Characterization of Systematic and Random Diode Mismatches in Antiparallel-Diode Mixers

Diode mismatch in an antiparallel-diode (APD) mixer results in an unwanted virtual local-oscillator (LO) leakage. At a radio system level, the virtual LO leakage is primarily a challenge of meeting spurious emission requirements. At a device level, it is a challenge of circuit yield, determined by the statistical variation in diode mismatch of a semiconductor fabrication process. This paper introduces methods of characterizing diode mismatch in APD mixers. The parameters of these characterization methods can be used to make an informed selection of the fabrication process, diode size, and LO pump power for reduced virtual LO leakage and improved yield.