Discharge lamp ballast circuit with charge pump igniter

A circuit for igniting and operating a discharge lamp comprising:

• first and second input terminals for connection to terminals of a source of DC supply voltage,
• first and second output terminals for connection to a discharge lamp,
• an output capacitance coupled across the first and second output terminals,
• a first diode and a first switching element connected in a first series circuit across the first and second input terminals,
• a control circuit coupled to a control electrode of the first switching element to make it alternately conduct and non-conduct at a frequency (f),
• a second diode and a second switching element connected in a second series circuit to the first and second output terminals and with the second diode polarized so as to prevent discharge of the output capacitance via the second switching element when the second switching element is conducting, and wherein,
• an inductive element is connected in circuit so that, during lamp ignition, when the second switching element is non-conducting a charge current for the output capacitance flows via the second diode and the inductive element, and when the second switching element is conducting the inductive element supplies a further charge current to the output capacitance via the first diode and the second diode.