陣列型電流式生物感測器前端讀出電路積體化設計與實現

本論文針對陣列型電流式生物感測器的前端讀出電路進行分析與設計。利用陣列型讀出電路能一次讀取多筆感測器訊號，最重要的是結合陣列型感測器可以提高訊號雜訊比。感測器方面，先利用市售血糖測試儀找出信號電流大小(0.7u∼14uA)、感測器阻值(22K~390K )與濃度(31∼550mg/dl)之關係。此數據為依據建構電流式感測器等效電路。電路架構上，運算放大器採用摺疊式架構。以運算放大器結合回授電阻完成轉阻放大器，利用轉阻放大器將微小的電流訊號放大並轉換為電壓訊號。後端再以類比多工器選取所需之電壓訊號，類比多工器為外部數位輸入訊號所控制。此電路架構有助於縮小電路之面積。另外也針對類比多工器開關不理想效應、感測器阻值和雜訊之關係、電路之雜訊做實際量測和模擬分析。吾人利用SPICE來模擬電路，且利用市售晶片電路做量測驗證。其電路採用國家晶片中心(CIC) TSMC 0.35um 2P4M CMOS製程製作。

關鍵字

轉阻放大器；類比多工器

並列摘要

In this thesis, we designed and analyzed front-end readout circuit for linear-array amperometric biosensor. The front-end readout circuit can acquire a large number of sensor signals at one time and can raise signal-to-noise ratio (SNR) when it combines with linear-array sensor. We used commercial blood glucose meter to find the relation between the ranges of current response (0.7u∼14uA), sensor resistance(22K~390K ) and concentration measurement(31∼550mg/dl). Then, this data was used to build amperometric biosensor equivalent circuit. In the circuit architecture, the amplifier used Folded Cascode structure. The amplifier was integrated with feedback resistance to accomplish transresistance amplifier and the tiny signal current was amplified and changed into signal voltage. At the back of transresistance amplifier was Analog Multiplexers that was used to select signal voltage and is controled by output digital signal. This circuit architecture could reduce circuit area. Besides, the measurement and simulation was done to analysis the not ideal effect of analog multiplexer switch, the relation between sensor resistance and noise, and the circuit noise. We used SPICE to simulate the circuit and used discrete circuit for testing and verification. The circuits were fabricated by using TSMC 0.35um 2P4M CMOS process.