An AC/DC voltage doubler with configurable power supply schemes for vibrational energy harvesting

This paper presents an ac/dc voltage doubler, where the output dc voltage is twice the input ac voltage amplitude. Two configurable power supply schemes are explored for the voltage doubler in vibrational energy harvesting applications. An `input-powered' power supply scheme eliminates standby power consumption of the circuit when the harvester is not active. Alternatively, a `cross-connected' power supply scheme reduces the minimum input voltage without additional circuit cost. Implemented in On Semi 3M-2P 0.5 μm CMOS technology, the circuit is first benchtop characterized with a signal generator and then also demonstrated with a vibrational energy harvester. A maximum power efficiency of 87% is achieved using the input-powered scheme for a 1.5 V ac input amplitude and 960 μW of output power. In the cross-connected scheme, the circuit is able to rectify input voltage amplitudes as low as 400 mV, below the transistor threshold voltage of 700 mV.