In this paper, the possible impact of RF switching device ON resistance variation with drain supply voltage, Ron(VDD) characteristic, on polar transmitter distortion is considered. Using Pulsed I/V measurement results over a 15 W GaN HEMT, the deviation in the Vdd-to-AM modulation profile is estimated. System-level calculations, in the presence of gateto- drain capacitance contribution to carrier feedthrough, allow the evaluation of the secondary role of this dispersion effect