A 94-GHz High Resolution Radar Using Time Interleaving Active Array in 65-nm CMOS

This work presents a high angular resolution radar system operating at 94 GHz, utilizing a 20-channel receiver (RXs) and a single-channel transmitter (TX) in 65-nm CMOS technology. The receiver consists of five subarray chips and each chip has four receiving channels. Among these five receiving chips, the 4 channels of the first chip are continuously sampled for all chirp intervals and the 4 channels of other four receiver chips are sampled in a time interleaved way at their allocated chirp times. The fully sampled channels process the range-Doppler information with coarse angular information of the targets and provide the phase reference to the time-interleaved RX channels. The time-interleaved massive channels are used to obtain range and high-resolution angular information. This approach allows for processing the information from all 20 RX channels using only eight-channel analog-to-digital converters (ADCs), thereby significantly reducing the cost and complexity associated with a radar system comprising massive RX channels with high scalability. The challenges associated with packaging, antenna integration, and LO distribution in W-band for a massive channel radar system are overcome by a high ratio multiplier design to be driven by a low reference frequency-modulated continuous wave (FMCW) waveform and using an on-chip antenna feeder, facilitating low-loss and compact integration. Experimental results demonstrate that the implemented radar system achieves an angular resolution of 1.74°. These results suggest that a sub-1° super-resolution radar can be designed by incorporating multiple-input multiple-output (MIMO) techniques.