5.7 A 132dB Single-Exposure-Dynamic-Range CMOS Image Sensor with High Temperature Tolerance

Dynamic range is becoming a key performance parameter for CMOS image sensors (CISs), especially for the surveillance and automotive fields. Several well-known multi-exposure methods are widely used to expand dynamic range (DR). However, those methods cause issues such as motion artifacts and light emitting diode (LED) flickering with the composite images. Therefore, the single-exposure method is critical to the quality of high-DR images. The most obvious way to expand single-exposure DR is by employing in-pixel capacitors. One of the most well-known technologies with in-pixel capacitors is the lateral overflow integration capacitor (LOFIC), which is characterized by a unique signal read-out method for in-pixel capacitors [1], [2]. Also, a CIS that uses an organic-photoconductive-film and an in-pixel capacitor is reported in [3]. Spatial sampling with sensitivity ratio is another common method to expand single-exposure DR [4]. However, assuming practical resolution, the LOFIC technology or spatial sampling with sensitivity ratio can achieve less than 100dB single-exposure DR. A method combining spatial sampling with sensitivity ratio and an in-pixel capacitor is also presented in [5] to expand its single-exposure DR. This sub-pixel architecture can achieve over 120dB single-exposure DR. But another challenge arises: at high temperature, the degradation in signal-to-noise ratio (SNR) at the composite boundary become significant. In this work, we present a prototype of 5.4Mpixel stacked back-illuminated CIS using the sub-pixel architecture with high-temperature tolerance.