How to reach 100% coding efficiency in multilevel burst-mode RF transmitters

Among other goals, multilevel burst-mode radio frequency (RF) transmitters have to achieve two main objectives: high efficiency, and good transmission signal quality. Both of these goals depend, to a large extent, on the driving signal modulator, which can, for example, be a digital pulse-width modulator. However, conventional digital pulse-width modulation (PWM) contains aliasing distortion that prevents achieving satisfying transmission signal quality. In this paper, an aliasing-free digital multilevel PWM method is introduced that allows for achieving good transmission signal quality, while at the same time offering the potential of reaching a coding efficiency of 100%. The mathematical equations for aliasing-free digital PWM are extended in a way that makes them suitable for the use in multilevel burst-mode RF transmitters. It is then shown how the aliasing-free multilevel PWM method can be used to achieve 100% coding efficiency. Simulations demonstrate the performance capabilities of the proposed PWM method.