應用於無線近身網路之嵌入式晶體振盪器

Abstract

在本篇論文裡，我們介紹一個應用於無線近身網路的嵌入式晶體振盪器和基頻低功率設計流程，來降低整個系統的功率消耗和面積使用。

近年來，健康照護的系統應用於無線近身網路愈來愈受到人們的重視，尤其是針對人體生醫訊號的偵測。在這樣的應用中，可以從配戴在身上的無線感測器對人體訊號做長時間的偵測，並以無線的方式將資料傳送給整合在手機或個人數位助理的接收端。基於這樣的一個應用，極低的功率消耗跟高度整合的面積會是系統不可或缺的需求。我們使用了低功率的設計流程來降低整個基頻的功率消耗，儘管整個基頻的功率消耗已經非常低。但從整個系統來看，我們可以發現功率消耗主要由晶片外部的一些元件佔非常大的部份，像是石英晶體與其搭配使用的振盪器。不僅如此，這些晶片外部的元件同樣佔據了相當大的面積使用，對整個系統造成額外的負擔，於是嵌入式晶體振盪器[1]被提出來取代這些晶片外部所使用元件。嵌入式晶體振盪器是藉由互補金氧半導體製程的方式，將晶體振盪器整合進單一晶片中，如此一來可以大大地降低系統的製造成本、面積及功率消耗。在本篇論文我們對整個嵌入式晶體振盪器的行為做一個詳盡的闡述，並分析頻率校準的設計，最後建立了一個嵌入式晶體振盪器的原型來驗證這樣的行為。藉由使用嵌入式晶體振盪器以及基頻的低功率設計流程，整個系統將可以降低73％的功率消耗和53％的面積使用。

In this thesis we propose an Embedded Crystal (eCrystal) oscillator and baseband low power design flow for Wireless Body Area Network (WBAN) applications to assure the overall system power and area reduction.

In the recent years, people have attached great importance to healthcare monitoring system for WBAN applications. There are multiple wireless sensor nodes (WSNs) placed on the human body for long-time monitoring. The WSNs transmit data wirelessly to a central processing node (CPN) integrated into mobile phones or personal digital assistants (PDAs). Ultra-low power and tiny integrated area are the features required in such applications. A low power design flow comprising Multiple Supply Voltage (MSV) and power gating is used to reduce baseband power consumption. However, the overall system power is dominated by some off-chip components, e.g. quartz crystal and oscillator. Besides, these external components also occupy very large system area. Therefore, an eCrystal oscillator [1] has been proposed to replace these external components, and this can largely reduce manufacturing cost, system area, and power consumption. We elaborate and analyze the frequency error calibration of eCrystal oscillator and establish the prototype platform to verify the system behavior with eCrystal oscillator. By the use of eCrystal oscillator and baseband low power design flow, the system will have 73% power reduction and 53% area reduction.