Offset and delay cancellation circuit for a switching DC-DC power supply

摘要

A control circuit of a switching DC-DC power supply includes a feedback circuit detecting an output voltage of the power supply to generate a feedback signal, an error comparator detecting an error between the output voltage and a design value of the output voltage, a control logic circuit generating a control signal according to the error for regulating the output voltage, and an offset and delay cancellation circuit generating an offset adjust signal according to the feedback signal and a second reference voltage for adjusting an offset of the error comparator to pull the output voltage toward the design value.

主权项

1. 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.