In accordance with an embodiment, a method of operating a voltage controlled oscillator (VCO) includes generating a first oscillating signal in a first VCO core and generating a second oscillating signal in a second VCO core, such that the first oscillating signal and the second oscillating signal have a same frequency and a fixed phase offset. The VCO includes the first VCO core and the second VCO core, and each VCO core includes a pair of transistors. The VCO also includes a transformer having a first winding coupled between control nodes of the pair of transistors of the first VCO core and a second winding coupled between control nodes of the pair of transistors of the second VCO core.