Signal processing device and detection method

Abstract

A signal processing device coupled to an audio jack and includes a detection controller and an analog to digital converter. The detection controller controls a bias circuit to provide a bias voltage to the audio jack in response to a trigger signal indicating that a device has been plugged into the audio jack. The analog to digital converter is coupled to a detection point of the audio jack and performs analog to digital conversion on a voltage of the detection point to generate an output voltage. The detection controller detects a voltage difference of the output voltage caught from the analog to digital converter at different time and determines whether the voltage difference is smaller than a threshold. In response to a result of determining that the voltage difference is smaller than the threshold, the detection controller determines that the device is a headphone without a microphone.

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