Electronic device and control method

An electronic device comprising:

• a core circuit, having a central processor unit and a codec;
• a microphone;
• a bias-supply device, configured to provide a first bias voltage to serve as an operation voltage of the microphone when the electronic device is operated in a power-saving mode, such that the microphone transforms a voice signal into a first output signal;
• and
• a voice-recognition device, configured to receive the first output signal and output a control signal, when the first output signal has a predetermined signal, to enable the electronic device be operated in a normal operation mode and the bias-supply device to provide a second bias voltage that is higher than the first bias voltage to serve as the operation voltage of the microphone, such that the microphone transforms the voice signal into a second output signal and outputs the second signal to the codec, wherein a waveform of the predetermined signal is a truncated sine wave, wherein the microphone non-linearly transforms the voice signal into the first output signal when the operation voltage of the microphone is the first bias voltage, and the microphone linearly transforms the voice signal into the second output signal when the operation voltage of the microphone is the second bias voltage;
• wherein the bias-supply device comprises:
• a first resistor, having a first terminal coupled to a power voltage and a second terminal coupled to the voice-recognition device;
• a second resistor, having a first terminal coupled to the power voltage and a second terminal coupled to the codec;
• and
• a switching device, configured to selectively couple one of the first resistor and the second resistor to a power input terminal of the microphone.

A control method, comprising:

• providing a first bias voltage to serve as an operation voltage of a microphone and to non-linearly transform a voice signal into a first output signal by the microphone, when an electronic device is operated in a power-saving mode;
• switching the operation of the electronic device from the power-saving mode to a normal operation mode, when the first output signal has a predetermined signal;
• providing a second bias voltage that is higher than the first bias voltage to serve as the operation voltage of the microphone and to linearly transform the voice signal to a second output signal by the microphone, when the electronic device is operated in the normal operation mode;
• and
• outputting the second output signal to a core circuit of the electronic device.