AND METHOD PRIORITY

This patent application claims priority from provisional United States patent application number 62/ 610,227, filed December 24, 2017, entitled,

' BEAMFORMING INTEGRATED CIRCUIT AND AESA," and naming Pavel Brechko, David Corman, Vipul Jain, Shamsun Nahar, Jason Durbin, and Nitin Jain as inventors, the disclosure of which is incorporated herein, in its entirety, by reference.

FIELD OF THE INVENTION

The invention generally relates to active electronically scanned/ steered arrays (AESAs) and, more particularly, to beamforming integrated circuits for AESAs.

BACKGROUND

Active electronically steered/ scanned antenna systems ("AESA systems," a type of "phased array system") or active antenna systems form electronically steerable beams for a wide variety of radar and communications systems. To that end, AESA systems typically have a plurality of beam-forming elements (e.g., antennas) that transmit and/ or receive energy so that such energy can be coherently combined (i.e., in-phase and amplitude). This process is referred to in the art as "beamforming" or "beam steering." Specifically, for transmission, many AESA systems implement beam steering by providing various RF phase shift and gain settings. The phase settings and gain weights together constitute a complex beam weight between each beam-forming element. For a signal receiving mode, many AESA systems use a beamforming or summation point.

To achieve beam-forming using an antenna array, each antenna element is connected to a semiconductor integrated circuit generally referred to as a "beam- forming IC." This microchip/ integrated circuit may have a number of sub- circuit components implementing various functions. For example, those components may implement phase shifters, amplitude control modules or a variable gain amplifier (V G A), a power amplifier, a power combiner, a digital control, and other electronic functions. Such an integrated circuit is packaged to permit input and output radio frequency (RF) connections.

SUMMARY OF VARIOUS EMBODIMENTS OF THE INVENTION

In accordance with illustrative embodiments, a method of transmitting a signal using beamforming provides providing a beamforming integrated circuit for use with an AESA. The integrated circuit includes a plurality of RF transmit channels, and each of the RF transmit channel has a first input configured to receive a signal, a phase controller configured to shift the phase of the first signal, an amplifier configured to amplify the signal, and an output configured to forward the signal to a transmit element of the AESA. The integrated circuit also has at least one power input.

The method further receives an energizing signal though the power input, and operates the integrated circuit at a quiescent current with the received energizing signal so that the integrated circuit operates at an RF power value within a prescribed range of RF power values. In preferred embodiments, the RF power value does not exceed about 10 dBm in output PldB, and is greater than about -3 dBm. The RF power value may be between X dBm and Y dBm, where X is between 1-9.7 and Y is between 1-9.8. X preferably is less than Y for the selected values of X and Y. As such, the RF power value may be between one or more of the following ranges:

4-9 dBm,

4-8 dBm,

4-7 dBm,

4-6 dBm,

4-5 dBm.

The integrated circuit may have a surface with a plurality of interface ports. This surface has a first edge and a second edge and a first RF interface port adjacent or at the first edge, and a second RF interface port adjacent to or at the second edge. The first and second RF interface ports may be configured to operate on signals havssing different polarizations. For example, the first RF interface port may be configured to interface with signals that are orthogonal to signals upon which the second RF port interfaces. The integrated circuit may have a quiescent DC power of between about 50 and about 80 milliwatts for each channel.

In accordance with another embodiment, a beamforming integrated circuit for use with an AESA has a plurality of RF transmit channel. Each of the RF transmit channel has a first input configured to receive a signal, a phase controller configured to shift the phase of the first signal, an amplifier configured to amplify the signal, and an output configured to forward the signal to a transmit element of the AESA. The integrated circuit also has at least one power input for receiving an energizing signal that energizes the plurality of RF transmit channels. The integrated circuit is configured to operate at an RF power using the energizing signal. The integrated circuit preferably is configured to operate so that the RF power has a value not exceeding about 10 dBm, and not less than about -3 dBm.

In accordance with other embodiments, a beamforming integrated circuit system configured to receiving and/ or transmitting a beam has a plurality of RF ports, and a plurality of RF circuitry channels for transmitting and/ or receiving RF signals. Each of the RF circuitry channels is operatively coupled with at least one of the RF ports. The system also has a channel controller operatively coupled with the plurality of RF circuitry channels. The channel controller is configured to selectively turn on and off one or more sub-sets of the plurality of the RF circuitry channels to control the system in a prescribed manner.

The system may include a unitary integrated circuit body containing the plurality of RF circuitry channels, plurality of RF ports, and channel controller. Alternatively, unitary body may not include the channel controller. In that case, the system may include a second integrated circuity body containing the channel controller. In that latter case, the unitary and second integrated circuit bodies are configured to communicate with each other.

The channel controller may be configured to selectively turn on and off one or more sub-sets of the plurality of the RF circuitry channels to control a variety of different system functions. For example, it may be configured to control the shape or magnitude of a transmitted or received beam, enable distribution or combination of signals from different beamforming integrated circuits in an AES A, and/ or control power consumption in a prescribed manner.

The channel controller may control the selective use of the RF circuitry channels before transmitting or receiving, or while transmitting or receiving.

In accordance with another embodiment, a method of controlling a system function energizes a beamforming integrated circuit having a plurality of RF circuitry channels for transmitting and/ or receiving RF signals, and determines a desired system function. The method then selectively turns on and off one or more sub-sets of the plurality of the RF circuitry channels to control the desired system function.

A first RF circuitry channel of the plurality of RF circuitry channels may have a first selectable phase shifter configured to shift a first signal, and a second RF circuitry channel of the plurality of RF circuitry channels may have a second selectable phase shifter configured to shift a second signal. The method further may select the phase shift of the first signal by selecting the first phase shifter and the phase shift of the second signal by selecting the selecting phase shifter;. Next, a combiner may receive the shifted first and second signals from the first and second channels, and combine the first and second shifted signals to produce a combined signal. The first and second phase controllers thus are selected so that the combined signal has one of a plurality of different selectable polarizations.

In accordance with still other embodiments, a beamforming integrated circuit for use with an AESA has a unitary body with an interface surface and a wafer level chip-scale package. The integrated circuit also has beamforming RF circuitry configured to process signals for transmitting and/ or receiving RF signals, and a plurality of RF interfaces operatively coupled with the RF circuitry and on the interface surface. The plurality of RF interfaces are configured for communicating the signals with the plurality of elements of the AESA. Each of the RF interfaces is RF isolated from each other by having at least one adjacent ground interface.

