Techniques for detecting and correcting phase discontinuity of a local oscillator (LO) signal are disclosed. In one design, a wireless device includes an LO generator and a phase detector. The LO generator generates an LO signal used for frequency conversion and is periodically powered on and off. The phase detector detects the phase of the LO signal when the LO generator is powered on. The detected phase of the LO signal is used to identify phase discontinuity of the LO signal. The wireless device may further include (i) a single-tone generator that generates a single-tone signal used to detect the phase of the LO signal, (ii) a downconverter that downconverts the single-tone signal with the LO signal and provides a downconverted signal used by the phase detector to detect the phase of LO signal, and (iii) phase corrector that corrects phase discontinuity of the LO signal in the analog domain or digital domain.