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Title: | 應用於可攜式氣體感測系統之CMOS混和訊號晶片設計與實現 Design and Implementation of CMOS Mixed-signal SoC for Portable Gas Detection System |
Authors: | Te-Hsuen Tzeng 曾德軒 |
Advisor: | 呂學士 |
Keyword: | 氣相層析系統,校正電路,氣體感測器,電阻讀取電路,三角積分器, Gas chromatography,Calibration circuit,Delta sigma modulator,Gas detection,Resistor type readout circuit, |
Publication Year : | 2017 |
Degree: | 博士 |
Abstract: | 近年來由於環境安全的議題廣泛地受到社會大眾的重視,投入氣體檢測系統研發的量能大幅成長,同時,因應健康照護的需求,呼吸氣體檢測技術也逐漸受到重視。在另一方面,如系統應用的實踐上,為了實現Point-of-Care Testing (POCT)的願景,現有的氣體感測系統即需要進一步的改進。有鑒於此,本論文設計了一組針對肺癌相關揮發性有機氣體檢測的可攜式微氣相層析系統,該系統尺寸為16cm*11cm*11cm,整合了MEMS前濃縮管、MEMS分離管柱、CMOS氣體感測器和讀取電路,後端並搭配完整的訊號處理與分析。其中,晶片介面電路的部分使用台積電 0.35 μm 製程技術來實現。為了克服感測器製程變異造成的初始電阻值偏差,設計了一組1M~10MΩ的校正轉換電路,之後再透過具備Chopper架構的低雜訊放大器以及10-bit SAR ADC將訊號轉換成數位。該系統可以偵測七種肺癌相關的揮發性有機氣體(acetone, 2-butanone, benzene, heptane, toluene, m-xylene, 1,3,5-trimethylbenzene),且具備良好的濃度線性度R2 = 0.985。其中針對1,3,5-trimethylbenzene的揮發氣體濃度感測極限可達15ppb。
此外,因應氣體檢測的需求,本論文也提出了新穎的電阻-數位轉換電路,該電路由聯華電子的0.18um CMOS製程技術實現。藉由整合電阻感測器與一階一位元的連續時間三角積分器電路,大幅簡化了讀取電路的複雜度。該電路系統是用的電阻範圍為2.5MΩ 到 1GΩ,其不準確度只有 0.03%。在1.024MHz的系統時脈以及500Hz的頻寬操作下其SNDR可達82.57dB。此外為了克服氣體系統因為升降溫過程帶來的訊號干擾,搭配了一組在溫度範圍25˚C~75˚C變化3.9ppm/˚C的指數曲線補償能帶參考電路。 本研究完成高精準度的電路與微小化的系統將可為次世代氣體檢測系統提出一完整的系統架構,有助於相關應用的實現。 Due to the highly valued issues on environmental safety by the public, research of gas-sensing systems have become increasingly prevalent in recent years. In addition to monitoring environmental air quality, there is emerging aid of using gas-sensing systems for medical diagnose. In order to realize Point-of-Care Testing (POCT), it is necessary to develop a gas detection system with smaller size and more user friendly. In this dissertation, a portable micro gas chromatography (µGC) system for lung cancer associated volatile organic compounds (VOCs) detection is realized. This system is composed of an MEMS preconcentrator, an MEMS separation column, a CMOS gas detector, a readout circuit and a completely off-chip signal process with a dimension of 16cm*11cm*11cm. The chip is fabricated by a TSMC 0.35 µm 2P4M process including a 1M~10MΩ sensor calibration circuit, low-noise chopper instrumentation amplifier (IA), 10 bit analog to digital converter. Experimental results show that the system is able to detect seven types of lung cancer associated VOCs (acetone, 2-butanone, benzene, heptane, toluene, m-xylene, 1,3,5-trimethylbenzene). The concentration linearity is R2 = 0.985 and the detection sensitivity is up to 15 ppb with 1,3,5-trimethylbenzene. In addition, this dissertation also proposed a resistance-to-digital sensor readout integrator circuit for gas detection system fabricated in a 0.18um CMOS technology. By placing a resistive type sensor with a 1st-order 1-bit continuous-time delta sigma modulator (CTDSM), the proposed architecture simplifies the conventional resistive readout circuits and achieves a wide input range from 2.5MΩ to 1GΩ with an inaccuracy of 0.03%. It operates at 1.024MHz and achieves a peak SNDR of 82.57dB with a 500Hz bandwidth. An exponential curvature-compensated bandgap reference with 3.9ppm/˚C between temperature range 25˚C~75˚C is used to mitigate the errors caused by heating processes needed in the gas detection systems. The highly precise circuit and smaller system realized in this research will provide a more complete structure of gas detection system for the next generation, which can benefit the related application in the future. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/20361 |
DOI: | 10.6342/NTU201704215 |
Fulltext Rights: | 未授權 |
Appears in Collections: | 電子工程學研究所 |
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ntu-106-1.pdf Restricted Access | 8.12 MB | Adobe PDF |
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