Abstract: The invention relates to circuits and methods that that reduce or eliminate the second harmonic ripple in the output of a single stage AC-DC converter, while minimizing the required output capacitance. The circuits and methods include an average current modulator having a switch connected in series with the DC load, and strategies for sampling the load current and controlling a duty cycle of the switch by comparing the sampled current to a current control signal so that the average load current is maintained at a selected current, and the second harmonic ripple component of the load current is reduced or eliminated. The circuits and methods substantially improve the performance and reliability of single stage AC-DC converters. The circuits and methods are particularly useful in applications were low ripple and high reliability are desirable, such as in driving LED loads in lighting applications.