Patent ID: 7906952

Claim:
A voltage regulator comprising: a comparator having a first input end, a second input end, and an output end, the first input end used to receive a reference voltage; a first voltage output unit comprising: a first P-type transistor having a source coupled to an operating voltage, a drain coupled to a first resistor, and a gate coupled to the output end of the comparator; and a second resistor coupled between the other end of the first resistor and a ground, wherein a common node of the first resistor and the second resistor is coupled to the second input end of the comparator; a second voltage output unit comprising: a second P-type transistor having a source coupled to the operating voltage and a drain coupled to a capacitor, the other end of the capacitor coupled to the ground; and a current buffer coupled between the drain of the first P-type transistor and the drain of the second P-type transistor, an output end of the current buffer coupled to a gate of the second P-type transistor and adjusting the gate voltage of the second P-type transistor according to the drain voltage of the first P-type transistor and the drain voltage of the second P-type transistor; a first switch coupled between the gate of the first P-type transistor and the gate of the second P-type transistor; and a second switch coupled between the drain of the first P-type transistor and the drain of the second P-type transistor.