This paper describes a novel multi-metal layered interconnect-based heterogeneous integration approach for developing a reworkable superconducting qubit package. Various microbump options, including gold, tin, indium, and tin indium, were used to achieve the desired flip-chip configurations. As a case study, we demonstrate a reworkable cryogenic superconducting qubit package capable of interconnecting up to 32 microwave lines. The flip-chip package configurations show low (below 30 dB @ RT) nearest-neighbor crosstalk up to 10 GHz. Initial qubit measurements at low temperatures (~10 mK) show qubit lifetime T 1 > 100 μs (Q > 2M), which is comparable to the planar versions measured in our standard Al wirebonded package. Keywords—qubit, heterogeneous integration, interconnect, flip-chip, crosstalk.

MIT Lincoln Laboratory is developing a planar V-band phased array antenna. The radiator is required to provide 15% bandwidth with 30° elevation and 50° azimuth scanning capability with vertical polarization. Due to the high level of integration of the radiator and the RF front-end, the goal for the antenna array is to be integrated on printed circuit board (PCB) technology with the T/R module mounted on the opposing side. This design results in a very tightly integrated radiator and RF distribution network in a multi-layer PCB stack up that utilizes Ormet paste technology. A detailed description of the antenna array and RF feed network will be reviewed.

This paper is an update on our development of a Digital Polarimetric Phased Array Radar (DPPAR), an ongoing effort sponsored by the National Oceanic and Atmospheric Administration (NOAA). DPPAR leverages commercial-off-the-shelf microwave processing technology to meet NOAA's future meteorological radar needs for rapid, volumetric scanning and superior data quality. The DPPAR prototype is a digital-at-every-element phased array aperture, comprised of two identical panels, each containing 64 dual-polarized elements operating at S-band. The current state of development, preliminary test results and future efforts will be discussed.

Quantum processing has the potential to transform the computing landscape by enabling efficient solutions to problems that are intractable using classical processors. The field was sparked by a suggestion from physicist Richard Feynman in 1981 that a controllable quantum system can be used to simulate other quantum systems, such as the energy band structure of complex materials or the chemical reaction rates of intricate molecules. In the 1990s, interest in quantum computing grew rapidly with the introduction of the first quantum "killer app"-the potential of a large-scale quantum processor to break certain types of public encryption schemes [1]. Recently, there has been growing consensus that myriad other fields besides data security could be impacted by the development of a quantum processor, including machine learning [2], many optimization problems [3], and Feynman's original idea of the simulation of materials properties [4]. In recent years, the field has progressed rapidly, but many technical challenges must be overcome before a large-scale quantum processor can be built. This article focuses on the development of packaging for solid-state qubits and the use of 3D integration to address this challenge.

MIT Lincoln Laboratory (MIT LL) has been working in support of the Multifunction Phased Array Radar (MPAR) program to develop low-cost phased array radar. MIT LL along with MACOM has developed an S-band 64-element dual-polarization phased array panel with 6 W radiated power per element per polarization. The third generation of this panel was used to build a 76-panel fully polarimetric AESA radar, the MPAR Advanced Technology Demonstrator (ATD). Recently characterized at MIT LL's RF Test Facility, the ATD has EIRP of 85 dBW, 40 dB boresite directivity, and less than 0.04° beam steering error. The ATD was installed at the National Weather Radar Testbed (NWRT) at the National Severe Storms Laboratory (NSSL) in 2018. This paper summarizes nearfield chamber test results, installation, and calibration of the 76-panel MPAR ATD.

Since 2007, MIT Lincoln Laboratory (LL) has been developing low-cost phased array panel technology in support of the Multifunction Phased Array Radar (MPAR) program. The MPAR program targeted the development of affordable active electronically scanned arrays (AESAs) for the civilian applications of aircraft surveillance and weather forecasting. Over the last decade, in a teaming with MACOM, Lincoln Laboratory has developed an S-band, 64-element dual-polarization (pol) panel with a peak radiated power of 6W per element per pol. The 3 rd generation (Gen3) panel will be used to populate a 4m-diamter, 76-panel fully polarimetric AESA radar. This radar, the MPAR Advanced Technology Demonstrator (ATD), will be fielded at the National Weather Radar Testbed (NWRT) at the National Severe Storm Laboratory (NSSL) in Norman, OK, with IOC scheduled for 2018. This paper summarizes the development of the MPAR panels, the ATD, and the nearfield characterization of the ATD scheduled for the latter half of 2017.

