Mismatch Measurement for MIMO mm-Wave Radars via Simple Power Monitors

Hardware imperfections and environmental factors create mismatches between transmit and receive paths. In MIMO mm-Wave radars, determining and eliminating gain and phase mismatches are required to increase the overall accuracy of range and angle of arrival (AoA) estimation. Measurement of mismatches, particularly phase mismatch, requires complex test setups and external equipment, such as a network analyzer. This paper proposes an on-chip (or on-board) measurement method for mm-Wave radars to determine the mismatches using RF power detectors. The proposed method relies on mutual coupling between transmitter and receiver antennas. A detailed mathematical analysis of the proposed method along with boundary conditions is presented. Simulations and hardware measurements using a cascaded mm-Wave radar device shows that the proposed phase mismatch extraction technique provides very accurate results within defined boundary conditions.