A 77-GHz Hybrid TDM-MIMO Phased-Array Radar With 186-m Detection Range and 3-cm Range Resolution

This article presents a fully integrated 77-GHz hybrid time-division-multiplexing multiple-input–multiple-output (TDM-MIMO) phased-array radar in a 55-nm CMOS process. The system integrates eight independent transmitters (8 × 1 TXs) and two four-channel phased-array receivers (2 × 4 RXs), achieving a 4.76× increase in detection range compared to single-input–single-output (SISO) architecture in long-range radar (LRR) mode and 1.79◦ angular resolution with 16×4 virtual array in short-range radar (SRR) mode. To realize a large chirp bandwidth while maintaining low voltage-controlled oscillator (VCO) gain (KVCO), a zig-zag phase-locked loop (PLL) based frequency-modulated continuous wave (FMCW) generator is proposed, enabling continuous multi-subband chirping. By monitoring the voltage across the capacitance in loop filter (VCAP) for subband switching, the tuning voltage (VTUNE) is configured to the optimal switching voltage, eliminating the frequency ripple (FR) during subband switching. Each TX channel integrates switches to support a flexible number and positioning of 1–8 transmitters in TDM mode. To mitigate the leakage effect caused by variations in amplitude and phase due to the varying number and position of TX on-channels, a receiver architecture with three low noise amplifiers (LNAs) and a 4-bit phase shifter is designed to achieve low noise figure (NF) and high linearity. Furthermore, an I/Q mixer is designed to achieve orthogonal ellipse-overlapping-shape NF and petal-shape linearity over a phase difference range of 0◦–360◦ ∆φleak between the localoscillator (LO) and leakage. The chip achieves a measured maximum chirp bandwidth of 12.6-GHz spanning four zig zag subbands. The root-mean-square (rms) frequency error is 0.0068% at 18.8-MHz/µs chirp rate with 2.5-GHz bandwidth, and 0.3% at 545-MHz/µs chirp rate with 2.65-GHz bandwidth. The eight-channel TX achieves a maximum effective isotropic radiated power (EIRP) of 32 dBm at 78.8 GHz, while the four-channel RX achieves a minimum NF of 16.3 dB at a 2-MHz intermediate frequency (IF). The hybrid radar achieves a detection range of 186 m and a range resolution of 3 cm.