

15. 15. The antenna arrangement of claim 14, wherein N is equal to 4.

16. 15. The antenna apparatus of claim 14, further comprising a ground plane between the antenna substrate and the second component layer.

17. 15. The antenna apparatus of claim 14, wherein each RFIC includes first, second, third, and fourth ground-to-signal-to-ground I / O pad connection sets (“GSG sets”), the signal I / O pads of each GSG set connected to the feed point of a respective antenna element, and the first and second ground pads of each GSG set each connected to the ground plane.

18. each RFIC of the RFICs has a rectangular profile with a top edge, a bottom edge, a left edge, and a right edge, an X direction being parallel to the top and bottom edges, and a Y direction being parallel to the left and right edges; the first GSG set is located in the upper left corner of the RFIC and the fourth GSG set is located in the lower right corner of the RFIC; the second GSG set has a Y coordinate proximate the top edge and an X coordinate approximately midway between the X coordinates of the third GSG set and the fourth GSG set; 18. The antenna apparatus of claim 17, wherein the third GSG set has a Y coordinate proximate to the bottom edge and an X coordinate approximately midway between the X coordinates of the first GSG set, the second GSG set, and the fourth GSG set.

19. 20. The antenna apparatus of claim 18, wherein each of the GSG sets is a linearly aligned set of first and second ground pads and signal pads that collectively form a rectangular profile having a major axis and an orthogonal minor axis, the major axis being substantially parallel to the left and right edges of the respective RFIC.

20. The antenna device according to claim 14, wherein the beam forming circuit is a millimeter wave front end circuit.

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