Abstract: The nonlinearity of RF Power Amplifiers (RFPAs) driven by the concurrent dual band modulation signal is more complex and significant, so there are new problems for linearizing a concurrent dual band RFPA. In this paper, the in fluences of the synchronicity between the low frequency band and the high frequency band to the linearization are studied. The generation method of synchronous concurrent double band RF signals is proposed for solving the problems concerned with out of synchronization while two frequency signals are loaded. The 1001 (two carriers in the middle is empty) CDMA2000 signal and a single carrier WCDMA signal are used as low frequency and high frequency band test signal respectively, which are used to stimulate the Doherty power amplifier with the peak power of 51dBm in the experiment. The experimental results demonstrated that digital predistortion method is unefficient for linearization if the modulated signals in the two bands are not synchronized. When the signals in the two bands are synchronized, the linearity of the concurrent dual band RF power ampli fier could be improved significantly by utilizing the memory polynomial (MP) predistortion.