MOS-type capacitor and integrated circuit VCO using same
AssigneeInterchip Corporation
InventorsMasaaki Kamiya, Yutaka Saitoh
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Abstract
A MOS-type capacitor includes a semiconductor substrate of a first conductive type serving as a first electrode, a conductor layer formed on the semiconductor substrate via a capacitive insulation film and serving as a second electrode, and an impurity region of a second conductive type formed in the vicinity of the surface of the semiconductor substrate at a location in proximity to a region facing the conductor layer. The MOS-type capacitor is used as a variable capacitor in a VCO (voltage-controlled oscillator) having a widened frequency range.
Claims9
A MOS-type capacitor comprising:
- a semiconductor substrate of a first conductive type serving as a first electrode;
- a conductor layer formed on the semiconductor substrate via a capacitive insulation film and serving as a second electrode;
- and
- an impurity region of a second conductive type formed in the vicinity of the surface of the semiconductor substrate at a location in proximity to a region facing the conductor layer, wherein a DC voltage is applied to the second-conductive-type impurity region, the DC voltage serving as a reverse voltage against a diode formed by the semiconductor substrate and the second-conductive-type impurity region;
- and through application of a control voltage applied to the conductor layer, the capacitance of a capacitor element formed between the first and second electrodes is changed.
A semiconductor integrated circuit device comprising a voltage-controlled oscillation circuit which in turn comprises, as constituent elements, an oscillation amplifier and a variable capacitor whose capacitance can be changed in accordance with a control voltage, wherein the variable capacitor is formed of a MOS-type capacitor comprising:
- a semiconductor substrate of a first conductive type serving as a first electrode;
- a conductor layer formed on the semiconductor substrate via a capacitive insulation film and serving as a second electrode;
- and
- an impurity region of a second conductive type formed in the vicinity of the surface of the semiconductor substrate at a location in proximity to the conductor layer, wherein a DC voltage is applied to the second-conductive-type impurity region, the DC voltage serving as a reverse voltage against a diode formed by the semiconductor substrate and the second-conductive-type impurity region;
- and through application of a control voltage applied to the conductor layer, the capacitance of a capacitor element formed between the first and second electrodes is changed.
Dependencies are inferred from the claim text.