An EER Transmitter Architecture with Burst-Width Envelope Modulation based on Triangle-Wave Comparison PWM

Abstract

High efficiency transmitter architecture based on Kahn envelope elimination and restoration using PWM envelope modulation schemes is studied. At the final stage, it modulates a constant envelope radio frequency signal by on-off keying or "burst width modulation" directly with the PWM or delta-sigma modulated envelope signal without a lowpass filter. This paper shows that it is suitable to use a triangle-wave comparison PWM which has coherent spectrum peaks of spurious due to switching. It is derived from theoretical analysis that the minimum switching/sampling rate is required as five times high as the baseband bandwidth that is much less than that for the delta-sigma modulation. Simulation results show good modulation quality with the EVM less than 1 percent for raised cosine roll-off filtered 64 QAM.