19.6 A 60GHz I/Q-Calibrated SSB-Mixer-Based LO with Sub-ns Settling Time and −56dBc Worst-Case Spur Using ILO Filter in 28nm CMOS

Joint communication and radar sensing (JCAS) has been gaining much attention for its efficient use of spectrum, particularly in applications such as autonomous vehicles and 6G systems. Among the various modulation schemes for JCAS, OFDM is favored as it offers robustness against interference in radar sensing and enables high data-rate communication. Additionally, implementing JCAS in the mm-wave band is highly preferred, as it provides the large bandwidth necessary to increase radar resolution and data-rate. However, the wide bandwidth in mm-wave poses a significant challenge for the receiver-end ADC. A promising approach to address this challenge is the stepped-carrier (SC)-OFDM scheme [1], [2], which divides the wide RF bandwidth into smaller, frequency-hopped bands, thereby reducing the ADC bandwidth requirements. Unfortunately, the SC-OFDM imposes stringent requirements on the LO, which must achieve both low jitter and rapid settling during frequency hopping to have sufficient SNR. Specifically, the settling time of the LO must be significantly shorter than the guard interval [2], requiring a settling time much faster than 18ns for the IEEE 802.11ay standard [3].