一种高灵敏度大动态范围的红外焦平面异形读出电路的设计

Design of An Infrared Focal Plane Special Shaped Readout Circuit with High Sensitivity and Dynamic Range

摘要:

针对短波红外焦平面探测器高灵敏度、大动态范围的发展需求,设计了一款新型的红外焦平面异形读出电路。传统的像元只使用一种输入级,难以兼顾高灵敏度和大动态范围,而在该设计中包含的组合像元使用了CTIA和大动态范围两种输入级,兼顾了其优点。具体布局为每2×2个CTIA输入级模块阵列中间,含有1个直接注入模式/对数模式可切换的大动态范围输入级模块。工作模式有两种,第一种为CTIA输入级模块和直接注入模式的大动态范围输入级模块同时工作；第二种为CTIA输入级模块和对数模式的大动态范围输入级模块同时工作。基于0.18μm 3.3V标准CMOS工艺,绘制了CTIA输入级阵列规模为320×256,像元中心距为15μm的异形电路像元阵列版图。仿真结果表明,异形电路像元通过小积分电容实现了高灵敏度,通过对数光响应输出实现了大动态范围。

Abstract:

We designed a new type of infrared focal plane readout circuit with combined pixels to meet the development requirements of both high sensitivity and high dynamic range. The designed circuit can be used for shortwave infrared focal plane detector arrays. Traditional pixels typically use only one input stage, which makes it difficult to balance high sensitivity and high dynamic range. In contrast, combined pixels use a capacitive trans-impedance amplifier (CTIA) input stage along with a high dynamic range input stage, thereby inheriting their advantages. The specific layout of a combined pixel contains one high-dynamic-range input stage located in the middle of every 2×2 CTIA high-sensitivity input stage. This high dynamic range input stage can be switched between direct injection and logarithmic modes. We realized the layout of a 320×256 readout circuit for combined pixel arrays with a 15μm pitch using a 0.18μm 3.3V standard CMOS process . Simulation results show that both high sensitivity and a high dynamic range can be achieved using small integral capacitors and a high dynamic range in combination with the logarithmic mode.