VARIABLE CAPACITY ELEMENT AND OSCILLATION CIRCUIT USING THE SAME

摘要

There is provided an oscillation circuit capable of obtaining a wide variable range of oscillation frequency without increasing the current consumption or deteriorating the phase noise. The oscillation circuit includes an amplification circuit (1) and a feedback circuit (2) connected between the output terminal and the input terminal of the amplification circuit (1) and having frequency selectivity. The feedback circuit (2) has a resonance element (XTAL) and MOS capacitor (MC131) whose capacitance value can be varied. The MOS capacitor (MC131) has a gate to which control voltage (Vc) is applied. Furthermore, the drain or the source or both of the MOS capacitor is connected to the input terminal of the amplification circuit (1).