A Spectrum Aliasing-Free All Digital RF -PWM Transmitter Using Sine Wave Reference

Abstract

To reduce the complex implementation of existing spectrum aliasing-free all-digital radio frequency digital pulse width modulation (RF-PWM) in engineering, a novel RF-PWM all-digital transmitter (ADTx) architecture using sine wave as the reference signal is presented. Four pairs of mutually orthogonal sine wave groups are used as the reference signals of the I and Q quadrature differential PWM units respectively, delta-sigma modulator and digital predistortion are used to suppress modulation noise and spectral aliasing. As a result, alias-free pulse coding can be realized, and the even harmonic components are also suppressed. The feasibility of this novel RF-PWM ADTx is demonstrated, and the system performance is verified by Q PSK and 16QAM signals. Simulation and measurement results show that when compared with the existing RF-PWM ADTx which uses triangular wave as the reference signal, the in-band signal quality and modulation performance of the proposed scheme is similar, but the complexity is much lower.