壓電發電元件自供電同步切換介面電路研究

Abstract

近年來M2M (Machine to Machine)與互聯網(Internet of Things, IOT)概念越來越受到業界關注，為了收集各種環境的狀態，其感測器需求量將會大增，然而隨著半導體技術的進步，越來越多感測器只需要損耗幾十微瓦的功率。為了解決感測器供電問題，目前通過壓電能量擷取技術，能將環境中的振動能轉換成電能，可以提供幾十至幾百微瓦的功率，其中利用同步切換介面電路，能有效提升壓電能量擷取系統的功率。 本論文提出一種利用壓電元件所產生的電能，來提供同步切換介面電路操作，達到自供電設計。電路架構由峰值檢知器、比較器與數位開關組成，利用峰值檢知器與比較器產生開關控制訊號。以微機電製程製作的微壓電發電元件輸出功率通常小於100 μW，較複雜電路設計可能無法利用壓電元件來驅動，然而自供電開關切換技術架構因設計簡單，較適用以微機電製程製作的微壓電發電元件。 本論文提出自供電同步切換介面電路使用台積0.25 μm高壓製程。其整體消耗功率為26 μW，操作頻率為120 Hz，最佳附載阻抗為1.5 MΩ，在最佳附載阻抗下輸出功率為43.42 μW，相較於標準能量擷取電路提高了3.36倍。

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.