Mathematical Model and Reference Frequency Optimization for Digital Dual-Band Pulsewidth Modulation

In all-digital transmitter (ADT), pulsewidth modulation (PWM) is a popular pulse coding technique. This paper makes research on the PWM technique for dual-band ADT. Firstly, the mathematical model of the dual-band PWM signal is derived and then the frequency components of the modulated signal are analyzed. Based on the analysis, an algorithm is designed to find the optimal reference frequency to improve the quality of the modulated signal. The simulation results validate the effectiveness of the mathematical model. In addition, with the optimal reference frequency, the spurious-free bandwidths are significantly improved, and the maximum improvement of error vector magnitude (EVM) is 5.4353%.