Patent ID: 7388447

Claim:
A circuit for providing a stabilized bias current to a ring oscillator, comprising: a biasing transistor configured to provide the stabilized bias current, wherein the biasing transistor is provided a gate source voltage VGS such that VGS=Vth+ΔVbe, and a drain source voltage VDS that is proportional to a threshold voltage Vth such that VDS=α*Vth, α being a constant; a cascode circuit comprising a gate-coupled transistor pair, wherein one transistor is coupled to a drain of the biasing transistor and is configured to provide VDS; a serially coupled second resistor and a diode connected first transistor configured to provide VGS, wherein the diode connected first transistor is arranged to provide Vth and a voltage across the second resistor is proportional to ΔVbe, and wherein ΔVbe is proportional to a ratio of emitter areas of two junction transistors a pair of base-coupled junction transistors; and a first resistor coupled to an emitter of one of the base-coupled junction transistor pair, wherein the base-coupled junction transistor pair is configured to provide a base emitter voltage to the second resistor such that the voltage across the second resistor is ΔVbe times a ratio of a resistance of the second transistor to a resistance of the first transistor, and wherein ΔVbe is proportional to a natural logarithm of the ratio of emitter areas of the base-coupled pair of junction transistors.