In a pulsed-bias arc ion plating system, the load voltage and current in the substrate circuit manifest oscillation behaviors. A simple analogous electrical circuit model is then constructed, which consists of a pair of capacitor and resistor connected in parallel. The output of the analogous circuit reproduces the oscillation profiles measured from experiments. Finally, plasma sheath theory is used to explain the capacitance characteristic of the plasma load. (C) 2003 American Vacuum Society.