A wireless power system has a wireless power transmitting device and a wireless power receiving device. The wireless power transmitting device may include an inverter configured to drive a resonant circuit and may further include a sinusoidal pulse-width modulation (PWM) signal generator configured to generate a corresponding sinusoidal PWM control signal. The inverter may have an input that receives the sinusoidal PWM control signal. The sinusoidal PWM control signal may exhibit a plurality of different pulse widths summing to the target duty cycle of the sinusoidal PWM control signal. Operated in this way, the wireless power transmitting device exhibits reduced harmonic distortions, which mitigates undesired radiated spurious emissions.