- 學位論文
應用於電子舌系統之電位式感測電路設計
Potentiometric Sensor Circuit Design for Electronic Tongue System
摘要
離子感測場效電晶體(Ion-Sensitive Field Effect Transistor, ISFET)發明至今已將近四十年，為使離子感測場效電晶體能有更高之量測準確度，根據目前研究顯示，必須克服之非理想效應分別有溫漂、時漂以及遲滯，其克服及補償之技術為一目前熱門議題。 本論文主要目的為克服溫度造成離子感測場效電晶體之非理想效應，並透過探討溫度感測器之設計與應用完成一兼具溫度感測及溫度補償效果之離子訊號讀出電路晶片。文中所設計之電路區塊包含一改良式臨界電壓萃取器之溫度感測電路、臨界電壓萃取式空乏型金屬氧化物半導體場效電晶體(Depletion-type Metal-Oxide- Semiconductor Field Effect Transistor, MOSFET)之溫度感測電路、臨界電壓萃取式訊號讀出電路、具有溫度補償效果之萃取式讀出電路以及高穩態低溫度係數之1.65V穩壓電路，並藉由實體晶片量測探討最佳之溫度補償電路架構設置。 本文所提出之具溫度補償讀出電路總消耗功率為889.3μW、靈敏度達54mV/pH、溫度補償前後溫度相關係數分別為4.01mV/℃與0.02mV/℃；而1.65V穩壓電路總消耗功率為91.642μW、溫度相關係數為4.847ppm/℃。
並列摘要
Ion-Sensitive Field Effect Transistor (ISFET) has been developed for almost forty years. In order to improve the performance of ISFET, as the research has showed, the effect of temperature, time drift and hysteresis should be overcome. Therefore, developing different compensation method on ISFETS is still a hot topic today that requires further research. The aim of this thesis is to overcome the effect of temperature on ISFET and to introduce a readout circuit with temperature-sensing and temperature compensation through the design and application of temperature sensor. The major circuits in this study include a modified VT extractor, a depletion-type MOSFET temperature sensing-circuit, an extractor-type readout circuit, a VT extractors based readout circuit of ISFET with temperature compensation, and a voltage regulator with a high stability and low temperature coefficient of frequency (TCF) of 1.65V. Further, through measuring the real chip, the best design of temperature-sensing circuit is proposed and discussed. The circuit proposed in this study dissipates a power as low as 889.3μW. The sensitivity reaches 54mV/pH, and the temperature coefficient before and after the temperature compensation is 4.01mV/℃ and 0.02mV/℃. In addition, a 1.65V voltage regulator’s total power consumption is 91.642μW, and the coefficient of temperature is 4.847ppm/℃.