A Non-Iterative Method for Design of Radio Frequency Energy Harvesters

This paper proposes a non-iterative method for the design of Radio Frequency Energy Harvesters (RFEHs) with maximum power conversion efficiency (PCE) at any given input power level. Because of the non-linear interdependency of the rectifier’s input impedance and its input voltage to matching network’s and rectifier’s parameters, the design of an RFEH with maximum efficiency requires numerous lengthy transient simulations of the entire energy harvester. Splitting the design space into two separate spaces which only interact with each other through the input voltage of the rectifier, the design goal can now be redefined to finding an optimum input voltage amplitude that maximizes the efficiency of the rectifier while enabling maximum power transfer from antenna to the input of the rectifier at the same time. Using the proposed method, the number of the required simulations to find optimum design values is significantly reduced compared to all previous methods reported in the literature, which also has been experimentally verified by designing three battery-loaded RFEHs at different input power levels in TSMC’s 130nm CMOS process. To further accelerate the design process, closed-form equations to calculate the efficiency and the input resistance of the rectifier are derived for the battery-loaded Dickson charge pump rectifiers.