Improved circuit design on self-powered synchronized switching techniques for piezoelectric energy harvesting

In recent years, the concept of the machine to machine (M2M) and the internet of things (IoT) have drawn the industry’s much attention. In order to monitor different status of the environment, the requirement for sensors are increasing. Due to the advancement of semiconductor fabrication technologies, the power consumption of the sensor was reduced to about ten microwatts. In order to solve the power supply of the sensor, the energy harvesting technology can transform the vibrational energy into electrical energy from the environment. The energy harvesting technology can provide power in scales of tens to hundreds microwatts. Using synchronized switching technology, one can increase the output power of the energy harvesting technology. This thesis presents a self-powered synchronized switching technique for piezoelectric energy harvesting. The architecture consists of a peak detector, a comparator, and a digital switch. The control signal for the digital switch is generated by the peak detector and the comparator. With the MEMS process, the output power of the piezoelectric element is less than 100 microwatts. Therefore, the complicated design of the interface circuit is inadequate to be driven by the piezoelectric element. Nevertheless, the design of the self-powered synchronized switching techniques is much simple and thus more appropriate the piezoelectric element fabricated by the MEMS process. This proposed a self-powered synchronized switching interface circuit is fabricated by TSMC 0.25 μm 60V high voltage 1P3M cmos process. The power consumption is 26 μW at the element resonant frequency of 120 Hz. The optimal output power is 43.42 μW under the optimal load of 1.5 MΩ. The self-powered synchronized switching interface circuit can increase the power extraction to 3.36 times comparing to the standard circuit.