A Novel Multi-level RF-PWM Method for Selective Harmonic Elimination

To eliminate the selective harmonics of radio frequency pulse width modulation (RF-PWM) signals, a novel multi-level RF-PWM method for all-digital transmitters (ADTx) is proposed.This method compares the adaptive thresholds in real-time with the phase modulated signal, and controls the pulsewidth of the corresponding subpulses to make the selected harmonics cancel each other out and keep the weighted superposition of fundamental frequency components proportional to input envelope.Compared with the existing techniques, the proposed method can significantly relax the filtering requirements and improve the wideband performance of the ADTx.For the third harmonic elimination, the corresponding 5-level RF-PWM scheme is presented in this paper.Finally, the proposed scheme is verified by extensive simulations and offline measurements. © 2019, Chinese Institute of Electronics. All right reserved.