A Fully-Integrated Kinetic Energy Harvesting Circuit with a Transposed Hybrid Series-Parallel SC DC-DC

A fully integrated piezoelectric kinetic energy harvesting circuit is presented, in which the active rectifier adopts 5-T amplifiers instead of high-gain comparators to reduce the power loss at very low tapping frequencies. For the on-chip switched-capacitor DC-DC, a transposed hybrid series-parallel structure is proposed to reduce the number of capacitors and switches remarkably, resulting in small chip area and high efficiency. Fabricated in a 0.18-μm CMOS process with a die size of 0.748 mm
²
, the peak output power is 121.8 μW at about 2 Hz frequency manual tapping on the piezoelectric transducer.