A semiconductor device and a method for controlling amplitude of signal in the semiconductor device are provided. The semiconductor device comprises a signal generator configured to output a sinewave, a comparator configured to compare a magnitude of the sinewave with a magnitude of a reference signal at a first timing corresponding to a timing control signal and to output a comparison result, and a control signal adjustor configured to adjust one of the current control signal and a timing control signal depending on the comparison result of the comparator.