A Transmitter Architecture for Nonconstant Envelope Modulation

摘要

This paper presents a transmitter architecture which is less sensitive to power amplifier AM/AM and AM/PM conversions. Indeed, most radio communication standards employ non-constant envelope modulation such as in the 802.11 series. Owing to power amplifiers' nonlinearities, distortions on the modulations degrade the overall transmitter performance. As a consequence, linearization methods, such as envelope elimination and restoration, have to be employed. The architecture relies on the transformation of a nonconstant envelope modulation to a constant or switched one. This signal coding enables the efficient amplification of the signal without undergoing power amplifier distortions. The envelope variation is restored by bandpass filtering just after the power amplifier.