A driving voltage provider includes: a PLL circuit for generating clock signals with different phases according to a divider value; a DC-DC converter for generating a PWM signal according to the frequency of a first clock signal, and providing a driving voltage based on the duty ratio of the PWM signal; a first tuning circuit for outputting a first tuning signal having a first logic level when the logic levels of first and second sampling signals obtained by sampling the PWM signal at transition times of different clock signals are different, and outputting the first tuning signal having a second logic level when the first and second sampling signals have the same logic level; and a divider value determiner for decreasing the divider value when the logic level of the first tuning signal is the first logic level.