Patent ID: 7098751

Claim:
An apparatus including a tunable capacitance for a voltage control oscillator (VCO), comprising: at least one control electrode to convey a tuning voltage; at least one tank electrode to couple to inductive circuitry of a VCO; first and second signal reference electrodes to convey first and second DC bias voltages; first tunable capacitance circuitry, including at least one P-N junction varactor with anode and cathode electrodes, coupled to said at least one control electrode, one or more of said at least one tank electrode and said first signal reference electrode; and second tunable capacitance circuitry, including at least one metal oxide semiconductor (MOS) accumulation-mode varactor with gate, drain and source electrodes, coupled to said at least one control electrode, one or more of said at least one tank electrode and said second signal reference electrode; wherein: said anode electrode is coupled to said at least one control electrode; said cathode electrode is coupled to said first signal reference electrode; said gate electrode is coupled to said one or more of said at least one tank electrode; and said drain and source electrodes are coupled to said second signal reference electrode.