生物醫療系統已行之有年，然而近年來，隨著積體電路製程的演進及人類對健康管理的需求日增，可攜式或植入式系統儼然成為此類系統中的顯學。其應用面相當廣泛：如治療帕金森氏症、癲癇、神經肌肉性疾病、中風、癱瘓、人工視網膜、矽耳蝸、腦科學、生理訊號監測看護等皆屬於其範疇。在這類植入式系統裝置中，最前端的電路即為生醫放大器。
　　生醫放大器位於陣列型電極之後，其作用在於將電極所讀取之微弱活動電位放大並濾波。本論文採用兩級式的架構，使功耗與雜訊在設計上的衝突降到最小。另外，由於電極與生物體液之接觸面會產生偏差電壓，因此在電容回授的路徑上使用電容及電阻形成高通濾波器，由於在先進製程下為達到極低的轉角頻率須使用的電阻相當巨大，因此此篇採用以電晶體實現之可調式偽電阻架構，同時達到節省面積、降低變異及可調式之效能。在近期的研究中，神經細胞間互相抑制及增強的行為越來越受關注，多通道的生醫放大器是必要的，但由於皮膚細胞對熱的忍耐度有限，功耗的限制成為一大考量，動作電位偵測器在多通道應用中在節省後端處理器及傳輸器資料量上成為不可或缺的電路區塊。本研究結合適應性閥值設定及雙閥值偵測技術作為系統中的動作電位偵測器，功率消耗僅12.65μW。
　　本論文透過TSMC 0.18μm之製程實現，量測結果顯示，神經訊號放大器之增益為50.4dB，可調式頻帶下，高通轉角頻率範圍為15Hz~436.9Hz，低通轉角頻率為317Hz~11kHz。輸入等效雜訊在20Hz至11kHz的頻帶內為4.96μV_rms，單個神經訊號放大器之功耗為7μW，NEF則為3.69。結果顯示，此系統相當適合用於植入式系統裝置。

Biological prosthetic system had developed for a long time. The progress in CMOS technology and increasing demand of health management make implantable system become a main stream. The application of such a system including Parkinson's disease, epilepsy, neuromuscular disorders, stroke, paralysis, artificial silicon retina, silicon cochlea, physiology signal monitor, etc.
　The neural amplifier amplifies and filters the indistinct signal after it is recorded by electrode array. For deceasing design trade-off between power and noise, a two-stage structure is used in this article. A balanced tunable pseudo-resistor is used to acquire local field potential (LFP) and action potential (AP) separately while rejecting unwanted offset voltage induced by tissue-electrode interface. In recent years, the research about interaction between neurons is more and more popular, the multi-channel neural amplifier is essential in this application. However, low power design is desirable, heat produced from the power-hungry chip can eventually injury the deep-skin cells. Action potential detector is usually a choice to reduce power consumption of processor and transmitter. The proposed AP detector combines dual-threshold technique to adaptive threshold setting circuit and only consumes 12.65uW.
　　The article is fabricated by TSMC 0.18um process.　The measurement results show that the system achieved input referred noise 4.96mVrms and noise efficiency factor (NEF)3,69 with mid-band gain of 50.4dB and power consumption of 7uW.　The bandwidth is highly tunable in the range of 15Hz-436.9Hz for high-pass corner and 317Hz-11kHz for low-pass corner. The results show that the proposed low-power, low-noise biomedical system is suitable for implantable device applications.

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