A converter includes a phase locked loop (“PLL”) unit which outputs a first frequency signal having a first frequency during a first period of one frame and to output a second frequency signal modulated to have a frequency corresponding to a pattern of an image signal during a second period other than the first period, a pulse width modulation (“PWM”) signal generator which generates a PWM signal according to the frequency of the frequency signal outputted from the PLL unit, and a voltage generator which outputs a driving voltage obtained by modulating an input voltage in response to the PWM signal to a voltage output terminal.