Abstract: An electronic ballast suitable for lighting control for a fluorescent lamp which includes a bridge rectifier for rectifying input commercial power supply voltage and a high frequency oscillator for feeding the fluorescent lamp a high frequency supply voltage, wherein the electronic ballast further comprises a linear active switching mode filter circuit for filtering the output of bridge rectifier by a linear active switching mode and feeding a supply voltage to the high frequency oscillator. With such configuration, the electronic ballast can be combined with a conventional thyristor lighting controller.

Abstract: A high power factor electronic ballast for fluorescent lamps having low lamp current peak ratio and which includes a bridge rectifier for rectifying a commercial power supply voltage, a high frequency oscillator using an output voltage from a bridge rectifier as its supply voltage, a first supplementary power source to supply the high frequency oscillator a voltage by superimposing two supplementary voltages generated from a portion of high frequency current in a load on the output voltage from the bridge rectifier, and a second supplementary power source to supply the high frequency oscillator a direct offset voltage generated from a portion of high frequency current in the load to improve the input current waveform of the bridge rectifier.