應用於無線近身網路之可調式全數位時脈產生器

Abstract

對於逐漸受到重視的無線近身網路來說，高可靠度、可攜式與低製造成本的需求成為近年來最重要的研究主題之一。準確無誤地偵測人體生醫資訊，並且以有限的功率消耗加以傳輸訊號是無線近身網路的主要訴求。而在微小的感測貼片上做系統整合則是相當大的挑戰。 本篇論文將會針對應用於無線近身網路的時脈產生器做介紹，並以高可靠度、低功耗、低面積的觀點來設計一個可調式全數位時脈產生器。藉由可調整相位及頻率的時脈產生器與動態取樣相位頻率調整技術搭配，可在傳輸的封包錯誤率達到1%時，使整體效能僅有0.25dB損耗，同時並降低接收端的類比轉數位電路功耗達46%。而為了更進一步降低前述時脈產生器的功率消耗，本篇論文也提出一種應用遲滯電路來設計數位控制振盪器的方法，所設計的5MHz數位振盪器，其最小解析度可達0.78ps，功率消耗僅為2.6uW。在本篇論文的最後將會介紹一種可容忍製程、電壓、溫度飄移的全數位時脈產生器來當作可調式全數位時脈產生器的訊號源，其功率消耗為343uW、頻率誤差最大為0.002%，可搭配頻率控制電路來取代傳統的石英振盪器。而以上所述的可調式全數位時脈產生器共可在無線感測端降低89.8%與88.1%的功率與面積消耗，使其達成在無線近身網路上高可靠度、可攜式與低製造成本的需求。

For wireless body area network applications, the reliability, portability and cost are the significant studies in the recent years. In order to accurately monitor the biomedical signals without interference, system reliability is the challenge. For battery limited applications, the feature of low power consumption is undoubtedly required whenever the system is operating or standby. The demand of small size in sensor tags increases the difficulty in system integration, especially within a common used quartz crystal oscillator. In this thesis, we propose an all-digital tunable clock generator for wireless body area network applications. For 46 % ADC power reduction and only 0.25 dB SNR loss at PER=1 %, a phase-frequency tunable clock generator is applied with dynamic phase-frequency recovery technologies. So as to reduce power consumption on the always-on clock generator, a hysteresis-delay-cell-based digitally controlled oscillator is introduced, which has 0.78 ps delay resolution and consumes 2.6 uW at 5 MHz. Finally, an all-digital and cell-based PVT tolerance clock generator is described for replacing the reference quartz crystal oscillator. It achieves 343 uW and 0.002 % maximum frequency offset by frequency tuning capability. The overall designs enable the power and area reduction by 89.8 % and 88.1 % in wireless sensor nodes, respectively.