JSSC 2006第7期Image Sensors

A High Dynamic Range Current-Mode Ampliﬁer for Computed Tomography

一种用于计算机断层扫描的高动态范围电流模式放大器

17位动态范围，噪声低于3pA，非线性度低于2%，信号带宽高于10kHz

计算机断层扫描电流模式放大器高动态范围像素级设计低噪声

▸创新点1：高动态范围电流模式检测器（系统创新）。该设计实现了17位动态范围，显著提升了CT成像系统的信号捕捉能力，解决了传统电压模式放大器在宽动态范围信号处理中的局限性。

▸创新点2：像素级调节电流镜结构（电路创新）。采用局部反馈机制优化电流镜线性度，将非线性误差控制在2%以内，同时支持10kHz以上带宽，适用于高速CT信号采集场景。

▸创新点3：亚3pA噪声地板设计（电路创新）。通过低噪声偏置电路和版图优化技术，实现超低噪声性能，为微弱X射线光子电流检测提供关键技术保障。

▸创新点4：单片集成工艺创新（工艺创新）。在标准CMOS工艺中同步集成光电二极管与电流放大器，避免了传统混合集成方案的封装寄生效应，提升系统可靠性。

Abstract

In this paper, we show a high dynamic range current- mode detector for computed tomography application. A regulated current mirror structure has been implemented at pixel level that provides with 17 bits dynamic range and a noise ﬂoor below 3 pA /82/77/83. Nonlinearity is kept below 2% and signal bandwidth is higher than 10 kHz. A test structure with 4 4 pixel array is pre- sented is this paper. Both photodiode and current mode ampliﬁer have been integrated into the same CMOS standard process.