Design of current-fed push-pull resonant inverters for cold cathode fluorescent lamps

This paper presents the circuit design of current-fed push-pull resonant inverters for cold cathode fluorescent lamps (CCFL). The current-fed push-pull resonant inverter acts as a sinusoidal current source to drive the nonlinear CCFL loads. The sinusoidal current source may be implemented with a center-tapped transformer and an inductor, or with a general transformer and two inductors. Both designs exhibit the same zero-voltage switching behavior. However, due to simple and low cost, the self-excited push-pull resonant inverters with bipolar junction transistors suit the applications of CCFL drivers. This paper depicts the designs of inverter circuits, and demonstrates the analyses with simulations and experimental results.