| 摘要 |
PROBLEM TO BE SOLVED: To provide a capacitance sensing circuit which has low noise characteristics and is capable of accurately sensing capacitance with a high S/N ratio without increasing circuit scale and power consumption.SOLUTION: A capacitance sensing circuit 101 of the present invention is used for capacitance touch sensors. A continuous-time CV conversion circuit 110 converts capacitance variation of a capacitance touch sensor of a touch panel 50 into a voltage signal. A synchronous demodulation circuit 120 demodulates an output signal of the continuous-time CV conversion circuit 110 using synchronous demodulation signals. A low-pass filter circuit 130 limits a band of an output signal of the synchronous demodulation circuit 120. A controller section 140 generates the synchronous demodulation signals. |