Each RF interface may be adjacent to at least two ground interfaces. In some embodiments, the unitary body comprises an edge, and each RF interface is adjacent to the edge and at least one ground interface. The at least one ground interface also may be adjacent to the edge. Each RF interface has an outside dimension that preferably is adjacent to at least one ground interface and the edge only.

The unitary body may include an edge and each RF interface may be positioned between two ground interfaces. In that case ,the two ground interfaces and RF interface can be adjacent to the edge of the unitary body.

To optimize the integrated circuit, it may also have a plurality of power interfaces that are radially inward of the RF interfaces having an adjacent ground interface. Moreover, each RF interface and its adjacent ground interface preferably defines a space of between about 300 and 400 microns. The noted RF isolation preferably mitigates noise and cross-talk between RF interface pads at microwave and millimeter-wave frequencies.

In accordance with other embodiments, a beamforming integrated circuit for use with an AESA has a unitary body that includes a wafer level chip-scale package. The integrated circuit also has beamforming RF circuitry within the wafer level chip-scale package configured to process signals for transmitting and/ or receiving RF signals, and a plurality of RF interfaces on the wafer level chip-scale package and operatively coupled with the RF circuitry. The plurality of RF interfaces are adjacent to an edge of the body. In addition, a plurality of ground interfaces may be positioned on the wafer level chip-scale package relative to the RF interfaces to isolate the RF interfaces from other RF interfaces.

In accordance with other embodiments, a phased array system has a plurality of beamforming elements, and a plurality of beamforming integrated circuits ("ICs"). A first set of the beamforming ICs are in communication with the beamforming elements, and a second set of the beamforming ICs are "node ICs" configured to combine and/ or distribute signals toward/ from a plurality of the beamforming ICs in the first set. While of the plurality of beamforming ICs have a first number of signal interfaces, the node ICs may at least one signal interface that is electrically uncoupled. For example, one or more of the signal interfaces of the node ICs may be coupled with either a) other node ICs, b) first set ICs, or c) Wilkinson, and the total number of other node ICs, first set ICs, and/ or Wilkinson coupled with a given node ICs may be less than the total number of signal interfaces.

As like ICs, the first and second sets of beamforming ICs have

substantially the same functional elements. For example, the first and second sets of beamforming ICs may have the same number of interfaces, and/ or the same types of beamforming ICs with substantially the same electrical characteristics. Moreover, the node ICs are configured to combine signals and not distribute signals, or they may be configured to distribute signals and not combine signals. To improve beam fidelity, at least one of the node ICs may be configured to amplify and/ or phase shift signals.

In accordance with another embodiment, a phased array system may have a substrate, a plurality of beamforming elements on the substrate, and a plurality of beamforming integrated circuits ("ICs"). A first set of the beamforming ICs are in communication with the beamforming elements, while a second set of the beamforming ICs are "node ICs." The system also has a first transmission line electrically between a first node IC and a first beamforming IC in the first set, and a second transmission line electrically between the first node IC and a second beamforming IC in the first set. The first node IC is configured to distribute and/ or combine signals toward/ from the first and second

beamforming ICs.

BRIEF DESCRIPTION OF THE DRAWINGS Those skilled in the art should more fully appreciate advantages of various embodiments of the invention from the following "Description of Illustrative Embodiments/' discussed with reference to the drawings

summarized immediately below.

Figure 1 schematically shows an active electronically steered antenna system ("AESA system") configured in accordance with illustrative

embodiments of the invention and communicating with a satellite.

Figures 2A and 2B schematically show generalized diagrams of an AESA system that may be configured in accordance with illustrative embodiments of the invention.

Figure 3A schematically shows a plan view of a laminar printed circuit board portion of an AESA configured in accordance with illustrative

embodiments of the invention.

Figure 3B schematically shows a close-up of a portion of the laminated printed circuit board of Figure 3A.

Figure 3C schematically shows a plan view of a laminar printed circuit board portion of an AESA configured in a rectangular lattice in accordance with illustrative embodiments of the invention.

Figure 4 schematically shows a cross-sectional view of the laminated printed circuit board of 3A to highlight the mounting of its integrated circuits.

Figure 5 schematically shows details of a receive beamforming integrated circuit in accordance with illustrative embodiments of the invention.

Figure 6 schematically shows details of a transmit beamforming integrated circuit in accordance with illustrative embodiments of the invention.

Figure 7 shows a process of using lower power in accordance with illustrative embodiments of the invention. Figures 8A and 8B respectively show a controller separate from and integrated into a beamforming integrated circuit in accordance with illustrative embodiments of the invention.

Figure 9 shows a process selectively disabling channels in accordance with illustrative embodiments of the invention.

Figure 10 schematically shows a plan view of interfaces of a beamforming integrated circuit in accordance with illustrative embodiments of the invention.

Figure 11 schematically shows a layout of beamforming integrated circuits across an AESA substrate in accordance with illustrative embodiments of the invention.

Figure 12 shows an example of digital transactions in accordance with illustrative embodiments of the invention.

Figure 13 schematically demonstrates a single channel and a simplified version of its two branches connected with a single element.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

In illustrative embodiments, a set of multi-channel (e.g., quad-channel) beam-forming integrated circuits ("ICs") have either transmit or receive functionality and dual polarization outputs. The ICs are configured to be highly flexible while remaining small enough to fit within the lattice for a planar active electronically steered/ scanned antenna systems ("AESA systems") intended for satellite communication applications. Among other things, the ICs may have an arrangement of RF outputs with optimized isolation between ports, independent double-polarization channels with independent phase, amplitude and bias controls, and a flip-chip, wafer level chip-scale packaging arrangement. With this high degree of flexibility, the ICs may be used as 1) a

beamforming IC in an AESA system enabling arbitrary polarization (e.g., linear, circular, elliptical), and/ or 2) a distribution IC in arrays, simultaneously enabling amplification as well as signal combining/ division function. In both cases, the IC can provide phase and amplitude correction in the system, shape an output beam, and/ or optimize power dissipation of the array (e.g., selectively disabling channels).

