Performance Analysis of Multistage Voltage Doubler Rectifier for RF Energy Harvesting

The conversion of electromagnetic energy into DC electrical energy is increasingly considered as the most appropriate solution to overcome the energy dependence of wireless sensor nodes (WSN). However, due to RF exposure limits, the output voltage levels reached are generally low. To amplify this voltage, the use of multi-stage voltage doubler (MSVD) rectifiers is the solution proposed by most designers. Nevertheless, it is recalled that in addition to the supply voltage, the effective of a WSN also depends on the harvested power by the conversion circuit; this issue is not very often dealt with in the design of the MSVDs. In this paper, it is proposed an analysis of the MSVDs to define how beneficial it to amplify the DC voltage without degrading the output power level of the conversion circuit. To consider these two performance criteria, a Rectifier Figure of Merit (RFoM) is defined. The results obtained through simulations with the Advanced Design System (ADS) software demonstrate the existence of an optimum number of stages that is linked to the RF power level incident. As a result of this observation, a relationship between the incident RF power and the optimal number of stages of the MSVD is established in this paper.