Patent ID: 7495503

Claim:
A current biasing circuit, comprising: a first circuit drawing a first current from a first voltage source, wherein the first circuit comprises a plurality of transistors coupled in series; a second circuit drawing a second current from the first voltage source, wherein the second circuit comprises a plurality of transistors coupled in series, the gate terminal of each transistor of the first circuit is coupled to the gate terminal of one of the transistors of the second circuit, the first current is substantially equal to the second current; a third circuit, coupled between the first circuit and a second voltage source, receiving the first current from the first circuit, comprising a first resistor and a constant-voltage circuit coupled in series, wherein the first resistor has a positive temperature coefficient, the voltage across the constant-voltage circuit is substantially a predetermined constant value; and a second resistor, coupled between the second circuit and the second voltage source, receiving the second current from the second circuit, wherein the second resistor has a negative temperature coefficient.