像素级数字化紫外焦平面读出电路的研究

Research on Pixel Level Digital Read-out Integrated Circuits for Ultraviolet Focal Plane Arrays

摘要:

为提高紫外焦平面组件成像质量, 提出了可用于紫外焦平面的像素级数字化读出电路结构。针对紫外信号微弱及焦平面探测器像素面积小的特点, 设计了基于电容反馈跨阻放大器(Capacitive Trans-Impedance Amplifier, CTIA)结构、模数转换器和锁存器的紫外焦平面像素级模数转换读出电路, 并给出了实现像素内模数转换的工作原理。详细讨论了像素内模数转换的实现方法, 各模块的设计要求及其具体实现, 并基于0.35μm DP4M CMOS工艺设计制造了面阵规模128×128、像素单元面积50μm×50μm的读出电路芯片。电路性能测试与成像实验表明: 电路的精度达到1mV以下, 有效位数达到11位, 实现了紫外焦平面读出电路的低噪声数字化输出。

Abstract:

In order to improve the imaging quality of ultraviolet focal plane arrays, the structure of digital read-out circuits for ultraviolet focal plane arrays is presented. For the ultraviolet weak signal characteristics and small pixel area of focal plane arrays, the pixel level digital read-out circuits for ultraviolet focal plane arrays are proposed, which are based on the capacitive trans-impedance amplifier circuit, an analog to digital converter and a latch. The working principle of the designed analog to digital converter is proposed. Design requirements and realization of each module are discussed in detail. The 128×128 pixel read-out circuits with 50μm×50μm pixel area are designed and fabricated in a 0.35μm four metal double poly CMOS process. A test system is set up for the performance test of the proposed circuits and imaging experiments. The experimental results show that the circuits have an accuracy of less than 1mV and 11 effective bits. The proposed circuits realize the low-noise digital output of read-out circuits for ultraviolet focal plane arrays.