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摘要:
由于红外图像传感技术具备不受环境影响、目标识别度好、抗干扰能力强等优点而受到广泛关注,但随着红外焦平面集成度的提升,光电系统的动态范围、噪声和满阱之间的制约关系尤为突出。为解决弱光下噪声和强光下满阱容量的矛盾,在5T红外像素电路中,利用反型MOS电容在特定电压区间内电容值和电压的关系,使红外图像传感器积分电容从6.5 fF到37.5 fF自动变化,提出一种基于自适应积分电容的高动态像素结构,并基于55 nm CMOS工艺技术,在12 288×12 288像素规模的红外图像传感器中研究其性能参数。结果表明:5.5 μm×5.5 μm的小尺寸像素具有1.31 Me−的大满阱容量和可变的转换增益,噪声电子数小于0.43 e−,动态范围超过130 dB。
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关键词:
- CMOS红外图像传感器 /
- 自适应积分电容 /
- 高动态范围 /
- 大满阱容量 /
- 像素读出电路
Abstract:Infrared image sensing technology has received widespread attention due to its advantages of not being affected by the environment, good target recognition, and strong anti-interference ability. However, with the improvement of the integration of the infrared focal plane, the constraints among the dynamic range, noise, and full well capacity of the photoelectric system are particularly prominent. Therefore, in order to solve the contradiction between noise in low light and full well capacity in strong light, in the 5T infrared pixel circuit, the relationship between the capacitance value and voltage of the inverse MOS capacitor in a specific voltage interval was used to automatically change the integral capacitance of the infrared image sensor from 6.5 fF to 37.5 fF, and a highly dynamic pixel structure based on adaptive integral capacitance was proposed. Based on 55 nm CMOS process technology, the performance parameters of an infrared sensor with a 12 288 × 12 288 pixel scale were studied. The research results show that a small-size pixel of 5.5 µm × 5.5 µm has a large full well capacity of 1.31 Me−, and a variable conversion gain. The noise is less than 0.43 e−, and the dynamic range is more than 130 dB.
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表 1 C1、C2和C3的阈值电压
Table 1. Threshold voltage of C1, C2, and C3
MOS管类型 Vth/V C1 0.62 C2 0.40 C3 0.30 表 2 5T红外像素电路的后仿真性能参数
Table 2. Post-simulation performance parameters of 5T infrared pixel circuit
光电流/pA 线性度/% 转换增益/
(μV·(e−)−1)噪声
电子数/e−动态
范围/dB满阱容量/
Me−10~ 50 97.5 110~24.8 0.43~2.2 130~116 1.31 50 ~500 96.6 24.8~6.5 表 3 图像传感器的性能对比
Table 3. Performance comparison of image sensors
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