The structure of the Dry coefficients of a sine wave is analysed. A new accurate frequency estimator for a single sinusoid is proposed by using the information obtained from the phase of the DFT coefficents. Its performance is complemental with Rife algorithm. So that synthetic approach is proposed. The simulation results indicate that this approach is much better than the DFT and some other fast methods at the cost of double FFT which is far less than the MLE in computer time.