石英震盪器可以提供相當穩定的參考訊號，所以在通訊系統中扮演重要的角色。隨著物聯網需求的增加，無線感測網路往往使用電池供電，為了更長的使用時間，低功耗變得非常受重視。循環工作方法常用於無線通訊網路，使電路在大部分的時間處於待機睡眠狀態，在需要的時候才觸發起動。由於石英振盪器的啟動時間遠大於收發機中的其他電路，會拖累整體的啟動時間以及啟動所需耗能。在本篇論文中，我們採用兩階段注入技巧配合頻率與相位校正方法來加速石英震盪器的時間起振。經由本方法，配合10 MHz的石英晶體，起振時間由9.21毫秒縮減為55微秒，起振所需耗能僅57豪微焦耳。本電路實現於台積電180奈米互補式金屬氧化物半導體製程，配合1.2伏特的電源電壓。

Crystal oscillators (XO) play an important role in communication systems as a reliable reference signal. In recent years, the demand of Internet-of-Thing (IoT) is increasing rapidly. Since the wireless sensor node is usually powered by batteries, ultra-low-power consumption has become an important specification of IoT devices. The duty-cycled operation is a superior solution for ultra-low-power wireless radio, most of the components in the radio remain sleeping during the standby mode and are only activated when needed. When it comes to the start-up process of duty-cycling transceivers, crystal oscillators take up the vast majority of the start-up time since they take relatively long time (~ms) to start-up. In this thesis, we adopts 2-step injection technique with a frequency and phase alignment calibration method to improve the start-up time of the crystal oscillator. For a 10 MHz crystal, the proposed technique reduces the start-up time from 9.21 ms to 55 s and consume only 57 nJ of start-up energy. The prototype of the proposed method is designed in TSMC 180-nm CMOS technology with 1.2 V supply voltage.

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