Abstract: A voltage-controlled oscillator for generating differential output is disclosed. The voltage-controlled oscillator comprises a Colpitts oscillator having a first inductor and a capacitive divider having at least two capacitors connected in series. A varactor is connected in series with the capacitive divider and to a reference voltage, and a second inductor is mutually coupled to the first inductor for providing the differential output. A second inductor is substantially centrally tapped and connected to the reference voltage for providing a substantially balanced output. The operating frequency of the voltage-controlled oscillator is dependent on an applicable potential difference across the varactor.