Integration of 555 temperature sensors into a 64 × 192 CMOS image sensor

In this work, a novel approach for measuring relative temperature variations across the active area of a CMOS image sensor itself is presented. 555 Image pixels have been replaced by temperature sensors pixels (Tixels) in the same pixel array layer. Both sensors, pixels and Tixels, utilize the same readout structure to obtain the data. This approach of measuring temperature variations in the pixel array can be used to compensate for dark signal non-uniformity. Measurements of dark current and temperature have been performed in a temperature range of −40 and 90 °C. Results show that pixels and Tixels are working by using the same readout system based on source followers and column amplifiers. The average dark current of the image sensor increases with temperature in the temperature range of −40 and 60 °C, and at the same time, Tixels show high linear response, having a temperature error less than 0.6 °C after a 1st order best curve fitting.