Abstract: This paper presents an analysis of a reconstruction filter in a switched mode power amplifier system. Doubly and singly terminated filters for current-mode class-S power amplifiers were analysed previously through analytical, numerical, and experimental approaches, and it was shown that only singly terminated filters can fulfil the requirements of current-mode switching amplifiers, owing to their constant input resistance over the pass-band. In this paper potential effects of the parasitic components in the actual filters and the filter termination are evaluated. The simulation and measurement results of current mode class-S power amplifier systems employing GaN HEMT MMICs are presented and critically analysed.