ICs can be lower power than those in the prior art and yield the same or improved beams, while selectively disabling channels to control beam shape and reduce power. Moreover, rather than using a customized integrated circuit, some AESA systems can use beamforming ICs as distribution or transmission nodes for multiple beamforming ICs. Details of illustrative embodiments are discussed below.

Figure 1 schematically shows an AESA system 10 configured in

accordance with illustrative embodiments of the invention and communicating with an orbiting satellite 12. A phased array (discussed below and identified by reference number "10A" at least in Figure 3) implements the primary

functionality of the AESA system 10. Specifically, as known by those skilled in the art, the phased array 10A forms one or more of a plurality of electronically steerable beams that can be used for a wide variety of applications. As a satellite communication system, for example, the AESA system 10 preferably is configured to operate at one or more satellite frequencies. Among others, those frequencies may include the Ka-band, Ku-band, and/ or X-band.

The AESA system 10 may be part of a cellular network operating under a known cellular protocol, such as the 3G, 4G, or 5G protocols. Accordingly, in addition to or instead of communicating with satellites, the system may communicate with earth-bound devices, such as smartphones or other mobile devices, using any of the 3G, 4G, or 5G protocols. As another example, the satellite communication system may transmit/ receive information between aircraft and air traffic control systems. Of course, those skilled in the art may use the AESA system 10 (implementing the noted phased array 10A) in a wide variety of other applications, such as broadcasting, optics, radar, etc. Some embodiments may be configured for non-satellite communications and instead communicate with other devices, such as smartphones (e.g., using 4G or 5G protocols). Accordingly, discussion of communication with orbiting satellites 12 is not intended to limit all embodiments of the invention.

Figures 2A and 2B schematically show generalized diagrams of the AESA system 10 configured in accordance with illustrative embodiments of the invention. Specifically, Figure 2A schematically shows a block diagram of the AESA system 10, while Figure 2B schematically shows a cross-sectional view of a small portion of the same AESA system 10 across line B-B. This latter view shows a single silicon integrated circuit 14 (elements 18, discussed below) mounted onto a substrate 16 between two transmit and/ or receive elements 18, i.e., on the same side of a supporting substrate 16 and juxtaposed with the two elements 18. In alternative embodiments, however, the integrated circuit 14 could be on the other side of the substrate 16. The phased array 10A also has a polarizer 20 to selectively filter signals to and from the phased array 10A, and a radome 22 to environmentally protect the phased array 10A. A separate antenna controller 24 electrically connects with the phased array 10A to calculate beam steering vectors for the overall phased array 10A, and to provide other control functions.

Figure 3A schematically shows a plan view of a primary portion of an

AESA system 10 that may be configured in accordance with illustrative embodiments of the invention. In a similar manner, Figure 3B schematically shows a close-up of a portion of the phased array 10A of Figure 3A.

Specifically, the AESA system 10 of Figure 3A is implemented as a laminar phased array 10A having a laminated printed circuit board 16 (i.e., acting as the substrate and also identified by reference number "16") supporting the above noted plurality of elements 18 and integrated circuits 14. The elements 18 preferably are formed as a plurality of square or rectangular patch antennas oriented in a triangular patch array configuration. In other words, each element 18 forms a triangle with two other adjacent elements 18. When compared to a rectangular lattice configuration, this triangular lattice configuration requires fewer elements 18 (e.g., about 15 percent fewer in some implementations) for a given grating lobe free scan volume. Other embodiments, however, may use other lattice configurations, such as a pentagonal configuration or a hexagonal configuration. Moreover, despite requiring more elements 18, some

embodiments may use a rectangular lattice configuration. Like other similar phased arrays, the printed circuit board 16 also may have a ground plane (not shown) that electrically and magnetically cooperates with the elements 18 to facilitate operation.

In contrast to the triangular arrangement of Figure 3A, Figure 3C shows a rectangular arrangement of elements 18 where each element is excited at two orthogonal positions for different possible excitations— H and V excitation. The dots on line 26 represent Wilkinson's or a power divider.

Indeed, the array shown in Figures 3A and 3B is a small phased array 10A. Those skilled in the art can apply principles of illustrative embodiments to laminar phased arrays 10A with hundreds, or even thousands of elements 18 and integrated circuits 14. In a similar manner, those skilled in the art can apply various embodiments to smaller phased arrays 10A. As a patch array, the elements 18 have a low profile. Specifically, as known by those skilled in the art, a patch antenna (i.e., the element 18) typically is mounted on a flat surface and includes a flat rectangular sheet of metal

(known as the patch and noted above) mounted over a larger sheet of metal known as a "ground plane." A dielectric layer between the two metal regions electrically isolates the two sheets to prevent direct conduction. When energized, the patch and ground plane together produce a radiating electric field.

Illustrative embodiments may form the patch antennas using conventional printed circuit board fabrication processes, such as by depositing one or more successive metal layers on the printed circuit board 16. Accordingly, using such fabrication processes, each radiating element 18 in the phased array 10A should have a very low profile.

The AESA system 10 can have one or more of any of a variety of different functional types of elements 18. For example, the AESA system 10 can have transmit-only elements 18, receive-only elements 18, and/ or dual mode receive and transmit elements 18 (referred to as "dual-mode elements 18"). Each element 18 also may have dual polarization, whether in receive mode, transmit mode, or both. For significant flexibility, illustrative embodiments may have dual-mode dual polarization, which is transit and receive; and in addition having horizontal and vertical polarization as shown in Figure 3C. The transmit-only elements 18 are configured to transmit outgoing signals (e.g., burst signals) only, while the receive-only elements 18 are configured to receive incoming signals only. In contrast, the dual-mode elements 18 are configured to either transmit outgoing burst signals, or receive incoming signals, depending on the mode of the phased array 10A at the time of the operation. Specifically, when using dual-mode elements 18, the phased array 10A can be in either a transmit mode, or a receive mode. In each of the transmit or received mode, the element 18 and IC 14 can also support dual polarization. The noted controller 24 at least in part controls the mode and operation of the phased array 10A, as well as other array functions. Tx and Rx chips are kept separate to maximize performance by eliminating loss of unnecessary Tx/Rx switches and also to account for the fact that often antenna arrays for Tx and Rx have different sizes due to different transmit and receive frequencies.

