電子鼻系統已經廣泛應用於如: 環境中PM的危害偵測、食品新鮮度、以及一些特殊疾病的預測等等。相較於傳統使用大型儀器進行氣味成分分析的方式，電子鼻擁有微型化、低功耗、低製作成本，且能快速得到量化結果等許多優點。電子鼻系統由氣體感測器陣列、信號讀取介面電路和資料擷取及辨識系統組成。本研究中針對電阻式氣體感測器作為感測器種類，其感測機制為電阻變化。此種感測器可整合在晶片製程，且信號讀取電路簡單，符合微型化、低成本、低功耗等目標。信號讀取電路採用週期變化的介面電路，此種介面電路的數位輸出訊號可直接送至微控制器或訊號擷取卡做後續讀值及辨識，在複雜度、傳輸時間上具有優勢，因此成為本研究的目標架構。在回顧相關文獻後，可發現電流鏡的架構在其他文獻中被大量使用於複製與增益流入感測器的電流，使電路必須承受電流鏡的非理想現象，如:不匹配、通道長度調變效應的影響，且電流鏡增加功率消耗、使用大面積佈局等等缺點也都是不符合介面電路發展趨勢的。本研究提出由TSMC 90nm CMOS 1P9M製程所製作之低功耗、低複雜度的電阻式感測器介面電路，在轉換過程免除電流鏡的使用，並利用對數壓縮的方式來達到廣範圍適應電阻，最後得到週期隨阻值變化的突波訊號。本論文呈現設計原理與模擬，並驗證阻值轉換的功能性，最後進行量測與比較。

The electronic nose (E-Nose) system has been widely applied to many aspects, such as the monitoring of hazardous particulate matter in the environment, the quality control of foods, and the diagnosis of specific disease. Compared to traditional gas analysis methods with the use of huge instrument, the electronic nose has potential for minimized size, low operating power, low cost, and the capability of rapid quantization of olfaction. An electronic nose system primarily consists of gas sensor array, signal transducer readout circuit as well as a data gathering and pattern recognition system. In this thesis, resistive gas sensor is the target sensor. This type of sensor, which is capable to be fabricated through the CMOS standard process, has the advantages on relative simplicity of its readout circuit. It fits the purpose of minimized size, low cost and low power. The pulse latency based interface circuit is adopted. The digital signal, which is the type of output signal of this interface, can be directly connected to the microcontroller unit or the data acquisition card for further data gathering and recognition. Since the pulse latency, or time domain based interfaces surpass other type of interface in complexity and transfer time, it becomes the main architecture of interface circuitry in this research. In the reviewing of the literature, it can be observed that the architecture of current mirror is widely adopted for coupling or signal processing in current-mode circuit design. Hence, the interface circuit inherently suffers from the non-ideal effect of current mirror, such as mismatch and channel-length modulation. In addition, the current mirror increases the power consumption and often requires large area in layout. These disadvantages are incompatible with the development trend of interface circuits. This research will introduce a low power, low complexity interface circuit for resistive sensor which is fabricated by TSMC 90nm CMOS 1P9M process. In addition to the elimination of current mirror during the transforming of resistance value of sensor, this interface circuit also takes the advantage of logarithmic compression for wide input adaptive resistance range. Finally, there are spike signals generated at output and the time intervals vary with the resistance values of sensors. This thesis presents the principle of the proposed interface circuit and simulations with HSPICE tool. The functionality of transforming the resistance value is validated. Lastly, the measurement result of the interface circuit will also be presented and compared with other literature.

摘 要
ABSTRACT
目 錄
圖 目 錄
表 目 錄
第一章 緒論-----1
1.1 研究背景-----1
1.2 研究動機與目的-----4
1.3 章節簡介-----4
第二章 文獻回顧-----5
2.1 電子鼻簡介-----5
2.2 氣體感測器種類-----7
2.3 電阻式氣體感測器介面電路-----17
2.3.1 類比數位轉換器為主-----17
2.3.2 脈衝寬度調變為主-----20
第三章 設計與模擬-----25
3.1整體系統架構介紹-----26
3.2 電阻到對數轉換器-----26
3.2.1 對數轉換器可適用電阻範圍分析-----34
3.3 比較器與輸入偏移電壓消除電路-----40
3.3.1 介面電路可適用電阻範圍分析-----45
3.4 介面電路佈局與考量-----53
第四章 介面電路量測結果-----54
4.1 量測設置-----54
4.2 量測結果-----54
4.3 結論與文獻比較-----63
第五章 結論與未來展望-----66
參考文獻-----67

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