Structure of highly dynamic pixel based on adaptive integral capacitance

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.