Patent ID: 6831504
Filing Date: 2004-12-14
Classification: G05F

Abstract:
A current source, comprising:a voltage source providing a first supply voltage; a first current source coupled to the first supply voltage and providing a first current to a first node; a first circuit branch comprising a first transistor being diode-connected, a resistor and a second transistor being diode-connected, all connected in series between the first node and a ground node, the first transistor being diode-connected through the resistor; a second circuit branch comprising an inverter including a third transistor and a fourth transistor connected in series between the first node and the ground node, the inverter receiving a first voltage as an input voltage and generating an output voltage; and a third circuit branch comprising a shunt regulator coupled between the first node and the ground node and controlled by the output voltage of the second circuit branch, the shunt regulator being operated to regulate a voltage at the first node in response to the output voltage, wherein the first, second, third and fourth transistors are biased in the subthreshold region, and the transistors in each of the first and second circuit branches have non-nominal transistor size ratios such that the first voltage is established at a first terminal of the resistor and a second voltage is established at a second terminal of the resistor and a voltage across the resistor is a voltage proportional to absolute temperature.