In one embodiment, a voltage controlled oscillator (VCO) is provided. The VCO includes a tank circuit. Also, the VCO includes a first pair of transistors. The drains of the first pair of transistors are coupled to the tank circuit and the gates of the first pair of transistors are cross-coupled with the drains of the first pair of transistors. The first pair of transistors each have a first threshold voltage. The VCO further includes a second pair of transistors. The drains of the second pair of transistors are respectively coupled to the sources of the first pair of transistors and the gates of the second pair of transistors are respectively coupled to the gates of the first pair of transistors, The second pair of transistors each have a second threshold voltage higher than the first threshold voltage.