Optimal base-drive requirements for the high-voltage power switching transistor are given. These requirements are used to minimise switching stresses and the amount of switching-aid circuit energy to be recovered. A passive resonant recovery technique is analysed and employed to transfer stored switching-aid circuit energy into the load. Experimental results for a 600 V, 100 A, 100 kHz Darlington switching module incorporating 95% efficient switching-aid circuit energy recovery are presented.