Adaptive Column-Wise Multi-Gain HDR CMOS Image Sensor for Single-Shot HDR Imaging

This paper presents a novel column-wise multi-gain high dynamic range (HDR) CMOS image sensor (CIS) designed to adapt dynamically to varying illumination conditions. The proposed CIS employs a dual ramp generator and column-parallel gain control to enable two-stage analog gain (AG) adjustments, achieving up to 256 unique column-wise gain patterns. Additionally, this study introduces an innovative image synthesis method, which allows for HDR implementation without any loss of image resolution during the synthesis process. This ensures that the sensor maintains high-resolution imaging quality while adapting dynamically to illumination changes. These innovations allow for fine-grained HDR image synthesis within a single frame, eliminating motion blur and supporting real-time performance in dynamic environments. By combining these features, the proposed approach achieves a balance between high adaptability and high-quality imaging, meeting the stringent requirements of modern machine vision systems. Fabricated using a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.11~\mu $</tex-math> </inline-formula>m CMOS process, the prototype CIS integrates a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1280\times 720$</tex-math> </inline-formula> pixel array, operates at 30 fps, and consumes 4.89 mW of power. The design achieved competitive figures of merit: 176.9 pJ/frame/pixel, 15.39 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{mV}_{\mathrm {rms}}\cdot $</tex-math> </inline-formula>pJ/frame/pixel, and 0.015 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{mV}_{\mathrm {rms}}\cdot $</tex-math> </inline-formula>pJ/frame/pixel/<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2^{\mathrm {N}}$</tex-math> </inline-formula>. The experimental results validate the effectiveness of the column-wise multi-gain HDR approach.