Enhanced bias-flip rectifier with ultra-low power control for piezo electric energy harvester in the microwatt application scenario

Low power devices promote the development of micro power generators (MPGs). There is an increasing interest in harvesting ambient vibration energy through piezoelectric means by which one can potentially draw 10-100´s of μW of available power. The limitations of existing piezoelectric harvesters is in their interface circuitry consuming large power and also large amount of charge getting wasted in charging and discharging large capacitance associated with the piezo device. In this paper, an enhanced bias-flip rectifier topology that can improve the power extraction capability from piezoelectric harvesters is presented. It has been shown that the proposed rectifier topology has 4X more output power over conventional full-bridge rectifiers and voltage doublers and 3.25 times maximum output power in comparison to existing bias-flip topology. The proposed interface circuitry consumes ultra low power (less than 6 μW) and achieves a near ideal inversion coefficient required for the perfect bias flipping.