The Effect of Unequal Time of Rising and Falling Edge on Three Level RF-PWM Signal

This paper analyzes the performance of RF-PWM signal when the time of rising and falling edge is not equal. Firstly, the reason of unequal edge time is analyzed and modeled for three level pulse signals. The influence is divided into amplitude and phase distortion. Secondly, the influence of unequal time of rising and falling edge is analyzed by fast Fourier transform (FFT). Then the phenomenon of pulse swallow caused by rising and falling time is discussed. Finally, MATLAB is used to simulate and analyze the changes of the output signal in-band and out-of-band performance. Theoretical analysis and simulation results show that, the Error Vector Magnitude (EVM) and Adjacent Channel Power Ratio (ACPR) of the signal will deteriorate obviously when the time of the rising and falling edge is not equal. Moreover, the impact of pulse swallow on the signal performance is limited, when the input signal is a high peak-to-average power ratio (PAPR) signal.