| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve the problem that, in an electrostatic capacitance detection circuit, a capacitance corresponding to a fixed capacitance can be canceled by providing a correction capacitance but when the fixed capacitance is large, it is necessary to provide a correction capacitance corresponding thereto, and for an IC a configuration circuit area may be expanded or any external capacitance may be required. <P>SOLUTION: An electrostatic capacitance detection circuit includes: a conversion section for converting a capacitance value of a capacitance to be detected, having a fixed capacitance and a variable capacitance which is variable in response to a change of a target to be measured, into a voltage; a DA converter for outputting an analog voltage corresponding to an inputted digital signal; and cancel means for subtracting the output voltage of the DA converter connectable to the conversion section from the voltage converted by the conversion section corresponding to the capacitance to be detected. The output voltage of the DA converter is less than or equal to an offset voltage converted by the conversion section corresponding to the fixed capacitance. <P>COPYRIGHT: (C)2012,JPO&INPIT |
