Voltage converting circuit and method thereof

Abstract

A voltage converting circuit including a power stage, a filter, a comparator, a first and a second feedback units. The power stage receives an input voltage and outputs the input voltage according to a duty cycle. The filter receives the input voltage to convert the input voltage into a current, and filters the current to obtain an output voltage. The first feedback unit amplifies a difference between a reference voltage and the output voltage to obtain an error voltage. The second feedback unit calculates the quadratic differential and integration of the output voltage to obtain a sensing voltage. The comparator compares the error voltage and the sensing voltage, and outputs a comparing result to adjust a duty ratio. Herein, a ripple of the output voltage is linearly proportional to that of the current, and DC divided voltage level of the output voltage is substantially equal to the reference voltage.