57-GHz Low-Power Subharmonic Parametric Downconverter Exploiting Capacitance Nonlinearity in SiGe BiCMOS

This work presents the full analysis and implementation of a proof-of-concept monolithic millimeter-wave integrated circuit (MMIC) that behaves as a subharmonic parametric downconverter mixer. Contrarily to other integrated parametric downconverters, the circuit exploits the optimized, high nonlinear C-V characteristics of a diode-connected SiGe heterojunction bipolar transistor (HBT) to achieve the subharmonic performance. The fabricated prototype demonstrates conversion gain (CG) up to 14 dB while consuming only 235 µW. Additionally, it is shown that due to the negative conductance induced by the time-variant capacitance amplification of the input signal also occurs reaching a similar gain. To the best knowledge of the authors, this is the first integrated subharmonic parametric mixer ever reported in the V-band while providing positive conversion gain.