A novel digital predistortion technique for class-E PA with delay mismatch estimation

This paper proposes a polynomial-based adaptive digital predistortion (DPD) method with delay mismatch estimation for the class-E power amplifier (PA), which can compensate the AM-AM and the strong AM-PM distortion produced by the switching operation of class-E PA. On the other hand, due to the strict requirement of timing alignment in polar transmission, a low-complexity correlation-based scheme for delay mismatch estimation and compensation filter is developed. Simulation results confirmed that the proposed DPD can improve the EVM performance from 5.67% to 0.72%, leading also to 18 dB rejection of spectrum re-growth under the condition of perfect timing alignment. The results also reveal that our proposed method of digital predistortion with delay mismatch estimation, as well as delay mismatch compensation has 1% EVM improvement as compared with applying DPD method directly without timing alignment.