Patent ID: 7990739

Claim:
A resonant power converter comprising: a capacitor and an inductive device developing a resonant tank; a first transistor and a second transistor coupled to switch the resonant tank; and a control circuit generating a first signal and a second signal to control the first transistor and the second transistor respectively; in which the frequencies of the first signal and the second signal are changed in accordance with a feedback signal for regulating output of the resonant power converter; and wherein the control circuit is further coupled to detect an input voltage of the resonant power converter, and a pulse width of the second signal is modulated in response to change of the input voltage; and the control circuit comprising: a feedback-input circuit coupled to the output of the resonant power converter to receive the feedback signal; an oscillator generating an oscillation signal in response to the feedback signal; an output circuit generating the first signal and the second signal in accordance with the oscillation signal; and a differential circuit coupled to input of the resonant power converter and the capacitor for generating a modulation signal; wherein the pulse width of the second signal is modulated by the modulation signal; and wherein the feedback-input circuit generates a charge current and a discharge current in response to the feedback signal, the charge current and the discharge current are coupled to the oscillator, the charge current determines an on time of the oscillation signal, and the discharge current determines the off time of the oscillation signal.