The AESA system 10 has a plurality of the above noted integrated circuits 14 (noted with regard to Figure 2B) for controlling operation of the elements 18. Those skilled in the art often refer to these integrated circuits 14 as "beam steering integrated circuits" or "beamforming integrated circuits" ("BFICs").

To minimize its footprint, each integrated circuit 14 preferably is configured with at least the minimum number of functions to accomplish the desired effect. Indeed, integrated circuits 14 for dual mode elements 18 are expected to have some different functionality than that of the integrated circuits 14 for the transmit-only elements 18 or receive-only elements 18. Accordingly, integrated circuits 14 for such non-dual-mode elements 18 may have a smaller footprint than the integrated circuits 14 that control the dual-mode elements 18. Despite that, some or all types of integrated circuits 14 fabricated for the phased array 10A can be modified to have a smaller footprint. In some embodiments, separate transmit-only and receive only integrated circuits 14 may enhance performance by eliminating loss of unnecessary transmit/ receive switches, and also to account for the fact that often AESAs for transmit purposes and receive purposes often have different sizes.

As an example, depending on its role in the phased array 10A, each integrated circuit 14 may include some or all of the following functions:

• phase shifting,

• amplitude controlling/ beam weighting, • switching between transmit mode and receive mode,

• output amplification to amplify output signals to the elements 18,

• input amplification for received RF signals (e.g., signals received from the satellite 12), and

• power combining/ summing and splitting between elements 18.

Indeed, some embodiments of the integrated circuits 14 may have additional or different functionality, although illustrative embodiments are expected to operate satisfactorily with the above noted functions. Those skilled in the art can configure the integrated circuits 14 in any of a wide variety of manners to perform those functions. For example, the input amplification may be performed by a low noise amplifier, the phase shifting may use conventional active or passive phase shifters, and the switching functionality may be implemented using conventional transistor-based switches. These and additional details of the structure and functionality of integrated circuits 14 are discussed below with reference to Figures 5 and 6.

As noted above, the AESA system 10 preferably communicates with one or more orbiting satellites 12 and thus, uses satellite frequencies for that communication. Accordingly, the plurality of integrated circuits 14 preferably are configured operate the phased array 10A at one or more frequencies of the Ka-band, Ku-band, and/ or X-band to communicate with at least one satellite 12. Of course, as satellite communication technology progresses, future

implementations may modify the frequency bands of the integrated circuits 14 to communicate using new satellite frequencies.

Multiple elements 18 preferably share the integrated circuits 14, thus reducing the required total number of integrated circuits 14. This reduced number of integrated circuits 14 correspondingly reduces the required size of the printed circuit board 16, which reduces the cost of the AESA system 10. In addition, more surface area on the top face of the printed circuit board 16 may be dedicated to the elements 18.

To that end, each integrated circuit 14 preferably operates on at least one element 18 in the array. For example, one integrated circuit 14 can operate on two or four different elements 18. Of course, those skilled in the art can adjust the number of elements 18 sharing an integrated circuit 14 based upon the application. For example, a single integrated circuit 14 can control two elements 18, three elements 18, five elements 18, six elements 18, seven elements 18, eight elements 18, etc., or some range of elements 18. Sharing the integrated circuits 14 between multiple elements 18 in this manner reduces the required total number of integrated circuits 14, correspondingly reducing the required size of the printed circuit board 16.

As noted above, the dual-mode elements 18 may operate in a transmit mode, or a receive mode. To that end, the integrated circuits 14 may generate time division diplex or duplex waveforms so that a single aperture or phased array 10A can be used for both transmitting and receiving. In a similar manner, some embodiments may eliminate a commonly included transmit/ receive switch in the side arms (discussed below with regard to Figure 5) of the integrated circuit 14. Instead, such embodiments may duplex at the element 18. This process can be performed by isolating one of the elements 18 between transmit and receive by an orthogonal feed connection.

RF interconnect and/ or beamforming lines 26 electrically connect the integrated circuits 14 to their respective elements 18. To further minimize the feed loss, illustrative embodiments mount the integrated circuits 14 as close to their respective elements 18 as possible. Specifically, this close proximity preferably reduces RF interconnect line lengths, reducing the feed loss. To that end, each integrated circuit 14 preferably is packaged either in a flip-chipped configuration using wafer level chip scale packaging (WLCSP), or a traditional package, such as quad flat no-leads package (QFN package). While other types of flip-chip packaging may suffice, WLCSP techniques are preferred to minimize real estate on the substrate 16.

In addition to reducing feed loss, using WLCSP techniques reduces the overall footprint of the integrated circuits 14, enabling them to be mounted on the top face (or the reverse face) of the printed circuit board 16 with the elements 18— providing more surface area for the elements 18.

It should be reiterated that although Figures 3A and 3B (and other figures) show the AESA system 10 with some specificity (e.g., the layout of the elements 18 and integrated circuits 14), those skilled in the art may apply illustrative embodiments to other implementations. For example, as noted above, each integrated circuit 14 can connect to more or fewer elements 18, or the lattice configuration can be different. Accordingly, discussion of the specific

configuration of the AESA system 10 of Figure 3A (and other figures) is for convenience only and not intended to limit all embodiments.

Figure 4 schematically shows a cross-sectional view of the layout of components on the laminated printed circuit board 16 of 3A to highlight the flip- chip mounting of its integrated circuits 14. The integrated circuit 14 in this drawing intentionally is enlarged to show details of a flip-chip mounting technique. Unlike techniques that permit input/ output ("1/ O") only on the edge of the integrated circuit 14, flip-chip mounting permits I/O on interior portions of the integrated circuit 14.

As shown, the integrated circuit 14 has a plurality of pads 28 aligned with a plurality of corresponding pads 28 on the printed circuit board 16. These opposing pads 28 on the integrated circuit 14 and the printed circuit board 16 may be considered to form pairs of pads 28. Solder 30 (e.g., solder balls) electrically connects each the pads in corresponding pairs of pads 28.

Interconnect lines, traces, and other electrical interconnects on/ in the printed circuit board 16 (e.g., lines 26) thus permit the integrated circuit 14 to

communicate with other elements 18 through this electrical interface.

