A method for controlling a lighting system includes detecting a phase angle of a rectified input signal, determining a current shaping signal using the detected phase angle, and adjusting the rectified input signal in response to the current shaping signal. A circuit for controlling a lighting system includes a phase angle detector detecting a phase angle of a rectified input signal and generating a phase angle signal indicative of the phase angle, and a current shape controller determining a current shaping signal using the detected phase angle and a scaled input signal and adjusting the rectified input signal in response to the current shaping signal.