隨著健康觀念越來越普及，對於能隨時隨地地進行身體檢測的長期健康監測的重要性隨之增加。針對這種需求，可穿戴式電路應用在人體局域網被認為是一種可行性的作法。然而，對於此種長期穿戴式監測的系統而言，能量的補充仍是一個關鍵的議題。因此，本論文研究使用壓電材料汲取能量，壓電裝置可以安裝在鞋子擠壓或是安裝在身上擺動來採集能量。本論文設計測試電路量測輸出電壓反應於機械式地推動的上升程度，並與模擬模組做相互比較，模擬數據與實際電路的比較結果十分一致。本論文也對壓電裝置的功率進行測量，它取決於壓電材料壓縮的強度及時間，以本論文研究來說，此能量採集器的功率在1.46uW範圍內，因為此能量非常小，本論文也研究一個潛在的可行性電路，這個候選的電路為浮動閘極記憶體，它可適用於存取類比值，這類比數值反應了施力訊號能量兩。此記憶體利用台積電0.35um製程技術實現於晶片上，其面積為136.375um*131.525 µm。量測結果呈現了寫入電流的反應，其量測結果在覆寫單元需要至少10分鐘的時間運作 ，並根據兩個模式的電壓曲線設定出能以邏輯形式讀取記憶體狀態的讀取模式。本論文結合壓電裝置與快閃記憶體，利用壓電裝置產生的能量驅動快閃記憶體，其結果能在100分鐘完成寫入。

With increasing levels of health awareness among people, the importance of long-term medical monitoring has increased along with the need for body detection at any given time and place. To serve these needs, wearable circuits, often in form of a body area network (BAN), are possible solutions. However, for long-term wearable monitoring the energy supply remains a critical issue. An energy harvesting circuit is studied in this thesis which extracts energy from a piezoelectric device. The device may eventually be energized by compression such as when worn under a shoe or by gravity oscillation when worn on the body. In this study a test circuit is built to measure the voltage rise on a storage capacitor in response to mechanically nudging the piezo device. The circuit is bench tested and compared with analytical results obtained for a model of this system showing close agreement. The harvested power is also measured. It depends on the actual strength and duration pattern of the piezoelectric compression. For the actual setup studied here, the harvested power is in the range of 1.46uW. Since this power is small, this study further investigates a potentially useful circuit that can be energized by the harvester. A candidate circuit is the MOS floating gate memory cell which is suitable to store an analog value corresponding to applied signal energy. A memory cell is realized in TSMC 0.35um integrated process technology with an active are of 136.375 µm*131.525 µm. Measured results are presented and show the response to a programming current. Erasure of the rewritable cell needs about 10 minutes using CMOS compatible voltage levels. According to the programmed voltage, an on-chip comparator can read the memory state and provide a binary logic output. Measurement shows that programming the cell with the energy of the piezoelectric device of this study enables battery-less piezo strain recording over a time period of about 100 minutes.

致謝 i
摘要 ii
Abstract iii
Context v
List of Figures viii
List of Tables xii
Chapter 1 Introduction 1
1.1 Background 1
1-2 Contribution 2
1-3 Thesis organization 2
Chapter 2 Energy Harvester and Memory Design 4
2.1 System diagram 4
2.2 Piezoelectric device 5
2.2.1 Equivalent model 7
2.2.2 Excitation waveform 8
2.3 Rectifier 9
2.3.2 Active harvester circuit 10
2.3.3 Diode 11
2.4 Energy storage 12
2.5 Harvester model 13
2.6 Floating gate memory 15
2.6.1 Operating modes 18
2.6.2 Tunnel Capacitor 19
2.7 Floating gate memory circuit implementation 20
Chapter 3 Measurement Results 22
3.1 Piezoelectric transducer capacitance 22
3.2 Mechanical stimulator for nudging the piezo transducer 25
3.3 Measurement of the open circuit voltage 29
3.4 Harvester voltage transfer measurement 31
3.5 Power transfer measurement 32
3.6 Floating-gate memory measurement 39
3.6.1 Buffer measurement 40
3.6.2 Floating-gate transistor 41
3.6.3 Current source 42
3.6.4 Testing printed circuit board 43
3.7 Measurement of floating-gate transistor functions in different states 45
3.8 Measurement of time for erasing and programming 47
3.9 Measurement of memory function using connected piezo device 49
3.10 Measured results summary 50
Chapter 4 Conclusions and Future Work 52
4.1 Conclusions 52
4.2 Future work 53
References 54

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