The embodiment shown in Figure 4 forms a space or void (identified by reference number "32") between the bottom of the integrated circuit 14 (from the perspective of this drawing) and the top surface of the printed circuit board 16. This space 32 may remain an open void— containing no material. Some embodiments may take advantage of this extra space 32 to add further

components, such as additional circuit elements, without requiring more circuit board space. Alternatively, this space 32 may contain fill material (not shown) for further mechanical stability and thermal management of the integrated circuit 14.

Other embodiments, however, still may use similar integrated circuits 14, but not use flip-chip mounting techniques. Instead, other mounting techniques may couple the integrated circuits 14 with the substrate 16. Among other things, those techniques may incorporate surface mounting, or wirebond mounting with the integrated circuit 14 rotated 180 degrees from the orientation of Figure 4. Accordingly, discussion of flip-chip mounting techniques is but one of a variety of different techniques that may be used with various embodiments of the invention.

Figure 5 schematically shows details of a receive beamforming IC 14 in accordance with illustrative embodiments of the invention. As shown, the receive IC 14 has four channels 34 that each receives a signal from a satellite 12 via one of Elements 1-4. Those channels 34 combine their signals to produce a single output signal at a common receive output/ interface 36. To that end, each channel 34 has a vertical polarization ("V-pole") receive branch 38 and a horizontal polarization ("H-pole") receive branch 38. Both of these branches 38 in a single channel 34 preferably is logically spaced about 90 degrees apart from one another. For example, one of the branches 38 may connect with the vertical edge of a given rectangular element 18, while the other branch 38 may connect with the horizontal edge of the same element 18 as shown in Figure 3C.

Both the vertical and horizontal branches 38 of a single channel 34 preferably have the same circuit elements in their respective pipelines.

Specifically, each branch 38 has a low noise amplifier 40 to amplify the incoming signal, the phase shifter 42 to shift the signal, and a pair of attenuators 44 for selectively attenuating the signal. The attenuator 44 adjusts to appropriately attenuate the signal as desired for a given application and is used primarily for beamforming purposes. In addition, the attenuator 44 also may be partly used for process and temperature corrections. Among other things, the beamforming IC 14 also may include other functional blocks, such as those for array tapering for sidelobe control, beam broadening for covering more area include for search and seek of target communication device on the other side, temperature compensation, polarization control, etc.

The two branches 38 of each channel 34 preferably are combined at a combining node 64, and then again combined with the signal(s) of another adjacent channel combining node 64. All of the channels 34 in the example combine at a central combining node 64 and direct their signals through an output path 46 to the receive common output interface/ pad 36. This output path 46 optionally has additional attenuators 44, an amplifier 40, and a user/ customer controlled attenuator 50 to produce a single combined signal from all of the channels 34, as well as an assortment of other amplifiers 40 (all amplifiers generically identified by reference number "40" for simplicity) used for optimizing noise figure and power dissipation of the IC 14. The circuitry in these channels 34 and the output path 46 may be referred to as "RF circuitry."

The left middle of the drawing also shows digital circuitry 52 for controlling the operation of the various components within the IC 14. For example, the digital circuitry 52 may include an input to receive an input voltage (e.g., 1.2, 1.5, or 1.8 volts), logic and control memories to store and manage data, temperature sensors, and the noted serial/ parallel port interface ("SPI"). Those skilled in the art can have other digital control circuitry and thus, discussion of specific digital control circuitry is for exemplary purposes only.

Figure 6 schematically shows details of a transmit beamforming IC 14 in accordance with illustrative embodiments of the invention. The layout of this integrated circuit 14 is similar to that of the receive beamforming IC 14, except it is directed to signals (transmit signals) forwarded in the opposite direction. Accordingly, the transmit IC 14 has a common input 54 (a common interface 54) for receiving a signal to be transmitted, and the series of distribution nodes 64 that distribute the signal between the four different channels 34 and, ultimately, the two branches 38 of each of the four channels 34.

In a manner similar to the receive IC 14, each branch 38 of the channel 34 has amplification (e.g., the "buffer 56") phase shifters 42, and attenuators 44. In illustrative embodiments, this transmit IC 14 also has monitoring circuitry (not shown) in each channel 34 or branch 38. Specifically, this monitoring circuitry ensures that a given element 18 is operational and meeting minimum power thresholds during operation. Alternative embodiments also have similar monitoring circuitry on the receive beamforming ICs 14.

It should be noted that the specific values in the figures are illustrative of certain examples and not requirements of various embodiments. Those skilled in the art can select the precise values based upon their intended applications. Prior art beamforming ICs known to the inventors typically operate at relatively higher RF power values, such as 14 dBm (absolute power level measured in decibels and referenced to 1 milliwatt). Those skilled in the art seem to prefer operating at such higher values because it obviates the need for a high number of elements 18 for beam transmission. Instead, fewer elements 18 are required to produce what is believed to be a comparably functional beam. As such, the size of the AESA system 10 beneficially can be reduced.

Despite this teaching, the inventors recognized that operating the beamforming IC 14 at higher power values for satellite transmission purposes had a negative effect— it can cause the resulting transmitted beam to interfere with the neighboring satellite 12. Accordingly, contrary to the conventional wisdom, the inventors recognized that, despite typically requiring more transmission elements 18, operating the beamforming IC 14 at a lower power produced a better, more controllable signal.

Illustrative embodiments therefore operate at lower RF power values than those in the prior art (e.g., below 14 dBm). In particular, the inventors recognized that the transmit IC 14 may operate at values at or below 10 dBm. For example, the output RF power may have a PldB value (the measurement of output power which refers to ldB compression from expected linear value) of between 6 dBm and 9.9 dBm— at or under 10 dBm also is sufficient. As noted, this lower power value enables a high number of elements 18 to meet critical system requirement, such as efficiency, radiation pattern, array size, and emitted radiated power.

For example, the RF power may have a value between X dBm and Y dBm, where X is between 0-9.7 and Y is between 0.1-9.8, and X<Y for the selected values of X and Y. Some examples of such values may be within these one or more of the below ranges: 4-9 dBm, 4-8 dBm, 4-7 dBm, 4-6 dBm, 4-5 dBm. 4-10 dBm and -3 to 4 dBm also are additional ranges that should provide sufficient results in certain instances.

