Auto-Tuned Transition Scheme in Bias-Flip Rectifier for Piezoelectric Energy Harvesting

The self-sustainable, ultra-low powered devices and sensor nodes are becoming quite popular just because of the availability of the micro-power generators. One of such micro-power generator is a piezoelectric energy harvester which converts the ambient mechanical vibration energy into the electrical energy. The piezoelectric energy harvester is capable of extracting 100’s of µW of power available. The most widely used interfacing circuit for the piezoelectric energy harvester is a bias-flip rectifier. In the conventional bias-flip rectifier, there is an inherent trade-off between the power extraction and the size of the external inductor. Based on the system demand, the designers often face challenges to generate a precise transition time for a particular value of the inductor. In this paper, an auto-tuned transition scheme for the bias-flip rectifier is presented. It is capable of generating and adjusting the transition time suitably based on the value of the inductor chosen. The proposed auto-tuned transition scheme is designed in 180 nm CMOS technology with a quiescent power consumption of 14.6 µW.