Patent ID: 6271633
Filing Date: 2001-08-07
Classification: H02M,H05B,Y02B

Abstract:
In an electronic ballast circuit for driving a gas discharge lamp from a mains voltage signal supply, a ballast bridge unit having an upper and lower signal line comprises:a storage capacitor coupled across said upper and lower bridge unit signal lines;an input converter bridge having at least two switches coupled in series at an input common terminal, wherein an upper switch of said input converter bridge is coupled to the upper signal line of the ballast bridge unit and the lower switch of said input converter bridge is coupled to the lower signal line of the ballast bridge unit;an output converter bridge having at least two switches coupled in series at an output common terminal, wherein an upper switch of said output converter bridge is coupled to the upper signal line of the ballast bridge unit and the lower switch is coupled to the lower signal line of the ballast bridge unit;reference voltage signal bridge having at least two switches coupled in series at a reference voltage common terminal, wherein an upper switch of said reference voltage signal bridge is coupled to the upper signal line of said ballast bridge unit and the lower switch of said reference voltage signal bridge is coupled to the lower signal line of the ballast bridge unit; anda high-frequency generator that is configured to alternately switch the at least two switches of the reference voltage signal bridge at a frequency that is substantially higher than a frequency of the mains voltage supply, so as to form a first differential voltage signal between said common input terminal and said reference voltage common terminal and a second differential voltage signal between said common output terminal and said reference voltage common terminal.