Patent ID: 8884603

Claim:
A reference power supply circuit comprising: an adjustable resistance network comprising a first resistor end and a second resistor end, the resistance between the first resistor end and the second resistor end varies with a process deviation; and a bandgap reference power supply circuit connecting the first resistor end with the second resistor end, for generating a positive proportional to absolute temperature current flowing through the first resistor end and the second resistor end, and for outputting a reference voltage related to the positive proportional to absolute temperature current, wherein the adjustable resistance network comprises a plurality of sets of selection units having identical structures between the first resistor end and the second resistor end for selecting different resistance according to an input control signal, the plurality of sets of selection units further including: a first set of selection unit having a first switch NMOS transistor, a second switch NMOS transistor and a first resistor, a second set of selection unit having a third switch NMOS transistor, a fourth switch NMOS transistor and a second resistor, and a third set of selection unit having a fifth switch NMOS transistor, a sixth switch NMOS transistor and a third resistor.