Patent ID: 8791678

Claim:
A control circuit of a switching DC-DC power supply having an output terminal for providing an output voltage, the control circuit comprising: a feedback circuit connected to the output terminal, detecting the output voltage to generate a feedback signal; an error comparator connected to the feedback circuit, comparing the feedback signal with a first reference voltage to generate a comparison signal; a control logic circuit connected to the error comparator, generating a control signal according to the comparison signal for the power supply to regulate the output voltage; and an offset and delay cancellation circuit connected to the feedback circuit and the error comparator, generating an offset adjust signal according to the feedback signal and a second reference voltage for adjusting an offset of the error comparator; wherein the offset and delay cancellation circuit comprises: an error transconductor connected to the feedback circuit, generating an error current according to a difference between the feedback signal and the second reference voltage; and a sample-and-hold circuit connected to the error transconductor and the error comparator, sampling and holding the error current to generate the offset adjust signal.