過去三十年,離子敏感型場效電晶體為一熱門的研究課題。研究顯示離子敏感型場效電晶體具有許多缺陷,包括溫漂、時漂及遲滯等,這些因素限制了以此電晶體為感測元件之量測系統的準確度。另外,藉由感測器陣列可大幅提升感測訊號之可靠度與穩定性,多通道感測器及感測器陣列的生醫感測器系統亦是發展的趨勢。 本論文首先探討源極追隨訊號讀取電路因加入開關後,導致靈敏度降低的原因,並加以改善實現一以橋式源極浮接訊號讀取電路為基礎之二維(4X2)離子敏感型場效電晶體感測器陣列系統。因感測器陣列中每一感測器之輸出直流準位與受溫度影響之係數皆不同,故本研究提出解決的方法進行溫度補償及輸出電壓準位的調整,使感測器陣列中每一感測器的輸出訊號較不隨溫度漂移並將輸出電壓準位調整到接近或相同的程度,以利後端訊號處理。研究結果達成提升源極追隨電路靈敏度13%;完成二維橋式感測器陣列系統下線,感測器陣列溫度補償36%,同時降低輸出電壓準位差97.3%。 另外,考量時漂效應之模擬與補償,嘗試於離子敏感型場效電晶體之巨集模型中加入時漂效應及時漂對溫度與酸鹼值的變化關係。藉由TSMC 0.35UM 2P4M製程下線量測,與使用HSPICE巨集模型模擬之比較結果,獲得時漂模擬與量測均方根誤差為2.2%,時漂對溫度的模擬與量測均方根誤差為6.6%,時漂對酸鹼值的模擬與量測均方根誤差為2.4%。結果顯示,此一巨集模型將可加速時漂補償電路的設計。
Ion Sensitive Field-Effect Transistor had been a hot research topic in the past 30 years. Research indicting ISFET have some drawbacks such as temperature effect, drift and hysteresis. These factors limit the accuracy of ISFET signal extraction. Moreover, the accuracy of the signal readout is greatly improved based on a large number of sensors. ISFET-based sensor array on biological application is also a trend. This thesis first explored the cause of pH sensitivity loss of the source follower configuration readout circuit. The improvement present a 4 by 2 ISFET sensor array system based on a bridge-type floating source readout interface. Due to the different DC level and temperature coefficient of each sensor in the array, the compensation methods have been proposed. Experimental results present the improvement of pH sensitivity in source follower readout circuit, temperature compensation and output DC level to 13%, 36% and 97.3%, respectively. Furthermore, an ISFET behavioral macromodel take into account non-ideal drift effects have been developed. These models were then used to design bridge-type floating source interface circuit. The modeled-versus-measured fit of the dependence of drift rate on long time period, temperature and different pH value present a RMS error of 2.2%, 2.4% and 6.6%, respectively. The developed macromodel can be adapted to speed up the design of silicon-based chemical-microsystem.