AC-DC converter using VGS-multiplier circuit for LED lighting applications

A floating-voltage DC source is proposed for simple AC-DC conversion. A conventional V_GS-multiplier circuit is modified with an additional control current signal in order to achieve variable output voltage. By modulating this control signal, the output voltage can track the input one so that the difference between the input and output voltages can be maintained to be constant with respect to varying the rectified input voltage. The proposed circuit is easily adopted for driving a light-emitting diode (LED) string, which provides a cost-effective solution for LED lighting applications.