A method for generating fractional PWM pulses to drive an light emitting device includes generating multiphase clock signals using a multiphase PLL or DLL includes the steps of generating a plurality of phases of PWM pulses that correspond to a number of phases of the multiphase clock signals, selecting two or more phases amongst the plurality of PWM pulses, performing logic operations of the selected phases of PWM pulses to generate fractional PWM pulses, and generating a driving current using the fractional PWM pulses in a current source. The light emitting device is can be an LED display comprising an LED array having a plurality of channels and a plurality of scan lines. The driving current drives LEDs in one of the plurality of channels.