Outphasing systems utilize radio-frequency high-efficiency Power Amplifiers (PAs). Here we analyze impairment distortion as result of Signal Component Separator (SCS) that accounts for most of the nonlinearities in outphasing systems. Phase modulation is the general canonical form for the SCS process, which generates two constant envelope outphased signals by shifting the signal with an outphasing angle. The outphased signals experience a nonlinearity called bandwidth expansion when the modulated signal power is very low near zero region. The bandwidth expansion requires broadband components, which increase the complexity and cost of the system. Here a new parameter is defined in order to analyze this case, and it is named Average to Minimum Power Ratio (AMPR).