A 50.1-Mpixel 14-Bit 250-frames/s Back-Illuminated Stacked CMOS Image Sensor With Column-Parallel kT/C-Canceling S&H and ΔΣADC

This article presents a 50.1-Mpixel 14-bit 250-frames/s back-illuminated stacked CMOS image sensor on 35-mm optical format exhibiting 1.18- $\text{e}^{-}$ rms random noise at 0 dB. This sensor employs a load reduction technique by splitting half of pixel signal line using a Cu-Cu connection technology underneath the pixel area, pipelined operation with a gain-adaptive column-parallel kT / $C$ noise-canceling sample and hold, and a 250-frames/s scanning rate and 14-bit resolution delta-sigma analog-to-digital converter (ADC) circuit. Moreover, an on-chip online calibration of column mismatch maintains the non-linearity of the output image within −0.42%. As a result, FoM6 ( $\text{e}^\ast $ pJ/step) of 0.09 is obtained as the state-of-the-art performance.