Common-mode interference and power conversion efficiency of differential rectifiers in RF energy harvesters

This paper studies the effect of amplitude and phase mismatch on the power conversion efficiency of differentially-drive rectifiers employing cross-coupled MOSFETs. The analysis begins by defining the different operational regions of the differential rectifier and how the common-mode interference resulting from amplitude and phase mismatches affects the symmetrical operation of the rectifier. A mathematical model is developed to estimate the output voltage and the power conversion efficiency under such mismatching conditions. Simulation and measurement results are provided to validate the mathematical model through the design of a three-stage differential rectifier in 0.13 μ m CMOS technology. Modification to the original rectifier design using a tail load topology is also proposed to reduce the effect of mismatches.