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 mu W 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 mu W.