Stochastic resonance is known as a phenomenon where the SNR of a nonlinear system improves by adding a proper level of noise. To facilitate this phenomenon, this paper proposes a stochastic resonance ADC (SR ADC) based on a charge-redistribution CDAC. The proposed SR ADC utilizes the same architecture as a CDAC-based SAR ADC. The performance of the SR ADC is analyzed in detail to demonstrate its feasibility and advantage over the typical Nyquist ADC, which reveals that the SR ADC is useful to convert the weak input signal whose amplitude is comparable to the input-referred noise of the comparator.