已有研究指出，帕金森氏患者的腦波在其特定頻帶上(LFP、spikes)會有異於常人的訊號，藉由偵測此一異樣訊號並告訴內部刺激器做適當的電流刺激，將可抑制不正常腦波發生，對患者做進一步的診療。本論文研究的宗旨及為發展出一套高效能的前端架構，期待能整合於生醫訊號擷取系統。
在前端感測器中，為了擷取極低頻(~0.1Hz)的神經訊號，電路前端所加的DC block電容往往需要達到nano-farad等級，造成植入面積過大的難題，本論文採用了漏電流互補式的pseudo resistor架構，形成極高阻值的偽電阻，以60pF的輸入電容，達到0.1Hz的高通轉角頻率，克服大面積電容的問題。
在活體生物量測中，往往會有運動雜訊的干擾以及刺激器高壓破壞的問題，前者會造成感測訊號飽和，後者則會使輸入閘極被打穿，為了克服此問題，我們發展出了新型的感測器與消除器，能在200μs的時間把運動雜訊消除掉，重新讀出微小神經訊號，此外，運動雜訊消除器搭配PMOS diode的運作，提供了刺激器雙重的放電路徑，能有效阻絕刺激器的高壓破壞。
於前級放大器，低雜訊設計的部份，採用了電路設計技巧以及負載電流分流的方式，把0.1Hz到5kHz的輸入等效雜訊壓到4.04μV，NEF達到3.8。在訊號線性度上，巧妙安排可變增益放大器中的開關位置以及使用rail-to-rail的運算放大器，使得差動輸出訊號在1V的擺幅下，THD可達到0.086%，並大幅縮減了可變電阻的面積。最後，在輸出端加上了一組高頻寬與高slew rate的類比緩衝器，提供系統可做不同頻段訊號偵測的選擇。

Recently there are evidences to show that the over-active neural behavior in specific brain area may cause the syndrome of Parkinson’s disease. Continuous neural signal recording and proper electric stimulation has been clinical proven to be a
possible tool to alleviate the oscillation then calm down the tremble.
In order to capture extremely low frequency neural signals, the DC block capacitor added in front of the sensor would often be with nano-farad scale. This work uses the complementary leakage-balanced structure to form an ultra-high-resistance pseudo resistor for 0.1Hz highpass corner frequency with 60pF input capacitance. For in vivo measurement, recording system always suffer from motion artifact interference and high voltage damage caused by stimulator. The former will be large to saturate amplifier output ; the latter may break the thin gate oxide of input MOS. To overcome this problem, we develop a motion artifact fast recovery loop with the recovery time of 200μs. The PMOS diodes associated with input stage provide dual discharge paths, which can effectively reduce the high voltage damage caused by
stimulator.
By using low noise circuit design skills, input equivalent noise from 0.1Hz to 5kHz down to 4.04μV, and the NEF is 3.8. Thanks for rail-to-rail opamps insertion and smart arrangement for the position of switches in VGA, the THD is 0.086% even if the differential output swing reaching 1V. At output, a high bandwidth and slew rate analog buffer is added to program the LFP or spike mode for neural signal recording.

[1]A.-V. Nurmikko, J.-P. Donoghue, L.-R. Hochberg, W.-R. Patterson, Y.-K. Song, C.-W. Bull, D.-A. Borton, F. Laiwalla, S. Park, Y. Ming, and J. Aceros, “Listening to Brain Microcircuits for Interfacing With External World - Progress in Wireless Implantable Microelectronic Neuroengineering Devices,” Proceedings of the IEEE, vol. 98, no. 3, pp. 375–388, March 2010.
[2]A.-M. Lozano, J. Dostrovsky, R. Chen, and P. Ashby, “Deep brain stimulation for Parkinson’s disease: disrupting the disruption,” THE LANCET Neurology, vol.1, pp. 225-231, 2002.
