Patent ID: 8525505

Claim:
A PWM controller for a DC-DC voltage converter having at least one pair of high-side and low-side elements connected by a phase node and switched by a PWM signal to control an inductor current to charge an output capacitor to generate an output voltage, the PWM controller comprising: a synchronous-signal generator connected to the phase node, filtering out a high-frequency component of a phase-node voltage at the phase node to generate a first signal synchronous and out-of-phase with the inductor current; and a PWM comparator circuit connected to the synchronous-signal generator, generating the PWM signal according to the first signal and a feedback signal related to the output voltage; wherein the synchronous-signal generator comprises: a first low-pass filter connected to the phase node, generating a second signal synchronous and in phase with the inductor current; an error amplifier connected to the first low-pass filter and the PWM comparator circuit, receiving the second signal at a negative input terminal and a reference voltage at a positive input terminal to generate the first signal; and a second low-pass filter connected to the first low-pass filter and the error amplifier, filtering out an AC component of the second signal to generate the reference voltage.