A dual source microscale energy harvesting system for wireless sensor networks

This paper presents a muli-input multi-output battery-less energy harvesting system for microscale wireless sensor nodes that combines piezoelectric and photovoltaic energy sources. The system undergoes four states of operation to achieve two voltage levels at the output of 1.2V and 3V. It is a dual path system that uses a single inductor for both boost and buck converter. A maximum power point tracking technique is introduced to lock to the maximum power voltage of the photovoltaic transducer. The system was implemented in UMC CMOS 130nm technology. It achieves an efficiency up to 74% at 10mW of harvested power.