In an inventive photonic analog-to-digital signal converter (ADC), multiple opto-electric sampling devices are employed to successively sample an analog signal input. Optical clock signals having the same frequency but different clock phases are used, which are associated with the opto-electric sampling devices, respectively. Each sampling device takes samples of the analog signal input in response to the optical clock signal associated therewith. The resulting samples are processed to produce quantized samples. The inventive ADC outputs a digital signal representing the quantized samples.