Abstract: A voltage converter includes a pulse width modulation circuit and a feedback circuit. The pulse width modulation circuit provides output voltages in the form of pulses and changes the value and frequency of the output voltages by changing the width, frequency and distribution of the pulses. The feedback circuit includes a resistor string formed by a plurality of resistors. One end of the resistor string is coupled to a variable voltage source. An input end of the pulse width modulation circuit is coupled to two adjacent resistors of the resistor string. The voltage converter adjusts the output voltages by adjusting the variable voltage sources.