Voltage reference circuit and method for providing reference voltage

A voltage reference circuit, comprising:

• a first diode-connected transistor, wherein a bulk and a source of the first diode-connected transistor are coupled to a ground;
• a second diode-connected transistor, wherein gates and drains of the first and second diode-connected transistors are coupled together;
• and
• an output node coupled to a source and a bulk of the second diode-connected transistor, and configured to output a reference voltage,
• wherein size of the first diode-connected transistor is less than that of the second diode-connected transistor,
• wherein the flipped-gate transistor and the transistor form a diode pair.

A method for providing a reference voltage, comprising:

• obtaining a first current ratio of a first current of a first flipped-gate transistor to a second current of a first non-flipped-gate transistor in a first circuit, wherein the first current ratio corresponds a temperature coefficient of zero, and the first flipped-gate transistor and the first non-flipped-gate transistor are the same size;
• mirroring a bias current to generate a third current across a second flipped-gate transistor and to generate a mirroring current in a second circuit;
• mirroring the mirroring current to generate a fourth current across a second non-flipped-gate transistor in the second circuit;
• and
• outputting the reference voltage in response to the fourth current,
• wherein a second current ratio of the third current to the fourth current is equal to the first current ratio,
• wherein the flipped-gate transistor and the transistor form a diode pair.