Non linearities modelling method influence in High Power Amplifier on the CDMA spectral analysis

The radio frequency ressource utilization in mobile communication requires more efficient modulation and multiple acces scheme. The CDMA with spread spectrum signal has been adopted in few wireless communications systems. But as in other system, the most critcal components is the High Power Amplifier. Firstly, the target of this paper is to provide an comparative analysis, based on co-simulation circuit/system of an MMIC power amplifier. Most of systems use nonconstant envelope modulations, to achieve a high degree of spectral efficiency, but those modulations are more sensitive to the non linearities of the circuits. So in the second part, for an TDMA scheme test the performances of differents modulations, by calculating the Adjacent Channel Power Ratio and the Error Vector Measurement.