Co-design of a wideband double-balanced active mixer and transformer-based baluns for 77Â GHz radar applications

This paper presents a 130-nm BiCMOS active mixer dedicated to 77 GHz automotive radar applications. The architecture is based on a double-balanced Gilbert cell with integrated transformer-based baluns. Interconnections between devices, capacitor accesses and Tee-junctions are modeled using EM software in order to improve the simulation accuracy. Focusing on wideband operation, the transformer-based baluns are considered as part of the input matching network. Sizing of the transformer is detailed along with its amplitude and phase balance performances. The design of the input matching circuit integrating the transformer is presented, providing a 12-GHz bandwidth. Measured noise figure, conversion gain and compression point of the mixer are displayed and compared to the state of the art.