Rather than simply running at lower power (e.g., by reducing the input RF power level to a location 54 of Figure 6), the same beamforming ICs that are made to operate at high RF power values (e.g., PldB of 14 dBm and above), some embodiments configure the beamforming IC 14 to operate at such lower RF power values by reducing the maximum available RF power from the IC. This illustrative configuration saves energy by reducing the DC power requirements of the beamforming IC 14 and the requirements that otherwise may be necessary and/ or useful in a high RF power beamforming IC 14. For example, among other things, the beamforming IC 14 preferably is configured to operate at a quiescent current that, when receiving an energizing signal via a power input port, maintains the operating power within the desired range (e.g., 10 dBm or below). In addition, those skilled in the art preferably configure the load impedance, buffers 56, amplifiers 40, phase shifters 42, and other circuit elements to operate using this lower RF power operation.

Figure 7 shows a process of operating the beamforming IC 14 in a lower RF power mode as discussed above. The process begins at 700, which receives an energizing DC signal though its power input pad 28. This port may be similar to that shown in Figure 10 (discussed below) as an analog supply port. As noted herein, some embodiments may have different supply ports to receive energizing signals of different magnitudes. Receipt of this energizing signal energizes the IC 14 (step 702), causing the IC 14 to operate at a quiescent current that ensures the configured lower power (step 704). For example, the quiescent current may be configured to be between about 41 and 67 milliamps per channel (e.g., 50 milliamps) from a 1.2V supply upon receipt of a lower value energizing current and/ or voltage signal. This example thus yields a total quiescent DC power of about 50 to 80 milliwatts per channel. These values are expected to improve with future efficiency improvements. Accordingly, those in the art may see quiescent currents ranging from lower values, such as 30 or 35 milliamps to 70 milliamps per channel.

The inventors also recognized that they could optimize power

consumption, in certain circumstances, by selectively enabling/ disabling certain channels 34 of one or more beamforming ICs 14 in the AESA system 10. For example, less power may be sufficient, and even preferred from a performance standpoint, when the AESA system 10 is relatively close to a specific target.

Alternatively, more power may be desired to reach a more remote target. The inventors recognized that the ability to optimize the beamforming IC 14 performance based upon that or a number of other selected system

characteristics may be desirable— effectuating certain functions. To that end, as schematically shown in the beamforming systems of Figures 8A and 8B, the beamforming IC 14 may have a channel controller 62, operatively coupled with the plurality of transmit channels 34, to selectively disable and/ or enable one or more channels 34 of the integrated circuit 14 before and/ or during transmission or receipt of a beam.

In a similar manner, the inventors recognized that selectively energizing certain channels 34 and thus, their functional elements 18, provides flexibility in controlling the shape, magnitude, polarization, or phase of a transmitted or received beam— another system function. For example, illustrative embodiments may have a channel controller 62 that can energize a first subset of elements 18 if a first beam shape is needed, and a second subset of elements 18 if a different beam shape is needed. In fact, many different subsets/ combinations of elements 18 may be configured for many different beam shapes and polarization control. This information may be stored in memory, such as in a look up table (LUT), which the controller accesses to shape a beam.

Those skilled in the art may control the system, whether it is the AESA system 10, the beamforming integrated circuit 14, or both, to control a wide variety of other functions. For example, the channel controller 62 may generate commands to selectively turn on and off one or more subsets of the channels 34 to enable the beamforming integrated circuit 14 to distribute and/ or combine signals from different beamforming integrated circuits 14 in an AESA system 10 (discussed herein). As another example, each of the channels 34 of a single eight- channel beamforming integrated circuit 14 may be powered down

independently if only one polarization is needed (e.g., if four channels 34 couple with vertical pads 28 and four channels 34 couple with horizontal pads 28). In that case, for example, four out of the eight channels 34 and their elements 18 may be powered down to mitigate unnecessary power dissipation.

As shown in Figure 8B, the controller may be integrated into one or more of the plurality of beamforming integrated circuits 14— i.e., within the unitary body of one or more beamforming integrated circuits 14. Alternatively, as shown in Figure 8A, the channel controller 62 may be a component or integrated circuity that is separate from the beamforming integrated circuit 14. In that case, the channel controller 62 may be in its own stand-alone integrated circuit. As another example, the channel controller 62 can be distributed across a number of different devices, including on some beamforming integrated circuits 14, on other integrated circuits (e.g., on an application specific integrated circuit) and/ or a microprocessor executing code.

Alternative embodiments may enable portions (e.g.., certain branches 38) of the channels 34. Consider, for example, Figures 5 and 6, in which a

beamforming integrated circuit 14 has channels 34 that each have multiple branches 38 with different polarizations. In that case, the channel controller 62 may selectively enable branches 38 of all channels 34 having a certain

polarization (e.g., all horizontally polarized branches 38 or all vertically polarized branches 38), or certain branches 38 for some other purpose.

Figure 9 shows a process for controlling the system function using this selective channel energization technique. The process begins at step 900, which energizes the beamforming integrated circuit 14 in a conventional manner (e.g., applying turn-on power). Then, at step 902, the controller determines the desired system function, such as controlling the shape of the beam, polarization, polarization purity, side-lobes, or any of the noted desired system functions discussed above (among other things). Next, during transmission or receipt, or before transmission or receipt, Step 904 selectively turns on/ off sets of channels 34 and/ or branches 38.

Figure 10 schematically shows a plan view of interfaces 28 on an interface surface of a beamforming IC 14 in accordance with illustrative embodiments of the invention. In preferred embodiments, the interfaces are implemented as a plurality of pads 28 on the bottom side of a flip-chip beamforming IC 14. Each of the pads 28 are clearly marked schematically as squares and as having one of a plurality of specific functions. Those functions are identified as follows:

• Analog Supply X: input supply voltage having a value of X volts

• Analog Supply Y: input supply voltage having a value of Y volts, where Y volts is different from X volts

• GND: a standard ground

• GND-RF: ground for the RF pads

• RF: RF input (for receive beamforming ICs 14)/ RF output (for transmit beamforming ICs 14)

• Digital: digital interfaces for controlling the beamforming IC 14. As noted and shown, this design permits two different types of analog supply interfaces for receiving two different supply voltages in a single beamforming IC 14. Specifically, one set of the supply interfaces (e.g., Analog Supply X) can receive a powering signal having a first voltage, while a second set of supply interfaces (e.g., Analog Supply Y) can receive a powering signal having a second (different or same) voltage. The inventors recognized that this design can improve the flexibility of the beamforming IC 14. Specifically, this design enables optimization of the supply voltage for sensitive blocks with the extra supply voltage interfaces (e.g., the Analog Supply X interfaces at the corners of the array of power interfaces). This design also may optimize power dissipation of the low noise amplifier 40 in the receive beamforming IC 14, or the power amplifier 40 in the transmit beamforming IC 14. While the two different analog supply are shown, in certain application they can be connected and thus, a single supply can be used.

