Summary
Interest in wideband Active Electronically Scanned Array AESAs with digital-at-every-element architectures has been increasing over the past decade.
Wideband AESAs are more versatile and robust because they allow for operation at different frequencies, as opposed to narrowband arrays that are tuned for a specific use and frequency.
Digital-at-every-element architectures allow AESAs to perform beamforming in the digital domain, enabling the simultaneous collection of many beams. However, current implementations of wide bandwidth receivers often have limited dynamic range that leave them vulnerable to electronic interference and jamming, particularly in congested RF environments. Further, digital-at-every-element requires filtering at the element level, leaving very little room to integrate conventional filter technologies.
To address the challenges impeding the use of wideband AESAs in congested RF environments, DARPA is executing the COmpact Front-end Filters at the ElEment-level (COFFEE) program. COFFEE aims to develop a new class of integrable, high-frequency RF filters for next-generation wideband arrays.
The COFFEE filter technology will address the combination of size, performance, and reproducibility to enable protection at every element of a wideband AESA. COFFEE aims to build integrable filters that operate over a wide range of frequencies that are also small enough to fit behind each element of the phased array thus making the array more robust and resistant to interference. Key to the program is the development of filter technology that can address all microwave frequencies of a wideband AESA’s bandwidth without sacrificing performance. Further, the target filters must be physically small compared to the element area as the available space for element-level integration decreases significantly as AESA bandwidth increases. Finally, to ensure uniformity the COFFEE filters should be manufacturable with reproducible performance at each of the array elements.
A main focus of the research will be on developing a new class of resonators and integrable microwave filters that address COFFEE’s technical objectives. In addition, research studies into compact mm-wave resonators will be conducted to inform new technical approaches for potential future efforts for integrable mm-wave filters.
COFFEE is a part of DARPA’s Electronics Resurgence Initiative (ERI) – a five-year, $1.5 billion investment in the advancement of the U.S. semiconductor industry. The program addresses a key ERI focus area of revolutionizing communications for the 5G era and beyond.