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

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。

In order to improve the imaging duality 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 50 μm ×50 μm pixel area are designed and fabricated in a 0. 35 μm 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 1 mV and 11 effective bits. The proposed circuits realize the low-noise digital output of read-out circuits for ultraviolet focal plane arrays.