中文摘要：

基于512元X射线探测器读出电路，对传统可变增益放大器（VGA）电路的结构和内部运放进行了优化设计，使其具有了改进相关双采样（CDS）的功能，从而使得512元整体电路得到了优化。分析了改进型VGA的电路结构、工作原理，采用Chartered 0．35μm2P4MCMOS工艺对电路进行了仿真和流片。仿真及测试结果表明，改进型VGA模块可有效实现改进型相关双采样的功能，抑制了固定模式噪声的影响，具有低噪声（18．5nV@1MHz）、大宽带（44．9Mz），能够满足系统10bit精度的要求。以此为基础优化的前端读出电路功能正确，相对改进前的电路，面积可减小约51％，功耗降低了约27％。

英文摘要：

Based on 512 units X-ray detector read-out circuit, the structure and OPA of traditional variable gain amplifier （VGA） circuit was optimized, enabling it to have the correlated double sampling （CDS） function, the entire circuit was optimized. The circuit structure and operational principle of improved VGA are analyzed. The function simulation and the taped-out were fabricated with the 0.35 μm 2P4MCMOS technology of Chartered. The simulation and test results demonstrate that the improved VGA module can realize the correlated double sampling function effectively, suppress fixed pattern noise and obtain wide band with low noise, fully satisfying the 10 bit precision of system request. As to the optimized front-end read out circuit, the function proves correct, the area reduces by 51% and the power consumption drops by about 27% comparing with the unimproved circuit.