A voltage controlled oscillator.

A voltage controlled oscillator for upconverting / downconverting a resonant frequency in a digital radio communication system, comprising: a resonance unit (100), which has a component with variable capacitance in parallel to a series resonant circuit which comprises a series circuit of a capacitance diode (VD2) with an inductive component (L) is made, wherein the series resonant frequency of the series resonant circuit to the level of a over the capacitance diode (VD2) applied mode voltage can be varied, and an oscillator unit (200) for generating a vibration having a frequency (f having the voltage mode during the transmitting operation of the radio communication system a transmission level (V