| 摘要 |
A ballast circuit for a gas discharge lamp includes a d.c.-to-a.c. converter circuit with circuitry for coupling to a resonant load circuit, for inducing a.c. current therein. The converter circuit comprises a pair of switches serially connected between a bus conductor at a d.c. voltage and a reference conductor, the voltage between a reference node and a control node of each switch determining the conduction state of the associated switch. The respective reference nodes of said switches are connected together at a common node through which said a.c. current flows, and the respective control nodes of the switches are connected together. A gate drive arrangement is provided for regeneratively controlling the first and second switches. The arrangement comprises a feedback circuit for providing a feedback signal representing current in the load circuit; a coupling circuit including an inductor for coupling the feedback signal to the control nodes; and a first bidirectional voltage clamp connected between the common node and the control nodes. A second bidirectional voltage clamp is coupled across the inductor in such manner as to limit the positive and negative voltage excursions across the inductor.
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