| 摘要 |
PROBLEM TO BE SOLVED: To provide an MOS type variable capacitance element having a variable range broader than a conventional one, and an integrated circuit which mounts thereon an oscillation circuit employing the element, without raising costs. SOLUTION: The MOS type variable capacitance element consists of; a planar capacitive region which is formed on the surface of a first conductive type semiconductor substrate and extended in a first direction; and a capacitive electrode which is formed opposite to the capacitive region with a capacitive insulating film being interposed therebetween to form an MOS capacitance. An impurity diffusion region of a second conductive type which is different from the first conductive type is provided along at least one of the two sides extended to the first direction of the capacitive region. Thus, a significant improvement is achieved in the variance width of a capacitance value with respect to the variation of control signal voltage impressed on the capacitive electrode. Accordingly, a frequency variable oscillator which is constituted by using the MOS type variable capacitance element enables changing of an oscillation frequency over a wide range. COPYRIGHT: (C)2004,JPO
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