A power supply provides dc power over a wide range of output voltages at full operating power by utilizing multiplying circuits (200) supplied by a source of high-frequency alternating current (90). The multiplier circuits include a plurality of multiplier cells containing at least two diodes (207, 209) and a driving capacitor (208). The multiplier cells are shunted by bypass rectifiers (205, 206) arranged such that currents are allowed to flow from multiplier input terminals to power supply output terminals. The bypass rectifiers do not conduct current for low output current levels, but conduct increasing levels of current when output currents increase beyond a conduction threshold value, thereby increasing the maximum available output current. Interactions among the diodes and capacitors in the multiplier circuits cause the amplitudes of the multiplier input currents to remain relatively constant as the output voltage is varied while operating at full power.