互補式金氧半導場效電晶體影像感測器技術(I)-一種單一路徑讀取電路及其可程式增益放大器

Abstract

摘要: 由於互補式金氧半導體技術的進步,近年來互補式金氧半導體影像感測器已經受到廣泛的注意，主要的原因在於顧客對於微型化、低功率、低成本的需求。互補式金氧半導體影像感測器提供了整合超大型積體電路中各個系統在同一個晶片上的機會，並且減少了電路版上分離的電路元件數量，降低包裝成本。一個包含時序控制器，感測器陣列，訊號處理器，類比到數位轉換器，數位介面的單晶片照相機是可預期的。在標準邏輯電路電壓提供下，此單晶片照相機的功率消耗僅有數十毫瓦，因此非常適合在可攜式電子產品的應用上。 互補式金氧半導體影像感測器包含了三個重要部分：第一個是像素陣列，第二個是晶片內部的訊號處理，而第三個是可程式化增益放大器。互補式金氧半導體影像感測器運用在高解析度方面時，像素尺寸將會是一個關鍵，所以像素的結構與佈局的技巧變得相當重要。一種含有三個電晶體的主動式像素感測器的架構被採用來克服此問題。除此之外，一種用以消除製程上的變動所產生之雜訊的完全單一路徑的讀取電路將被採用。可程式化增益放大器則是用來產生彩色濾波器圖樣。 互補式金氧半導體影像感測器使用台積電0.25微米混合訊號互補式金氧半導體標準製程，操作在25百萬赫茲。

Abstract: Because of the progress in CMOS technology there has been a growing interest in CMOS image sensors recently. The major reason for this interest is the customer demand for miniaturized, low-power, and low-cost digital cameras. CMOS image sensors offer a great potential to integrate a significant amount of VLSI electronics on a single chip and reduce the discrete components and packaging costs. It is now straightforward to envision a single-chip camera that has integrated timing and control electronics, sensor array, signal processing electronics, analog-to-digital converter (ADC), and full digital interface. Such a camera-on-a-chip will operate with standard logic supply voltages and consume power measured in the tens of milli-watts. Therefore, the camera-on-a-chip is very suitable for portable electron ic product applications. The CMOS image sensor includes several important parts: the first part is pixel array, the second part is on-chip signal processing, and the third part is programmable-gain amplifier. The pixel size will be the key point for CMOS image sensors in high-resolution applications, so the structure and layout technique of the pixel become quite important. An active pixel sensor (APS) with three transistors is proposed to overcome the problem. Furthermore, a fully single-path readout circuit is proposed to reduce the noises come from the process variation. The programmable gain amplifier will be used to create color-filter-patterns. The CMOS image sensor uses the TSMC 0.25μm mixed signal CMOS standard process and operates at 25MHz.