A voltage controlled oscillator comprising: a ring of inverters comprised of an odd number of serially connected CMOS inverter stages, the inverter stages being connected between first and second oppositely poled power leads, a MOSFET having a source-drain circuit connected between one of the power leads and a first power rail, the other power lead being connected to a second power rail, apparatus for operating the MOSFET in saturation, and apparatus for applying a control voltage to the gate of the MOSFET, referenced to the second power lead, whereby the MOSFET operates as a nonlinear current conduction device having a characteristic such as to linearize the voltage-frequency characteristic of the combined MOSFET--ring oscillator combination.