In illustrative embodiments of the invention, the analog supply pads 28 are concentrated in an inner region of the IC surface (i.e., the surface to be flip- chip mounted on the substrate 16). Figure 10, for example, shows an incomplete 5 X 3 array/ set of fourteen analog supply pads 28 in that inner region. Of note is the absence of the center pad 28, which may be omitted or added in other embodiments. This high-current DC injection area in the center of the chip may minimize the complexity of final application board design. Indeed, various embodiments may have more or fewer than fourteen analog supply pads 28. Accordingly, like other features shown in this figure, specific locations and numbers of certain elements 18 are illustrative and not intended to limit all embodiments. A plurality of other interface pads 28 circumscribe this inner set of supply pads 28. These other interface pads 28 may be any of the other pad types listed above. In illustrative embodiments, the analog supply pads 28 are adjacent only to GND pads 28. Specifically, no other pads 28 are between two adjacent pads 28. It should be pointed out that, as shown in the figures, circumscribing does not imply that there is a continuous barrier of interface pads 28 around the inner set of pads 28.

Certain design constraints of AESA systems 10 have a spacing

requirement between pads 28. For example, for certain AESA applications, wafer level chip-scale packages are required to space their pads 28 about 400 microns apart. This relatively large pad distance is difficult to attain, however, with such small package designs.

To obviate this problem, illustrative embodiments position some or all of the RF pads 28 are along the edge of the IC 14 and preferably have GND-RF pads 28 adjacent to two of its opposing sides. As shown, those two GND-RF pads 28 also preferably are positioned along the edge. To comply with current design requirements, the RF pads 28 may be spaced about 400 microns from their adjacent GND-RF pads 28. Some embodiments, however, may space the pads 28 between 300-400 microns apart as tighter technology rules perhaps become feasible. The inventors recognized that using a configuration such as this further mitigates noise and cross-talk between RF interfaces/pads 28 at high frequencies, such as in the microwave and millimeter-wave frequencies generally greater than about 10 GHz. This design provides effective RF isolation with its nine RF interface pads 28— e.g., eight for the V and H branches 38 of the four channels 34, and one common RF interface as shown in Figures 5 and 6.

After various failed attempts, the inventors recognized that moving the power pads 28 radially inwardly, as shown in Figure 10, facilitated their ability to meet the spacing requirements and provide the necessary isolation. As shown, some embodiments position a GND pad 28 adjacent to the other, more interior side of the RF pad 28. Also as shown, the digital pads 28 too are adjacent to the edge of the IC 14 for easier access and to mitigate signal loss.

Figure 11 schematically shows a layout of beamforming integrated circuits

14 across an AESA substrate 16 in accordance with illustrative embodiments of the invention. For simplicity, this figure shows just a portion of the layout of a complete AESA system 10. This figure schematically shows a plurality of beamforming ICs 14, divider/ combiner nodes, and the electrical connection network for transmitting or receiving signals. This figure of the AESA system 10 may be considered to show a 4 X 4 array of IC sets. For discussion purposes, the top left set of ICs 14 has a box around it. In this embodiment, the four circles at the corners of the square are beamforming ICs 14 that each are connected to four elements 18 (not shown in this figure) by beamforming lines 26. The three circles of the middle, labelled with reference number "64," thus act as

dividers/ combiners depending on whether the IC 14 is a transmit or receive IC 14. Such divider/ combiners are also referred to as "Wilkinsons."

Node elements 64 and 66 (discussed in detail below) electrically couple signals of the various beamforming IC sets. Prior art AESA systems known to the inventors typically used different integrated circuits that are customized for this function, but different from the beamforming ICs 14. Although those skilled in the art have found that such a scheme may work satisfactorily, the inventors recognized that the different design considerations of such a customized IC can differ from those required to produce or receive a well-defined beam. After experimentation, the inventors discovered that using node devices 64 that are substantially identical to the beamforming ICs 14 in the sets provided more well- defined beams. Accordingly, in illustrative embodiments of the invention, this AESA system 10 uses other beamforming ICs 14 to act as nodes ("driver ICs 64", "node ICs 66", or "distribution ICs 66"— each of which are beamforming ICs 14) that distribute or combine the signals from the various sets of beamforming ICs 14. Transmission lines 26 electrically couple each set with a node IC 66 (i.e., a like beamforming IC) that combines (if a receive AESA system 10) or distributes (if a transmit AESA system 10) signals from/ to the sets of beamforming ICs 14.

Specifically, as shown in Figure 11, the node ICs 64 are electrically coupled between the noted beamforming IC sets. For example, transmission lines 26 (e.g., traces, wires, etc.) of some kind may electrically couple a node IC 66 between 1) other node ICs 64, a beamforming IC 14 in a set, or Wilkinson and 2) other node ICs 64, a beamforming IC 14 in a set, or Wilkinson. As shown in Figure 11, a single node IC 66 can electrically couple multiple sets of beamforming ICs 14 in a hierarchical manner to scale the array to a large size.

Thus, for the left top box in Figure 11, the beamforming ICs 14 in the receive mode combines signals using a combining node 64, such as a Wilkinson, and they again combine by another layer of Wilkinson. At that point, the node IC 66 further combines the other beamforming ICs 14 that come together. The node IC 66 position is carefully chosen to maintain a high fidelity of signal in terms of noise and interference. The same process happens in the transmit mode, but in reverse. Those skilled in the art may use the node ICs 66 as a trade-off of noise, gain, and linearity. With this design, each node IC 66 may have

substantially the identical functionality to those of the other beamforming ICs 14 in the sets— in this example, the same as the four beamforming ICs 14 in each set.

