Patent attributes
An object is to improve the signal-to-noise ratio (SNR). A signal processing circuit includes first to fourth terminals, a switch circuit, and an integrator circuit. The integrator circuit includes an amplifier circuit. The amplifier circuit has an output terminal, a terminal (−), a first terminal (+), and a second terminal (+). The switch circuit has a function of electrically connecting the terminal (−) to the second terminal, the first terminal (+) to the first terminal, and the second terminal (+) to the third terminal; and a function of electrically connecting the terminal (−) to the third terminal, the first terminal (+) to the second terminal, and the second terminal (+) to the fourth terminal. The integrator circuit integrates a signal input to the terminal (−), with an average voltage of the voltages of the first terminal (+) and the second terminal (+) as a reference voltage. The integrator circuit removes common mode noise from the signal input to the terminal (−) and thus can output a signal with high SNR. The signal processing circuit is used for a sensing circuit of a touch sensor, for example.
