PURPOSE: A voltage controlled oscillator is provided to reduce current consumption by adaptively controlling an amount of bias currents according to a frequency of an output clock signal. CONSTITUTION: An oscillator outputs first and second output clock signals with a frequency which is varied in response to a control voltage. An active device(200) is connected to the oscillator and maintains the oscillation of the oscillator. A bias current generator(500) is connected to the active device at a bias node and adaptively controls an amount of bias currents provided to the bias node in response to the control code. First and second capacitor banks(300,400) are connected to the oscillator and the active device at a first output node and a second output node and provides first and second load capacitance to the first output node and the second output node in response to the control code.
