A battery-less power management circuit for RF energy harvesting with input voltage regulation and synchronous rectification

This paper presents a battery-less power management circuit for RF energy harvesting applications. In general rectenna (antenna and rectifier) exhibits the maximum efficiency for a particular range of load resistance at different values of RF power received by the antenna. To track maximum power transfer and reduce the power overhead of the various modules an efficient and simple scheme is presented in this paper to maintain effective input resistance of the boost converter equal to the effective output resistance of the rectenna. Maximum power point tracking (MPPT) is achieved at the input of boost converter and synchronous rectification technique is also used to stop the loss of energy from output capacitor of the boost converter. It is shown that MPPT as a function of effective output resistance of the rectenna can be maintained for a range of input power without changing the emulated resistance at the input of the boost converter. The entire circuit is designed, optimized and simulated in 180nm mixed-mode CMOS technology. Post layout simulation results are presented for -10dBm input power at 950MHz received by the antenna. Output voltage of 1V is generated across a load resistance of 76 kΩ with achieved boost converter efficiency of 80%.