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This letter provides an overview of the metal-embedded chiplet assembly for microwave integrated circuits (MECAMICs) technology. MECAMIC is a 2.5-D wafer-level packaging approach that provides seamless heterogeneous integration capabilities of compound semiconductor transistors (e.g., GaN HEMTs) with passive components and interconnects using a backside metal embedding process. The chiplets are embedded in through-interposer cavities, and the backside metallization locks the chiplets into position while providing dc and RF ground for the high-frequency circuits. With this hybrid manufacturing approach, high-performance RF ICs can: 1) be designed using the best transistor technology for the function; 2) be fabricated in short cycle times through hybrid manufacturing; and 3) compete performancewise with monolithic circuits. We demonstrated an $X$ -band power amplifier circuit realized in MECAMIC with a saturated output power of 31 dB and a peak power added efficiency of 54%, which compared favorably to its monolithic GaN monolithic microwave integrated circuit (MMIC) counterpart. The MECAMIC process cycle time was $4.5\times $ faster than the monolithic process.

We report the development of high efficiency Ka-band (33 GHz – 36 GHz) MMIC amplifiers in a highly scaled 40nm HRL’s T4A GaN MMIC process. The reported two stage power amplifiers have peak power added efficiency (PAE) of 58.5% with associated gain of 11.9 dB and associated output power of 24.4 dBm measured at a frequency of 34 GHz in continuous wave (CW) mode. The exceptionally high efficiency of reported MMICs is a result of outstanding device characteristics of highly scaled GaN HEMTs.

This paper describes optically semi-transparent and flexible microstrip interconnects and patch antennas at millimeter wave frequencies. They are realized on a 5-mil thick transparent PET film by patterning honeycomb shape metal grids using a standard lithographic process. Dimensions of the employed metal grids were optimized for low insertion loss and >70% optical transmission at 77 GHz to enable integration into non-conventional surfaces for potential automotive radar applications. The fabricated microstrip lines demonstrate low-loss interconnects with

We report the first demonstration of: 1) wide-wavelength range, infrared transparent conductors (ITCs) made of silver nanowires (Ag NWs), and 2) ITC contact-integrated prototype, InAsSb mid-wavelength IR (MWIR) detectors. The Ag NW-based ITCs show optical transmittance ( $T_{\lambda}$ ) of ∼94% in the 0.9–2.5 μm wavelength range with a sheet resistance ( ${\rm R_{s}}$ ) of 19.1 Ω/□. $T_{\lambda}$ of the Ag NW-ITC decreases slowly with increasing wavelength, resulting in $T_{\lambda}$ ∼92%–87% at 2.5–8 μm (MWIR) and $T_{\lambda}$ ∼87%–82% at 8–15 μm (LWIR). The Ag NW-based ITC makes good ohmic contacts on InAsSb-based MWIR detectors with contact resistance of 85% at 4.25 μm and 150 K. The measured external QE remains at the same high level regardless of detector fill factor. These results indicate that Ag NW-ITCs may enable future pixel scaling for front-side illuminated, high-density-format focal plane arrays without compromising QE, responsivity, and detector performance.

We describe our recent results in developing and maturing small pixel (5μm pitch), high definition (HD) mid-wave infrared (MWIR) detector technology as well as focal-plane-array (FPA) hybrids, and prototype 2.4 Megapixel camera development operating at high temperature with low dark current and high operability. Advances in detector performance over the last several years have enabled III-V high operating temperature (T≥150K), unipolar detectors to emerge as an attractive alternative to HgCdTe detectors. The relative ease of processing the materials into large-format, small-pitch FPAs offers a cost-effective solution for tactical imaging applications in the MWIR band. In addition, small pixel detector technology enables a reduction in size of the system components, from the detector and ROIC chips to the focal length of the optics and lens size, resulting in an overall compactness of the sensor package, cooling and associated electronics. An MBE system has been used to grow antimony-based detector structures with 5.1μm cutoff with low total thickness variation (TTV) across a 3” wafer, in order to realize high interconnect yield for small-pitch FPAs. A unique indium bump scheme is proposed to realize 5μm pitch arrays with high connectivity yield. Several 1kx2k /5μm hybrids have been fabricated using Cyan’s CS3 ROICs with proper backend processing and finally packaged into a portable Dewar camera. The FPA radiometric result is showing low median dark current of 2.3x10 -5 A/cm 2 with > 99.9% operability, and >60% QE (without AR coating).

Barrier detectors based on III-V materials have recently been developed to realize substantial improvements in the performance of mid-wave infrared (MWIR) detectors, enabling FPA performance at high operating temperatures. The relative ease of processing the III-V materials into large-format, small-pitch FPAs offers a cost-effective solution for tactical imaging applications in the MWIR band as an attractive alternative to HgCdTe detectors. In addition, small pixel (5-10μm pitch) detector technology enables a reduction in size of the system components, from the detector and ROIC chips to the focal length of the optics and lens size, resulting in an overall compactness of the sensor package, cooling and associated electronics. To exploit the substantial cost advantages, scalability to larger format (2kx2k/10μm) and superior wafer quality of large-area GaAs substrates, we have fabricated antimony based III-V bulk detectors that were metamorphically grown by MBE on GaAs substrates. The electro-optical characterization of fabricated 2kx2k/10μm FPAs shows low median dark current (3 x 10-5 A/cm2 with λco = 5.11μm or 2.2 x 10-6 A/cm2 with λco = 4.6μm) at 150K, high NEdT operability (3x median value) >99.8% and >60% quantum efficiency (non-ARC). In addition, we report our initial result in developing small pixel (5μm pitch), high definition (HD) MWIR detector technology based on superlattice III-V absorbing layers grown by MBE on GaSb substrates. The FPA radiometric result is showing low median dark current (6.3 x 10-6 A/cm2 at 150K with λco = 5.0μm) with ~50% quantum efficiency (non-ARC), and low NEdT of 20mK (with averaging) at 150K. The detector and FPA test results that validate the viability of Sb-based bulk and superlattice high operating temperature MWIR FPA technology will be discussed during the presentation.

We report very wideband 100 MHz to 1 GHz active circulator with high power operation up to 30 dBm for the first time. In order to achieve broadband high power circulation and isolation, a new architecture is developed using low-loss RF choke concept and it is implemented on alumina substrate with mounted GaN HEMT devices along with other SMTs. The performed test shows minimum 15 to 20 dB isolation up to 30 dBm and 15 dB directivity up to 26 dBm across the band with 2.5~5 dB insertion loss for 15 dB of minimum directivity.

A high azimuth and elevation resolution multiple-input-multiple-output(MIMO) radar prototype with 16 Tx and 16 Rx antenna elements was developed in this work to address the autonomous driving vehicle challenges in complex urban environments. This article describes the technological scope of the developed prototype, details the performance challenges and discusses the system design considerations. The main goal of the developed automotive radar prototype is to achieve a high 2D angular resolution in the presence of a large number of radar echoes while maintaining an industry acceptable antenna aperture size and reasonable cost.