Abstract: An electronic ballast is provided for converting an AC voltage and current, supplied by a power source such as a power line, to an alternating square-wave voltage and current having the same frequency, for supply to a discharge lamp. The ballast includes at least one capacitor, bridge switches and high-frequency duty-cycle switches. The bridge switches and the high-frequency duty-cycle switches cooperate to successively electrically connect the capacitor in parallel with the power source, electrically connect the capacitor in series with the power source and the discharge lamp, and to regulate the current provided to and from the capacitor to drive the discharge lamp with a desired square-wave voltage and current at the line frequency.

Abstract: An electronic ballast for a discharge lamp includes a capacitive storage device which is serially connected with an AC power source and the lamp. A first combination of switches, arranged in a bridge configuration, alternately reverse the polarity in which the capacitive storage device is connected. A second combination of switches periodically bypasses the capacitive storage device and momentarily places the AC power source directly in series with the lamp.

Abstract: A high power bipolar transistor device includes an integral antisaturation Schottky diode resulting from direct contact between the metallic base electrode and the collector region of the transistor. The barrier height of the Schottky diode is chosen so that it turns on at a slightly lower voltage than the collector-base voltage at saturation and diverts excess drive current away from the base to prevent the transistor from becoming fully saturated. The integral Schottky diode may also be used to prevent latch-up in a thyristor device or in a parasitic thyristor which forms part of an insulated gate transistor.