[3]K. Nowak, E. Mix, J. Gimsa, U. Strauss, K.-K. Sriperumbudur, R. Benecke, and U. Gimsa, “Optimizing a RodentModel of Parkinson's Disease for Exploring the Effects andMechanisms of Deep Brain Stimulation,” SAGE-Hindawi Access to Research Parkinson’s Disease, 414682, 19pp, 2011
[4]J. Xu, R.-F. Yazicioglu, B. Grundlehner, P. Harpe, K. A.-A. Makinwa, and C.-V. Hoof, “A 160uW 8-Channel Active Electrode System for EEG Monitoring,” IEEE International Solid-State Circuits Conference, Feb. 2011
[5]N. Verma, A. Shoeb, J. Bohorquez, J. Dawson, J. Guttag, and A.-P. Chandrakasan, “A Micro-Power EEG Acquisition SoC With Integrated Feature Extraction Processor for a Chronic Seizure Detection System,” IEEE Journal of Solid-State Circuits, VOL. 45, NO. 4, April 2010
[6]J. Guo, J. Yuan, J. Huang, J. K.-Y. Law, C.-K. Yeung, and M. Chan, “32.9 nV/rt Hz 60.6 dB THD Dual-Band Micro-Electrode Array Signal Acquisition IC,” IEEE Journal of Solid-State Circuits, VOL. 47, NO. 5, May 2012
[7]W.-M. Chen, H. Chiueh, T.-J. Chen, C.-L. Ho, C. Jeng, S.-T. Chang, M.-D. Ker, C.-Y. Lin, Y.-C. Huang, C.-W. Chou, T.-Y. Fan, M.-S. Cheng, S.-F. Liang, T.-C. Chien, S.-Y. Wu, Y.-L. Wang, F.-Z. Shaw, Y.-H. Huang, C.-H. Yang, J.-C. Chiou, C.-W. Chang, L.-C. Chou, C.-Y. Wu, “A Fully Integrated 8-Channel Closed-Loop Neural-Prosthetic SoC for Real-Time Epileptic Seizure Control,” IEEE International Solid-State Circuits Conference, Feb. 2013
[8]J. Lee, H.-G. Rhew, D.-R. Kipke, and M.-P. Flynn, “A 64 Channel Programmable Closed-Loop Neurostimulator With 8 Channel Neural Amplifier and Logarithmic ADC,” IEEE Journal of Solid-State Circuits, VOL. 45, NO. 9, Sept. 2010
[9]Z.-Y. Wang, ”Design of a low-noise, low-power amplifier for multichannel neural recording,” master's thesis in NTHU, May 2014
[10]D. Buxi, S. Kim, N.-V. Helleputte, M. Altini, J. Wijsman, R.-F. Yazicioglu, J. Penders, and C.-V. Hoof, “Correlation Between Electrode-Tissue Impedance and Motion Artifact in Biopotential Recordings,” IEEE Sensors Journal, VOL. 12, NO. 12, Dec. 2012
[11]R.-R. Harrison, “A Versatile Integrated Circuit for the Acquisition of Biopotentials,” IEEE Cust. Integr. Circuits Conference, no. Cicc, pp. 115–122, 2007.
[12]R.-R. Harrison, and C. Charles, “A Low-Power Low-Noise CMOS Amplifier for Neural Recording Applications,” IEEE Journal of Solid-State Circuits, VOL. 38, NO. 6, June 2003
[13]S. Hong, S. Lee, T. Roh, and H.-J. Yoo, “A 46μW Motion Artifact Reduction Bio-Signal Sensor with ICA Based Adaptive DC Level Control for Sleep Monitoring
System,” IEEE Custom Integrated Circuits Conference, Sept. 2012
[14]R. Muller, S. Gambini, and J.-M. Rabaey, “A 0.013 mm2, 5 μW, DC-Coupled Neural Signal Acquisition IC With 0.5 V Supply,” IEEE Journal of Solid-State Circuits,
VOL. 47, NO. 1, Jan. 2012
[15]A. Tajalli, Y. Leblebici and E.-J. Brauer, “Implementing ultra-high-value floating tunable CMOS resistors,” ELECTRONICS LETTERS, Vol. 44, No. 5, Feb. 2008
[16]M.-T. Shiue, K.-W. Yao and C. S.-A. Gong, “Tunable high resistance voltage-controlled pseudo-resistor with wide input voltage swing capability,” ELECTRONICS LETTERS, Vol. 47, No. 6, March 2011
[17]J. Citakovic, I.-R. Nielsen, J.-H. Nielsen, P. Asbeck and P. Andreani, “A 0.8V, 7μA, Rail-to-Rail Input/Output, Constant Gm Operational Amplifier in Standard Digital
0.18μm CMOS,” NORCHIP Conference, Nov. 2005
[18]Y. Zhang, Q. Meng, Z. Wang and S. Chen, “Constant-gm Low-Power Rail-to-Rail Operational Amplifier,” IEEE Wireless Communications & Signal Processing, Nov. 2009