| 摘要 |
A synchronous detection circuit includes: an offset compensation circuit which generates an offset compensation voltage to compensate an offset voltage superposed on a direct current voltage signal; and a temperature compensation circuit which generates a temperature compensation voltage to compensate variation of a direct current reference voltage that depends on a temperature in a signal path of a sensing circuit. In the circuit, the synchronous detection circuit synchronously detects an alternating current signal, the offset compensation voltage and the temperature compensation voltage are respectively superposed on the alternating current signal which is input into the synchronous detection circuit, and the synchronous detection circuit synchronously detects the alternating current signal on which the offset compensation voltage and the temperature compensation voltage have been superposed. |
