CAPACITANCE DETECTION CIRCUIT INCLUDING VOLTAGE COMPENSATION FUNCTION
First Claim
1. A capacitance detection circuit for detecting a capacitance change value of a sensor element, the capacitance detection circuit comprising:
- a C-V circuit, connected to the sensor element, for amplifying the capacitance change value of the sensor element by a predetermined gain based on a reference voltage to generate a detection signal; and
a voltage compensation circuit, connected to the C-V circuit, for supplying the reference voltage to the C-V circuit, wherein when the reference voltage fluctuates by a predetermined deviation amount, the voltage compensation circuit reduces the gain relative to the deviation amount.
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Abstract
A capacitance detection circuit that compensates for the fluctuation of a reference voltage with a simple structure. A C-V circuit for a sensor element generates a detection signal by amplifying a capacitance change value of the sensor element by a predetermined gain based on a reference voltage. A voltage compensation circuit, which is connected to the C-V circuit and supplies a reference voltage to the C-V circuit, reduces the gain relative to a deviation amount when the reference voltage fluctuates by a predetermined deviation amount.
13 Citations
20 Claims
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1. A capacitance detection circuit for detecting a capacitance change value of a sensor element, the capacitance detection circuit comprising:
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a C-V circuit, connected to the sensor element, for amplifying the capacitance change value of the sensor element by a predetermined gain based on a reference voltage to generate a detection signal; and a voltage compensation circuit, connected to the C-V circuit, for supplying the reference voltage to the C-V circuit, wherein when the reference voltage fluctuates by a predetermined deviation amount, the voltage compensation circuit reduces the gain relative to the deviation amount. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A capacitance detection circuit for detecting a capacitance change value of a sensor element, the capacitance detection circuit comprising:
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a C-V circuit, connected to the sensor element, for amplifying the capacitance change value of the sensor element by a predetermined gain based on a reference voltage to generate a detection signal; a voltage compensation circuit, connected to the C-V circuit, for supplying the reference voltage to the C-V circuit, wherein when the reference voltage is fluctuated by a certain deviation amount, the voltage compensation circuit reduces the gain relative to the deviation amount; and a voltage divider, connected to the voltage compensation circuit, for dividing the reference voltage by a predetermined ratio and supplying the divided reference voltage to the voltage compensation circuit. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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Specification