Patent ID: 7075360
Filing Date: 2006-07-11
Classification: G05F

Abstract:
1. 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 MOS transistor of a first conductivity type and having a source terminal coupled to the first node, a drain terminal coupled to a current mirror, and a gate terminal coupled to receive a first DC reference voltage; a resistor having a first terminal coupled to the first node and a second terminal, the resistor having negative temperature coefficient; a second MOS transistor of the first conductivity type and having a source terminal coupled to the second terminal of the resistor, a drain terminal coupled to the current mirror, and a gate terminal coupled to receive a second DC reference voltage, the difference between the first and the second DC reference voltages being a voltage proportional to absolute temperature; and a shunt regulator coupled between the first node and a ground node and controlled by a control voltage being a voltage at the drain terminal of the first MOS transistor, the shunt regulator being operated to regulate a voltage at the first node in response to the control voltage, wherein the first and second MOS transistors are of unequal area and are biased in the subthreshold region, and wherein the voltage proportional to absolute temperature is combined with a voltage difference of the gate-to-source voltages of the first and second MOS transistors, the combined voltage being imposed on the resistor to generate a current flowing in the resistor and the second MOS transistor being super proportional to absolute temperature.