A 94 GHz 8Tx-16Rx Direct Center-Fed Active Array TD-MIMO FMCW Radar in 28-nm CMOS

This paper introduces a 94 GHz 8Tx-16Rx high-resolution FMCW radar system utilizing single-channel Tx and four-channel Rx chipsets with high-ratio ($\times 24$) frequency multipliers. A robust and compact direct center-fed antenna packaging is developed for scalable massive array implementation. With the proposed packaging without antenna feedline, the active array, formed with antenna-integrated Tx and Rx, can be efficiently arranged into a 2D optimal thinned array to maximize angular resolution. Additionally, a time-domain MIMO architecture with time-interleaved Rx sampling is employed to implement 128 virtual channels, enabling efficient utilization of the radar back-end. Each fabricated antenna-integrated Tx and Rx channel demonstrates 27 dBm EIRP and 42 dB receiver gain, respectively. The radar system achieves high angular resolutions of 1.2° in azimuth and 2.38° in elevation direction.