a pulse generating circuit utilizes a drift step recovery transistor to apply power from a direct current power supply to a pulse forming network when a trigger pulse is applied thereto . the pulse forming network comprises a storage inductor connected in series with the transistor , a series connected separating diode and a drift step recovery diode which are connected in parallel with the storage inductor , a series connected pumping inductor and pumping resistor which together form a pumping circuit connected in parallel with respect to the separating diode , and a load resistor . current passed via the transistor increases in the storage inductor and the pumping inductor and is blocked by the separating diode to inject electron - hole plasma from the pumping inductor into the drift step recovery diode when the transistor is conducting . the transistor blocks current at the end of the trigger pulse , and the storage inductor reverses polarity to bias the separating diode into a conducting state to extract the plasma from the drift step recovery diode . the drift step recovery diode blocks current after the plasma has been extracted to switch current from the storage inductor into the load resistor to generate a pulse .