Abarca Accel, Theuwissen Albert
EWI Faculty, Electronic Instrumentation Laboratory, Delft University of Technology, Mekelweg 4, 2628 CD Delft, The Netherlands.
Now with the International Iberian Nanotechnology Laboratory, Avenida Mestre José Veiga s/n, 4715-330 Braga, Portugal.
Sensors (Basel). 2023 Nov 10;23(22):9109. doi: 10.3390/s23229109.
This paper presents a novel technique for dark current compensation of a CMOS image sensor (CIS) by using in-pixel temperature sensors (IPTSs) over a temperature range from -40 °C to 90 °C. The IPTS makes use of the 4T pixel as a temperature sensor. Thus, the 4T pixel has a double functionality, either as a pixel or as a temperature sensor. Therefore, the dark current compensation can be carried out locally by generating an artificial dark reference frame from the temperature measurements of the IPTSs and the temperature behavior of the dark current (previously calibrated). The artificial dark current frame is subtracted from the actual images to reduce/cancel the dark signal level of the pictures. In a temperature range from -40 °C to 90 °C, results show that the temperature sensors have an average temperature coefficient (TC) of 1.15 mV/°C with an inaccuracy of ±0.55 °C. Parameters such as conversion gain, gain of the amplifier, and ADC performance have been analyzed over temperature. The dark signal can be compensated in the order of 80% in its median value, and the nonuniformity is reduced in the order of 55%.
本文提出了一种新颖的技术，用于在-40°C至90°C的温度范围内，通过使用像素内温度传感器（IPTS）对CMOS图像传感器（CIS）进行暗电流补偿。IPTS利用4T像素作为温度传感器。因此，4T像素具有双重功能，既可以作为像素，也可以作为温度传感器。因此，可以通过根据IPTS的温度测量结果和暗电流的温度行为（先前已校准）生成人工暗参考帧来在本地进行暗电流补偿。从实际图像中减去人工暗电流帧，以降低/消除图像的暗信号电平。在-40°C至90°C的温度范围内，结果表明温度传感器的平均温度系数（TC）为1.15 mV/°C，误差为±0.55°C。已对温度范围内的转换增益、放大器增益和ADC性能等参数进行了分析。暗信号的中值可以得到约80%的补偿，不均匀性降低了约55%。
