Spectral regrowth analysis in wideband polar architectures applied to software defined radio

Polar architectures offering good efficiency tend to be generalized to broadband standards with high Peak to Average Power Ratio and rigorous emission mask. Some well-known sources of spectral distortions as delay between phase and envelope paths and PA nonlinearities reduce the relevance of such technique. This paper analyses another drawback which is the spectral regrowth produced by filtering the phase signal and not the envelope signal that is done in an architecture based on a digital PA. Three kind of spectral distortions are observable. The first one is Adjacent Channel Leakage Ratio degradation due to spectral regrowth in adjacent channels depending on the oversampling ratio. The two other effects attenuate and enlarge the out-of-band images what could be used to alleviate the filtering requirements for wideband systems.