6.5 A 25.2Mpixel 120frames/s Full-Frame Global-Shutter CMOS Image Sensor with Pixel-Parallel ADC

Abstract

CMOS image sensors with rolling shutters (RS) currently dominate the market for consumer cameras, particularly interchangeable lens cameras (ILCs). Despite their widespread use, conventional sensors with RS, such as [1], have limitations in image expression due to the distortion of moving objects, flicker effects, and flash bands. To address these issues, previous studies have proposed various global shutter (GS) technologies, including charge-domain GS [2]–[5] and voltage-domain GS [6]–[8]. While these technologies have been successfully implemented in broadcasting and industrial cameras, they have not yet met the image quality requirements for consumer cameras, especially ILCs, owing to dynamic range (DR) and random noise (RN) limitations. One promising technology that might achieve both single-exposure GS capability and the desired DR and RN characteristics is the pixel-parallel ADC [9]. In recent years, significant advances have been made in reducing the pitch of pixel-parallel ADCs through the implementation of stacked structures. However, the pixel resolution has been limited to approximately 2M pixels [10]–[14]. There are significant challenges in maintaining image quality and reducing power consumption for battery operation with tens of megapixels required for professional and high-amateur photographers.

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