For example, among other things, the node ICs 64 and other beamforming

ICs 14 may:

• be formed using the same processes, • in the same fabrication batch,

• be the same model/ part number,

• be a different version of the same model/ part number,

• be produced with substantially the same specifications and/ or

performance requirements,

• have the same number and types of interfaces,

• have interfaces at the same locations, and/ or

• have substantially the same functional elements/blocks. Accordingly, the node ICs 64 have beamforming components, such as phase shifters 42, amplifiers 40, that are in the other beamforming ICs 14 of the AESA system 10. The node ICs 64 of this embodiment thus should have the same circuit characteristics as those of the other beamforming ICs 14. In other words, the node ICs 64 in this embodiment may be interchangeable with the other beamforming ICs 14. As with the multi-channel, multi-branch embodiments discussed herein, the node ICs 64 correspondingly preferably have multiple channels 34 that each have multiple branches 38 if used in an AESA system 10 with these beamforming ICs 14. Some embodiments further condition the signals they receive, such as by amplifying, attenuating, buffering, and/ or phase shifting before forwarding them to the next component in the AESA system 10.

When implemented as a multi-channel beamforming IC 14, some embodiments of the node IC 66 may enable fewer than all channels 34 when acting as node ICs 64 and thus, not use all signal pads/interfaces 28. This is similar to the embodiment in which fewer than all channels 34 and/ or branches 38 are used. The interfaces 28 of these unused or disabled channels 34

accordingly may be considered to be "electrically uncoupled," saving power. Indeed, although some quiescent or other current may be transmitted through such channels 34, they still are considered to be electrically uncoupled because they are not used for beamforming or signal distribution/ combination. The quiescent current also may be switched off for uncoupled paths, thus saving power. Figure 11, for example, shows node ICs 64 that electrically couple with four sets of beamforming nodes. Thus, such node ICs 64 may use only four interfaces/ pads 28 and not use the other interfaces/pads 28.

Within the sets of beamforming ICs 14, rather than using Wilkinsons, alternative embodiments use like-type beamforming ICs 14 to

distribute/ combine signals. Accordingly, as suggested above, in addition to the node ICs 64 discussed above, the nodes receiving or distributing signals within the beamforming IC sets also may include node ICs 64.

In some embodiments, although substantially the same devices, different node ICs 64 in a single AESA system 10 may be configured to apply its functional components in different manners. For example, a node IC 66 receiving signals from four sets of beamforming ICs 14 may amplify signals a first amount, while a node IC 66 receiving signals from sixteen sets of combined beamforming ICs 14 may amplify signals by a second amount, or not at all.

Rather than using only the node ICs 64, this network also may use other conventional dividers/ combiners at other locations. Some embodiments, however, may use the node ICs 64 at those locations. Those skilled in the art can select the appropriate number and configurations of the node ICs 64 versus Wilkinsons.

Figure 12 shows an example of digital transactions that may be used in accordance with illustrative embodiments of the invention. Specifically, in illustrative embodiments, the digital control circuitry (noted above) controls the operation of the beamforming IC 14. Among other things, illustrative

embodiments may have a five wire serial interface supporting daisy chain and parallel data write programmable registers. Those registers may hold control and compensation values for the analog/ RF circuits on the beamforming IC 14.

Other embodiments may have more wires (e.g., 6, 7, 8, or 9 wires) or fewer wires (e.g., 4, 3, or 2) at the serial interface

The beamforming IC 14 may have fast memory capability. To that end, in illustrative embodiments, the IC 14 may have fast beam steering attributes because there is no need for transmit/ receive switching functionality. Instead, there are eight channels 34 instead of four, and FBS memory may be combined into 512 states. Each state can be 48 bits wide (i.e., 6 bit phase information for 8 channels 34). The IC 14 also may have 3D beam steering capability. For example, it may have 8 x (4-bit amp per quad) + 3-bit amp in common + 8 element-disable bits = 43-bits per state. It further may use 32 sets of 48 bits. As noted above, illustrative embodiments also may compensate for performance at different temperatures.

The beamforming IS also may have:

• one-time programmable (OTP) non-volatile memory for calibration values,

• daisy chain read and write support, and/ or

• asynchronous latching of power-detector data to minimize RF

interference in transmit mode.

With regard to Figure 12, illustrative embodiments support one or more of series, parallel, hybrid transactions. The leading control words may determine the type of transaction. Specifically:

• Serial: The data shifts through the IC's shift registers serially using serial parallel interface ("SPI") as input or output (SPI/SDI or SPI/_SDO). • Hybrid: All selected ICs 14 receive the control word in parallel, and data shifts serially. They may use SPI_PDI for the control word and SPI_SDI for the data.

• Parallel: All selected ICs 14 receive data simultaneously on SPLPDI.

• Fast: Short, parallel writes targeting specific registers using

SPLPDI.

Illustrative embodiments of the beamforming ICs 14 produce and track any of a variety of polarization schemes, such as circular polarization, elliptical polarization, or linear polarization. For example, satellites 12 typically use circular polarization for general insensitivity to relative motion. Such a scheme can be produced on either/ both the receive or transmit ICs 14.

Figure 13 schematically demonstrates such a scheme, configured in accordance with one embodiment, with a single channel 34 and a simplified version of its two branches 38 connected with a single element 18. As shown, the beamforming IC 14 has a combiner (shown with the division symbol) to receive the shifted first and second signals, from two different branches 38, to produce a combined signal. The branches 38 respectively have first and second amplifiers 40, and first and second phase shifters 42 with related phase shifts. The phase shifters 42 are generically denoted as F_1 and F_2.

The first and second phase shifters 42 are selectable so that the combined signal has one of a plurality of different selectable polarizations. Specifically, the table to the right of the circuit shows how each phase shifter 42 sets its phase to produce different polarizations. Both use a base phase of Q. Thus, to obtain right hand elliptic polarization, for example, F_1 is set to Q and F_2 is set to Q + 90 degrees. The other three listed options are self-explanatory to obtain left hand elliptic polarization, slant linear-H, and slant linear-V. Indeed, those skilled in the art can modify the circuit and parameters to obtain other arbitrary

polarizations required for a given application. Accordingly, discussion of the various examples of Figure 13 is not intended to limit other embodiments.

Although the above discussion discloses various exemplary embodiments of the invention, it should be apparent that those skilled in the art can make various modifications that will achieve some of the advantages of the invention without departing from the true scope of the invention.