An image sensor with noise-reduction circuitry includes a pixel array, many analog-to-digital converters, and many correlated dual sampling units. The pixel array includes rows and columns of pixel cells. Each of the pixel cells converts light into analog electrical signal. Analog-to-digital converters convert the electric signals output from the pixel cells into digital signals. The correlated dual sampling units convert the digital signals and/or the electric signals into correlated dual sampling signals to denoise the output of the image sensor by subtraction from the analog content. An electronic device is also provided.