高密度模块化TDI CCD成像系统设计

Design of high density modularity TDI CCD imaging system

为提升遥感相机的高密度组装技术,采用厚膜集成电路技术设计了高集成度的TDI CCD成像系统,并对该成像系统中的具体设计做了详述。首先TDI CCD焦平面通过机械拼接方式拼凑成可复制的单元。然后,通过三极管射极跟随器增强CCD输出图像信号强度传送给模拟前端芯片LM98640中转换成14 bit的数字信号,再传给现场可编程门阵列芯片XC5VLX50T-1FFG1136C缓存和整合处理。最终,通过TLK2711高速LVDS输出芯片传输给数据采集卡并在计算机上成像。该成像系统中所有的驱动信号和处理时序都是通过现场可编程门阵列产生的,计算机可以通过RS422通信总线对成像系统进行控制和部分参数修改。该系统中的驱动电路和CCD二次电源电路采用厚膜集成电路技术设计,提高了系统的集成度。实验结果表明:整个系统基于厚膜技术,驱动电路PCB电路板减少了2/3的面积,同时采用了机电热一体化的设计,实现了相机的高密度组装。该系统总数据输出速度达到3.6 Gbps,饱和输出图像信噪比52.6 d B。

In order to improve the high density assembly technology of remote sensing camera, a high density TDI CCD imaging system was designed with multichip module technology. First, TDI CCD focal plane with mechanical splicing technology was made to a copied unit. Then, the output energy of CCD output image signals was improved by a transistor emitter follower, they were transmitted to the analog front-end chips. Then they were converted into the 14 bits digital signals. After that they were integrated and processed through field programmable gate array（FPGA）. In the end, through TLK2711 high-speed chip they were sent to data acquisition card on the computer. All the driving signals and processing signals of the imaging system were produced by the FPGA. The computer can control the imaging system and exchange the parameter through RS422 communication bus. The experimental results show that the area of driving layout cut down 2/3 than convention design. It realized the camera ′ s high density assembly adopting the design of the mechanical and electrical integration of heat. And the total data speed can reach 3.6 Gbps in this imaging system, SNR can reach 52.6 d B.