A 5.94- μ m Pixel-Pitch 25.2-Mpixel 120-Frames/s Full-Frame Global Shutter CMOS Image Sensor With Pixel-Parallel 14-bit ADC

We present a 25.2-Mpixel, 120-frames/s full-frame global shutter CMOS image sensor (CIS) featuring pixel-parallel analog-to-digital converters (ADCs). The sensor addresses the limitations of conventional rolling shutters (RSs)—including motion distortion, flicker artifacts, and flash banding—while maintaining image quality suitable for professional and advanced amateur photography. A stacked architecture with 3- $\mu $ m-pitch Cu–Cu hybrid bonding enables more than 50 million direct connections between the pixel array and the ADC circuits. The pixel-parallel single-slope ADCs operate with a comparator current of 25 nA and use a positive-feedback (PFB) scheme with noise-bandwidth control using an additional 11.4-fF capacitor, achieving $2.66~e^{-}_{\mathrm {rms}}$ ( $166.8~\mu V_{\mathrm {rms}}$ ) random noise (RN) at 0-dB gain with an REF slope of 2161 V/s. The 5.94- $\mu $ m pixel pitch accommodates 30-bit latches designed under SRAM rules in a 40-nm CMOS process. Noise analysis reveals that in subthreshold operation, the dominant noise contributors are the comparator current, REF slope, and second-stage load capacitance. The sensor delivers 14-bit resolution, a 75.5-dB dynamic range (DR), and 120-frames/s operation at a power consumption of 1545 mW. A figure of merit of $0.083~e^{-}_{\mathrm {rms}}{\,}\cdot $ pJ/step is comparable to state-of-the-art RS sensors. These results demonstrate that pixel-parallel ADC technology can be scaled to tens of megapixels while preserving high image quality and energy efficiency, enabling motion-artifact-free imaging in battery-powered consumer cameras.