腦部神經活動的綜合變化所產生之電訊號稱作腦電波(Electroencephalogram、EEG)。由於腦波和人類的意識活動有某種程度的對應，因而引起許多研究者的興趣。
腦電波在經過頭顱衰減後便的十分微弱，且容易受到市電等外來雜訊的干擾，因此量測上並不容易。由於腦波訊號十分微弱，而皮膚與電極間的阻抗也不小，為了降低負載效應對量測的影響，需要使用一個具有高輸入阻抗的系統。
一般電路都會受到零件誤差的影響而與原本設計上有所出入，在本系統中以陷波濾波器最容易受到影響，零件的誤差會使的陷波濾波器的效果大幅降低，所以希望以電路設計與調整可變電阻來改善零件誤差所造成的影響。
本研究設計一個應用於視覺又發電位之腦波人機介面的腦波量測系統，包含類比放大電路、低通濾波器、陷波濾波器及傳輸與電腦介面，頻寬在10Hz-50Hz，具有高增益，高輸入阻抗的特性，並且能調整可變電阻來改善零件誤差所帶來之問題，並加入無線傳輸系統使攜帶更方便。

The signal, compositive changes produced by cerebration, is called electroencephalogram (EEG). Researchers are interested in EEG because EEG relates consciousness of human.
After going though the skull, EEG signal is very weak. Moreover, it is easily interfered with noise. Therefore, it is difficult to measure. Furthermore, because the brain wave is very feeble and electrode-skin impedance is high, the measurement system should have high impedance to reduce the loading effect.
Due to the uncertainties of electric elements, circuits are not ideal, especially the notch filter. This study designs an effective circuit only by adjusting a variable resistance of the circuit.
This study proposes a brain wave measure and amplifier circuit for a visual evoked potentials (VEPs) brain computer interface (BCI) system. The proposed brain wave measurement system includes a preamplifier, a three order low pass filter (LPF), a two order high pass filter (HPF), a notch filter and a wireless transmission module. The designed circuit has not only high gain but also high input impedance. The system can adjust variable resistance to overcome the non-ideal situation of the circuit. In addition, the circuit combination with a wireless transmission module and battery makes the proposed system being portable.

[1]黃豪銘，醫用電子學，二版，高立圖書，台北縣，民國九十二年。
[2]E. M. Spinelli and M. A. Mayosky,” AC coupled three op-amp biopotential amplifier with active DC suppression”, IEEE Trans. Biomed. Eng., vol. 47, pp. 1616-1619, Dec. 2000
[3]E. M. Spinelli, R. Pallàs-Areny, and M. A. Mayosky, “AC coupled front end for biopotential measurements,” IEEE Trans. Biomed.Eng.,Vol. 50, pp. 391–395, Mar. 2003.
[4]Enrique M. Spinelli, N. H. Martínez, M. A. Mayosky and R.Pallàs-Areny, ” A novel fully differential biopotential amplifier with DC suppression” IEEE Trans. Biomed. Eng. vol. 51 pp. 1444-1448, Aug. 2004.
[5]M. S. Spach, R. C. Barr, J. W. Havstad, and E. C. Long, “Skin-electrode impedance and its effect on recording cardiac potentials,” Circulation, vol. 34, pp. 649-656, 1966.
[6]A. S. Berson and H. V. Pipberger, “Skin-electrode impedance problems in electrocardiography,” Amer. Heart J., vol. 76, pp. 514-525, 1968.
[7]J. C. Huhta and J. G. Webster, “60-Hz interference in electro- cardiography”, IEEE Trans. Biomed. Eng., Vol. BME-20, pp. 91–101, Mar. 1973.
[8]A. C. Metting-van Rijn, A. Peper, and C. A. Grimbergen, “High-quality recording of bioelectric events. part 1. interference reduction, theory and practice”, Med. Biol. Eng. Comput., Vol. 28, No. 5, pp. 389–397, Sep. 1990.
[9] A. C. Metting-van Rijn, A. Peper, and C. A. Grimbergen, “High-quality recording of bioelectric events. Part 2. Low-Noise, low-power multichannel amplifier design”, Med. Biol. Eng. Comput., Vol. 29, No. 4, pp. 433–440, Jul. 1991.
[10]M. Fernandez Chimeno and R. Pallas-Areny, “A comprehensive model for power line interference in biopotential measurements”, IEEE Trans. Instrum. Meas., Vol. 49, No. 3, pp. 535–540, Jun. 2000.
[11]B. Winter and J. Webster, “Driven-right-leg circuit design,” IEEE Trans. Biomed. Eng., vol. BME-30, pp. 62–66, Jan. 1983
[12]E. M. Spinelli, N. H. Martinez and M. A. Mayosky,” A transconductance driven-right-leg circuit” IEEE Trans. Biomed. Eng., vol.46 pp. 1466-1470, Dec. 1999
[13]吳東格，“個人電腦型腦電圖量測系統之研製”，國立台灣大學電機工程研究所碩士論文，民國八十六年。
[14]連怡仲，“數位腦波機系統之設計與研製”，國立台灣大學電機工程研究所碩士論文，民國八十七年。
[15]杜益昌，“多通道腦波機系統之設計與裝置”，國立台灣大學電機工程研究所碩士論文，民國八十八年。
[16](日)大熊輝雄，臨床腦電圖學，周錦華譯，五版，清華大學出版社 2005。
[17]朱迺欣，前塵往事腦醫學，遠流出版社，台北市，民國八十九年。
[18]盧明智，黃敏祥，“OP Amp應用+實驗模擬”，全華科技圖書出版， 民國八十四年。
[19]關尚勇，林吉合，“破解腦電波”，藝軒圖書出版社，台北市，民國九十一年。
[20]國立編譯館主編，吳進安等編著，神經診斷學，揚智文化，台北市，民國八十七年。
[21] Dobromir Dobrev, ” High-CMRR instrumentation amp works with low supply voltages” EDN, pp 88-90, Oct. 2003.
[22]何中庸，濾波器分析與設計，全華科技圖書出版，台北市，民國八十八年。
[23](日)遠坂俊昭著，測量電子電路設計-濾波器篇，彭軍譯，科學出版社，北京，2006。
[24]禹帆，無線藍芽技術，文魁資訊，台北市，民國九十年。
[25]黃進強 “交流耦合平衡增益之腦波量測系統”，國立中央大學電機工程研究所碩士論文，民國九十六年。
[26] W. J. Ross Dunseith and E. F. Kelly, “Multichannel PC-base data-acquisition system for high-resolution EEG”, IEEE Trans.Biomed. Eng., Vol. 42, No. 12, pp. 1212-1217, Dec. 1995
[27] R. Martins, S. Selberherr, and F. A. Vaz, “A CMOS IC for portable EEG acquisition systems”, IEEE Trans. Instrum. Meas., Vol. 47, No. 5, pp. 1191-1196, Oct. 1998
[28] 林能毅，“十六通道腦電波訊號擷取晶片之研製”，中原大學
醫學工程研究所碩士論文，民國九十一年。
[29] 柯立偉，“腦神經人機界面及應用” 國立交通大學電機與控制工程學系博士論文，民國九十六年