使用溫度補償技術的高精確度阻抗數位轉換器之設計

Abstract

本篇論文針對阻抗量測電路提出了新的技巧，改善傳統方法所遇到的問題。阻抗量測器在日常生活中很常見，例如體脂機，而在生物醫療方面也能夠用來進行癌細胞檢測，除了上述中較常見的應用之外，只要是物質的阻抗有變化時都能夠使用阻抗量測器進行檢測，例如酒類的釀造或是肉品的腐敗之類的。為了能在各種應用中能更準確的觀察阻抗的細微變化，阻抗量測器的精確度需要被考量，而因為在各個應用中的環境溫度並不相同，所以阻抗量測器受環境溫度所影響的問題也是需要被注意。本論文提出使用相位誤差抵銷技巧，改善了傳統架構中在阻抗的相位量測上精確度較差的問題。並且在系統中加入了溫度補償技巧以及積分類比數位轉換器，避免阻抗量測器受到環境溫度所影響而且輸出為數位信號可以讓後端電腦能夠直接分析資料。本論文的阻抗數位轉換器以0.18-μm互補式金屬氧化物半導體製程製作並驗證。此阻抗數位轉換器使用1.8V的供應電壓源，消耗的功率為7.92mW，在輸出結果為類比信號時，阻抗振幅量測誤差為+1.03%/-0.93%，阻抗相位的量測誤差為+0.87°/-0.73°，在輸出結果為數位信號時，阻抗振幅量測誤差為+1.35%/-1.23%，阻抗相位的量測誤差為+1.06°/-0.89°，在溫度範圍25°C至100°C時，阻抗振幅端的溫度係數為180 ppm/°C，阻抗相位端的溫度係數為156 ppm/°C。

An improved mechanism for impedance measurement analyzer is presented in this thesis to solve the problem in the traditional measurement technique. Impedance measurement analyzer is commonly used in daily life, such as the body fat monitor. In biomedical applications, it can be used to detect cancer cells. In addition to the common applications mentioned above, as long as the impedance of the substance changes, it can be detected by the impedance measurement analyzer, such as wine brewing or the corruption of foods…etc. To more accurately observe small changes in impedance, the accuracy of the impedance measurement analyzer needs to be considered. Another point that needs to be improved is that the impedance measurement analyzer is affected by temperature. Because the temperature in each application is not the same, the measurement results may have errors. The phase error cancellation technique is presented in this thesis to improve the problem of the phase error in phase measurement. Besides, the temperature compensation technique is used in the system to reduce the influence of temperature. In the end, the integrating analog-to-digital converter is integrated into the system to implement an impedance-to-digital converter. The impedance-to-digital converter is fabricated in the 0.18-μm CMOS process. The power of chip is 7.92mW. In the analog output mode, the error of magnitude measurement is +1.03%/-0.93%. The error of phase measurement is +0.87°/-0.73°. In the digital output mode, the error of magnitude measurement is +1.35%/-1.23%. The error of phase measurement is +1.06°/-0.89°. In the temperature range from 25°C to 100°C, the temperature coefficient of magnitude measurement is 180 ppm/°C. The phase coefficient of phase measurement is 156 ppm/°C.