本文主要是針對設計一個電容感測信號處理系統，它能夠把電容值轉換變成數位讀出值並且也具備高準確性及短轉換時間。這系統主要是由電流轉換器、類比開關、電流源、類比/數位轉換器和 32-bit ARM所組成，這系統使用的 32-bit ARM型號是S3C4510B。此系統的數位讀出值範圍從0000到FFFF對應到電容值的0pF到2pF。並具有數位輸出及對電容感測變化的增益作自動校正的功能，且補償電壓和寄生電容的影響也能被消除。因此，數位讀出值與電容感測變化的關係可表現出高線性。轉換時間和最大非線性分別低於100 和24ppm。
引用術語 – 電容感測器，即時測量電流轉換器，單晶處理器。

This paper presents the design of a capacitive sensor signal processing system, which is capable of converting the capacitance change into digital signal output with high accuracy and short conversion time. The system consists the current conveyors, analog switches, current source, A/D converter and 32-bit advanced RISC machine (ARM). The digital readout ranges from 0000 to FFFF corresponding to the capacitance change ranging from 0 pF to 2 pF. Due to the functions of proposed system, the gain of digital readout versus sensor-capacitance change can be calibrated automatically. The effects of offset voltage and parasitic capacitance can be eliminated. Therefore, the relation of digital readout versus sensor-capacitance change exhibits high accuracy. The conversion time and maximum nonlinearity are less than 100 and 24 ppm, respectively.
Keywords—Capacitive sensor , real-time measurement current conveyor, advanced RISC machine.

摘要 iv
誌謝 vi
目次 vii
表目錄 ix
圖目錄 x
第一章 緒論 1
第二章 各種電容性感測方法的比較 3
2.1 Ferry N. Toth 於1992年提出的電容性位置感測器 3
2.2 Ferry N. Toth 於1996年提出之電容性感測器 4
2.3 Manel Gasulla 於2003年提出的電容性感測器 7
2.4 本文和文獻的比較 9
第三章 訊號轉換技巧的探討 10
3.1 單斜率A/D轉換器 10
3.2 雙斜率A/D轉換器 11
3.3 類比至數位轉換的功能評估 12
3.3.1 解析度 12
3.3.2 轉換時間 13
3.3.3 量化誤差 14
第四章 訊號處理系統功能描述 16
4.1 轉移特性增益的推演 17
4.1.1 相位A 19
4.1.2 相位B 21
4.1.3 相位C 23
4.2 偏移電壓及寄生電容效應的消除方法 23
第五章 驅動程式 27
5.1 類比數位信號轉換 29
5.2 驅動程式的編寫方法 30
5.2.1 註冊動作 31
5.2.2 file 結構 33
5.2.3 open函數 34
5.2.4 Interrupt函數 38
5.2.5 Read( ) 宣告語法如下 40
5.2.6 Release( ) 42
5.3 在應用程式開啟驅動程式的功能 43
第六章 測試步驟及實驗結果 46
6.1 應用程式與驅動程式的建立與下載 46
6.1.1 建立應用程式 46
6.1.2 建立驅動程式 47
6.1.3 修改mkrd 49
6.1.4 製作新的NewLinux.bin 49
6.1.5 將NewLinux.bin檔燒錄至ARM的快閃記憶體 51
6.2 實驗結果 53
6.2.1 輸入訊號為正弦波 54
6.2.2 輸入訊號為鋸齒波 55
6.3 實驗測試結果 56
結論及參考文獻 60

[1]M. Lemkin and B. E. Boser, “A micromachined fully differential lateral accelerometer,” Proc. IEEE Custom Integrated Circuits Conf., 1996, pp. 315-318.
[2]T. J. Brosnihan, A. P. Pisano and R. T. Howe, “Surface micromachined angular accelerometer with force-feedback,” Proceedings of the ASMED &C Division, DSC-Vol. 57-2, 1995, pp. 941-7.
[3]Larry K. Baxter, “Capacitive sensors: design and applications,” IEEE Press, Piscataway, NJ, U. S. A., 1997, pp. 37-45.
[4]K. Martin, “A voltage-controlled switched capacitor relaxation oscillator,” IEEE J. Solid-State Circuits, vol. SC-16, Aug. 1981, pp. 412-414.
[5]A. Cichocki and R. Unbehauen, “A switched-capacitor interface for capacitive sensors based on relaxation oscillator,” IEEE Trans. Instrum. Meas., vol. 39, Oct. 1990, pp. 797-799.
[6]G. C. M. Meijer, J. van Drecht, P. C. de Jong and H. Neuteboom, “New Concepts for signal processors and their application to PSD’s,” Sensors and Actuators A, vol. 35, 1992, pp. 23-30.
[7]F. N. Toth and G.. C. M. Meijer, “A low-cost, smart capacitive position sensor,” IEEE Trans. Instrum. Meas., vol. 41, Dec. 1992, pp. 1041-1044.
[8]Ferry N. Toth, Gerard C. M. Meijer and Harry M. M. Kerkvliet, “A very accurate Measurement System for Multielectrode Capacitive Sensors,” IEEE Trans. Instrum. Meas., vol. 45, Apr. 1996, pp. 531-535.
[9]M. Gasulla, X. Li and G. C. M. Meijer, “A High-Speed Capacitive-Sensor Interface Using a relaxation oscillator and fast counter,” IEEE Instru. Measu. Technol. Conf., Vail, CO, U. S. A., May 2003, pp. 811-816.
[10]X. Li and Gerard C. M. Meijer, “A novel smart interface for voltage-generating sensors,” IEEE Trans. Instrum. Meas., vol. 47, no. 1, Feb. 1998, pp. 285-288.
[11]Joost C. Letters, W. Olthuis, P. H. Veltink and P. Bergveld, “A sensitive differential capacitance to voltage converter for sensor applications,” IEEE Trans. Instrum. Meas., vol. 48, no. 1, Feb. 1999, pp. 89-96.
[12]Analog Device Inc., U. S. A., “The data sheets of AD844.”
[13]D. Young, “A micromachined variable capacitor monolithic low-noise VCOs,” Solid-State Sensor and Actuator Workshop, Hilton Head, SC, June 1996.
[14]Earl W. Swokowski, “Calculus, 6th Edition,” PWS publishing Company, Boston, MA, U. S. A., 1994, pp. 764-767.
[15]Thomas L. Floyd and David Buchla, “Basic operational amplifiers and linear integrated circuits,” Prentice-Hall, Inc, 1999, pp. 450-457.
[16]牛德真, 周書碩，基本運算放大器及線性積體電路，臺北市:臺灣東華，1999.
[17]J. van Drecht, G. C. M. Meijer and P. C. de Jong, “Concepts for the design of smart sensors and smart signal processors and their application to PSD displacement transducers,” Digesr of Technical Papers, Transducers ’91.
[18]鄭慕德，嵌入式微電腦系統實習ARM與LINUX，臺北市:全華，民92年.
[19]徐千洋，LINUX C函式庫參考手冊，臺北市:旗標，民90年.