A 60-Frames/s CMOS Image Sensor With Pixelwise Conversion Gain Modulation and Self-Triggered ADCs for Per-Frame Adaptive DCG-HDR Imaging

CMOS image sensors (CISs) have been evolving rapidly in recent years, offering unprecedented imaging capabilities. For high-end mobile CIS products, high dynamic range (HDR) features are favorably desired. Among various HDR techniques, dual-conversion-gain (DCG)-based HDR imaging offers several advantages due to its high image quality and single-frame basis. For DCG-based HDR applications, however, current state-of-the-art CISs suffer from frame rate reduction and higher power consumption. In this article, we present an adaptive DCG-HDR imaging based on a CIS design with per-frame pixelwise conversion gain (CG) modulation and self-triggered analog-to-digital converters (ADCs). According to the scene to be captured, each pixel adaptively adjusts to its unique CG mode. With a single readout per frame and without image fusion, a proof-of-concept prototype CIS that operates in adaptive DCG-HDR mode achieves a 90.5 dB of dynamic range and a power figure of merit (FoM) of 9.9 nJ/frame
$\cdot$
pixel. Compared to DCG-HDR imaging, operating at 60 frames/s, the presented adaptive DCG-HDR imaging reduces CIS power consumption by 38% and enables single-frame pixelwise HDR imaging, which is suitable for future mobile CIS products.