Patent ID: 6396357
Filing Date: 2002-05-28
Classification: H03K

Abstract:
A ring oscillator comprising:a voltage-to-current converter for producing at least one control current from at least one control voltage; and, a plurality of delay cells coupled to the converter, wherein at least one output of the one of the delay cells is coupled to the input of another of the delay cells, wherein the voltage-to-current converter produces a substantially linear output when the at least one control voltage is varied between zero volts and a rail supply voltage, wherein the voltage-to-current converter includes at least two stages, a first stage for producing a first component of the control current, and a second stage for producing a second component of the control current, wherein the first stage of the voltage-to-current converter comprises: a first transistor having a gate terminal coupled to the at least one control voltage; a second transistor having a gate terminal coupled to a source of the first transistor; a third transistor having a gate terminal and a drain terminal coupled to a drain of the second transistor; and, a fourth transistor having a gate terminal coupled to the drain of the second transistor.