新型室溫下紅外線偵測器陣列之互補式金氧半影像讀出積體電路設計與分析

Abstract

為了降低製造成本以應用於消費性產品，以微機械結構技術所製造的新型熱阻式紅外線偵測器已經發展出來了。與過去所常用的光電子式紅外線偵測器不同的是，熱阻式紅外線偵測器可工作在室溫下而不需要昂貴的冷卻器，但其主要的缺點則是較小的紅外線靈敏度與較大的背景直流訊號。因此紅外線讀出電路的關鍵技術在於如何消去背景直流訊號後以最小失真地讀出紅外線信號。 過去的所發表的讀出電路的主要架構大致上可分為三類，定電流式､定電壓式與定偏壓式。這三類架構都各有其優缺點，在本論文中，這三類的架構都已被分析､設計並下線製造，製作的晶片也已經完成量測，量測結果也符合分析的結果。在這三類架構中，定電流式架構具有眾多優點，因此被選為讀出電路的主要架構，並且用於下線製作64×64像素的二維影像讀出電路。 在定電流式的架構中，為了配合後級的電流積分讀出級以消除雜訊，提高讀出電路的效能，我們採用了一電壓對電流轉換器將前級偵測器所產生的電壓變化轉為電流訊號。在這個轉換的過程中，電壓對電流轉換的線性度直接的影響到了訊號讀出的效能，因此我們提出了一個用於讀出熱阻式紅外線偵測器訊號的新型電壓對電流轉換器，命名為定電流式緩衝直接注入，其具有高轉換線性度與低偏移度。此外，為了增加訊號的動態範圍，使用了臨界電壓補償式電流源技術的電流式背景壓抑電路。為了降低固定樣本雜訊，相關雙取樣電路技術被應用在輸出級。 以點五微米DPDM n-well製程互補式金氧半技術設計並製造的二維影像讀出電路也已經完成量測，量測的結果為81.30%的均勻度與85.92%的線性度，功率消耗約為150mW。未來將以提高均勻度､提高線性度與降低功率消耗為努力的目標。

The new bolometer IR detector based on the micromachining structure technology has been developed to reduce the cost for commercial applications. The difference between the bolometer and the past photon IR detector is that the bolometer IR detector can operate at a room temperature without an expensive cooling system. But the major disadvantages are the smaller IR sensitivity and the larger background DC signal. Hence the key technique of the IR readout circuits is the elimination of the background DC signal to read out IR signal with minimal distortions. In the past, the readout circuits may be divided into three configurations: Constant Current (CC), Constant Voltage (CV) and Constant Bias (CB). Each of these configurations has its advantages and disadvantages. In this thesis, all of these configurations have been analyzed, designed and taped out. The fabricated chip has been measured. The measurement results also confirm the analysis. Among the three configurations, CC configuration has the most advantages and is used to compose the 64×64 pixels two-dimensional readout circuit. In CC configuration, a transconductor amplifier has been presented to translate the voltage variation caused by the detectors to the current signal, which is used to eliminate the noise in the integration capacitor stage. During the transformation, the linearity of the transconductor amplifier dominates the readout performance. Hence a new transconductor amplifier, named Constant Current Buffered Direct Injection (CCBDI), has been purposed for bolometer IR detectors with a high linearity and a low offset. Further, a current-mode background suppression based on the threshold-voltage compensated current source has been presented to increase the signal dynamic range. A correlated double sampling (CDS) technique has been used to reduce the fixed pattern noise at output stage. A 64×64 pixels two-dimensional readout circuit, which is designed and fabricated by 0.5mm Double-Poly-Double-Metal (DPDM) n-well CMOS technology, has been measured. The measurement results show the uniformity of 81.30%, the linearity of 85.92% and the power dissipation closed to 150mW. In the future, to increase the uniformity, to increase the linearity, and to reduce the power consumption are the important researches.