An electronic apparatus including an oscillator, a sampler, a phase detector, a phase rotator and a loop filter is provided. The oscillator generates a reference and an auxiliary clock signal offset by 90 degrees. The sampler samples an input data signal at each transition edges to generate primary sampled signals. The phase detector determines a phase difference of a data transition of the input data signal relative to a data-sampling edge. The phase rotator rotates the primary sampled signals and the reference clock signal according to the phase difference. The loop filter generates a control voltage to control the oscillator to vary phases of the reference clock signal and the auxiliary clock signal according to phase difference of the data transition relative to the rotated reference clock signal.