- 學位論文
低功率可攜式之離子感測酸鹼度計系統晶片設計
A Low-Power System Chip Design for Portable ISFET pH-Meter
摘要
Bergveld於1970年發明離子敏感型場效電晶體，其為一結合化學感測膜與金屬氧化物場效電晶體之固態元件，可以來選擇性感測電解液中離子的濃度。過去三十年以來，各種形形色色的製造方法、讀出電路及校正方式相繼被提出，但離子敏感型場效電晶體本身的不理想效應（包含光線、雜訊、溫度、時漂、遲滯、流速、基底效應、生命週期），限制了此感測元件之量測系統的精確度。 單一晶片設計為積體電路設計之趨勢，但此概念並不一定適用於所有系統中，本論文提出兩顆晶片設計，第一顆晶片為改良式浮動閘極讀出電路及帶隙能差參考電路，與離子敏感型場效電晶體封裝在印刷電路板上，製成一可拋棄式之感測棒；第二顆晶片為整合十六位元類比數位轉換器、十六位元數位校正電路及顯示驅動電路，用於將感測訊號資訊轉換至顯示器上，來實現可攜式筆型酸鹼度計之系統。 本篇論文所提出的筆型酸鹼度計系統，使用單顆CR-2032之3V標準電壓做為整個系統晶片設計，並使用TSMC 0.35um Mixed Signal 2P4M Polycide 3.3V製程技術完成設計與佈局。本論文所提出來的電路架構可以有效降低離子敏感型場效電晶體之不理想效應來減少誤差。整個系統連續使用時數超過1000小時以上，兩顆晶片平均消耗功率約為2.85uW，酸鹼值量測範圍從pH 2 ~ pH12，量測精確度達±0.001 pH。校正電路功能包含有單點、兩點及三點校正。
並列摘要
Bergveld invented ISFET in 1970. A solid device of ISFET which combines chemical membrane and metal-oxide-semicondictor sences selected ion-chroma in solution. Various manufactures, readout circuits and calibrations were presented in backward-looking thirty years, but ISFET’s undesirable effect which is including light, noise, temperature, drift, hysteresis, flow rate, body effect and life cycle is limited justness in measure machine. All in one chip is the currect trend in VLSI circuit design. But this concept isn’t suitable for all systems. This thesis presented the dual chip design. One combines improving floating-gate readout circuit and Bandgap reference circuit which is maked in a replaceable stick, and the other combines 16-bit SAR-ADC, 16-bit digital calibration circuit and display driver which is converted ISFET information to display panel and accomplish the portable pH-meter system. This thesis presents the portable pH-meter system which is designed by signal 3V CR-2032 battery and using TSMC 0.35um Mixed Signal 2P4M Polycide 3.3 technical manufacture to accomplish all designs and layouts. The new circuit architecture by the thesis presented can be reduced ISFET’s undesirable effect and drop error. The entire system’s battery life is over 1000 hours by continuing using, and two chip’s power consumption is approximative 2.85uW. This portable pH-meter system is accureted 0.001 pH, and can be measured pH value from 2 to 12. The functions of calibration circuit are incluing signal point, dual points and three points by calibration.