| 摘要 |
A control voltage Vin that has been input is sequentially reduced at NMOS's 111~113 constituting means for voltage reduction. The individual voltages resulting from the voltage reduction are applied to control electrodes of MOS varactors 211~213 constituting voltage-controlled variable-capacitance elements which are connected in parallel and, thus, the capacitance values of the individual MOS varactors 211~213 are determined. An LC resonance circuit constituted of the MOS varactors 211~213 and a coil 22 resonates at a specific frequency, NMOS's 23 and 24 constituting means for switching engage in on/off operation and oscillation occurs at an oscillation frequency corresponding to the voltage Vin resulting in an oscillation signal output through output terminals 3 and 4. Thus, an LC resonance circuit that allows the rate at which the capacitance values of the voltage-controlled variable-capacitance elements change to be set freely in correspondence to the particulars of design and a high-performance voltage-controlled oscillation circuit (VCO) that employs this LC resonance circuit and enables good control are provided. |