MACOM designed the initial radar panels for the next generation surveillance radar with limited funds, with the philosophy that the initial design would be kept as simple as possible and that incremental improvements would be made as the program progressed, with the intent of having a tile assembly that is easy to manufacture by the first build of a larger radar (approximately 80 panels). The design is now being updated for an 80 panel order with the goal of optimizing the design electrically, for assembly and for test. This paper will discuss both the design, assembly, packaging, and test updates that are being made to have a board and board assembly that is easy to manufacture and test, with the goal of keeping cost as low as possible. These techniques will not only be used for the MPAR tiles, but also for tiles that are currently being developed for other programs.

Phased array technology has been evolving steadily with advances in solid-state microwave integrated circuits, analysis and design tools, and reliable fabrication practices. With significant government investments, the technologies have matured to a point where phased arrays are widely used in military systems. Next-generation phased arrays will employ high levels of digitization, which enables a wide range of improvements in capability and performance. Digital arrays leverage the rapid commercial evolution of digital processor technology. The cost of phased arrays can be minimized by utilizing high-volume commercial microwave manufacturing and packaging techniques. Dramatic cost reductions are achieved by employing a tile array architecture, which greatly reduces the number of printed circuit boards and connectors in the array.

MIT Lincoln Laboratory is working towards the development of a tileable radar panel to satisfy multimission needs. A combination of custom and commercial off-the-shelf (COTS) Monolithic Microwave Integrated Circuits (MMICs) have been developed and/or employed to achieve the required system functionality. The integrated circuits (ICs) are integrated into a low cost T/R module compatible with commercial printed circuit board (PCB) manufacturing. Sixty-four of the transmit/receive (T/R) modules are integrated onto the aperture PCB in an 8 × 8 lattice. In addition to the T/R elements, the aperture PCB incorporates transmit and receive beamformers, power and logic distribution, and radiating elements. The aperture PCB is coupled with a backplane PCB to form a panel, the line replaceable unit (LRU) for the multifunction phased array radar (MPAR) initiative. This report summarizes the evaluation of the second iteration LRU aperture PCB and T/R element. Support fixturing was developed and paired with the panel to enable backplane functionality sufficient to support the test objectives.

MIT Lincoln Laboratory (MIT LL), in an effort sponsored by the National Center of Atmospheric Research (NCAR), has engaged in the development of C-Band active element phased array front-end hardware for a polarimetric radar application. This polarimetric active element scanning array (AESA) radar, when fully developed, would be deployed on a C-130 for use in Hurricane Hunter-like missions. The combination of mission and platform imposes requirements on the RF hardware that are often in conflict. These specifications include minimum range and resolution, maximum prime power, and a challenging cross-polarization isolation requirement. The RF hardware developed included a dual polarization (pol) radiator test panel, an alternating transmit simultaneous receive (ATSR) transmit/receive (T/R) switch designed and manufactured by M/A-COM Technical Solutions (MTS), a three channel T/R multichip module (MCM), and a four-pack T/R module assembly. This paper describes the mission and platform requirements, presents a notional design for the phased array aperture, discusses the design trades, and provides an overview of the design and performance of the radiator test panel, the MCM and the four-pack T/R module. This work borrowed heavily in terms of materials, technologies, and lessons learned acquired over the past five years from the MPAR Panel [1] development efforts of MIT LL and MTS co-sponsored by the Federal Aviation Administration (FAA), the Air Force, and the National Severe Storms Laboratory.

This paper describes a method to answer the following questions: can several of the elements of a phased array be employed as auxiliary (AUX) elements and how can the phase of each be adjusted so that the (1) cross-polarization (cross-pol) isolation is minimized to 40 dB, (2) the sidelobe levels of the main lobe are minimally impacted, and (3) the width and height of the main lobe are minimally impacted? This calibration work is being completed as one component of Lincoln Laboratory's effort within the multifunction phased array radar (MPAR) initiative. Devoting a few of the elements to serve as the AUX channels to specifically operate to mitigate the effects of the cross-pol influence, the distributed sidelobe levels will not suffer much impact; yet, the impact of the AUX elements will have deepened the cross-pol isolation at the peak of the co-polar beam can occur because the AUX elements can achieve a high degree of narrowband angular resolution.

This paper describes a semiautonomous approach to calibrate a phased array system, with particular use on an S-band aperture that is being developed at MIT Lincoln Laboratory. Each element of the array is controlled by an independent digital phase shifter, whose control signal may be uniquely defined. As active electronically steerable arrays (AESAs) continually evolve towards mostly digital paradigms that will support real-time computing, as opposed to look-up table approaches, then adaptive calibration approaches may be pursued for maximum AESA performance. This calibration work is being completed as one component of Lincoln Laboratory's effort within the multifunction phased array radar (MPAR) initiative.