Multiplexing circuit and mobile terminal

A multiplexing circuit, comprising:

• a first switch circuit, a second switch circuit, and a third switch circuit, a first signal transmission end, a second signal transmission end, a right sound channel transmission end, a left sound channel transmission end, a first output end, and a second output end;
• the first switch circuit is coupled to the first signal transmission end and the right sound channel transmission end, and the first switch circuit is configured to:
• receive a first voltage, and transmit, to the first signal transmission end under control of the first voltage, a right sound channel audio signal provided by the right sound channel transmission end;
• the second switch circuit is coupled to the second signal transmission end and the left sound channel transmission end, and the second switch circuit is configured to:
• receive the first voltage, and transmit, to the second signal transmission end under control of the first voltage, a left sound channel audio signal provided by the left sound channel transmission end;
• and
• the third switch circuit is coupled to the first signal transmission end, the second signal transmission end, the first output end, and the second output end, and the third switch circuit is configured to:
• receive a second voltage, transmit, to the first output end under control of the second voltage, a signal provided by the first signal transmission end, and transmit, to the second output end, a signal provided by the second signal transmission end;
• or the third switch circuit is configured to:
• receive the second voltage, transmit, to the first signal transmission end under control of the second voltage, a signal provided by the first output end, and transmit, to the second signal transmission end, a signal provided by the second output end;
• wherein
• the first switch circuit comprises a first transistor and a first constant voltage control circuit, wherein
• a gate electrode of the first transistor is configured to receive the first voltage, a first electrode is coupled to the first signal transmission end, and a second electrode is coupled to the right sound channel transmission end;
• and
• the first constant voltage control circuit is coupled to the gate electrode and the second electrode of the first transistor, and the first constant voltage control circuit is configured to load the right sound channel audio signal to the gate electrode of the first transistor;
• and
• the second switch circuit comprises a second transistor and a second constant voltage control circuit, wherein
• a gate electrode of the second transistor is configured to receive the first voltage, a first electrode is coupled to the second signal transmission end, and a second electrode is coupled to the left sound channel transmission end;
• and
• the second constant voltage control circuit is coupled to the gate electrode and the second electrode of the second transistor, and the second constant voltage control circuit is configured to load the left sound channel audio signal to the gate electrode of the second transistor.

A mobile terminal, comprising a central processing unit, an audio codec, an external interface configured to be coupled to an external device, and a multiplexing circuit, wherein the external interface comprises a D+ pin and a D− pin that are specified according to a Type-C interface protocol;

• the multiplexing circuit comprising:
• a first switch circuit, a second switch circuit, and a third switch circuit, wherein the multiplexing circuit further comprises a first signal transmission end, a second signal transmission end, a right sound channel transmission end, a left sound channel transmission end, a first output end, and a second output end;
• the first switch circuit is coupled to the first signal transmission end and the right sound channel transmission end, and the first switch circuit is configured to:
• receive a first voltage, and transmit, to the first signal transmission end under control of the first voltage, a right sound channel audio signal provided by the right sound channel transmission end;
• the second switch circuit is coupled to the second signal transmission end and the left sound channel transmission end, and the second switch circuit is configured to:
• receive the first voltage, and transmit, to the second signal transmission end under control of the first voltage, a left sound channel audio signal provided by the left sound channel transmission end;
• and
• the third switch circuit is coupled to the first signal transmission end, the second signal transmission end, the first output end, and the second output end, and the third switch circuit is configured to:
• receive a second voltage, transmit, to the first output end under control of the second voltage, a signal provided by the first signal transmission end, and transmit, to the second output end, a signal provided by the second signal transmission end;
• or the third switch circuit is configured to:
• receive the second voltage, transmit, to the first signal transmission end under control of the second voltage, a signal provided by the first output end, and transmit, to the second signal transmission end, a signal provided by the second output end;
• wherein
• the first switch circuit comprises a first transistor and a first constant voltage control circuit, wherein
• a gate electrode of the first transistor is configured to receive the first voltage, a first electrode is coupled to the first signal transmission end, and a second electrode is coupled to the right sound channel transmission end;
• and
• the first constant voltage control circuit is coupled to the gate electrode and the second electrode of the first transistor, and the first constant voltage control circuit is configured to load the right sound channel audio signal to the gate electrode of the first transistor;
• and
• the second switch circuit comprises a second transistor and a second constant voltage control circuit, wherein
• a gate electrode of the second transistor is configured to receive the first voltage, a first electrode is coupled to the second signal transmission end, and a second electrode is coupled to the left sound channel transmission end;
• and
• the second constant voltage control circuit is coupled to the gate electrode and the second electrode of the second transistor, and the second constant voltage control circuit is configured to load the left sound channel audio signal to the gate electrode of the second transistor;
• a first signal transmission end of the multiplexing circuit is coupled to the D+ pin, a second signal transmission end is coupled to the D− pin, and a right sound channel transmission end and a left sound channel transmission end are coupled to the audio codec;
• the audio decoder is further coupled to the central processing unit, and the audio codec is configured to:
• decode an audio signal output by the central processing unit, provide a right sound channel audio signal to the right sound channel transmission end, and provide a left sound channel audio signal to the left sound channel transmission end;
• and
• a first output end and a second output end of the multiplexing circuit are coupled to the central processing unit, and the multiplexing circuit is configured to:
• provide a signal of the D+ pin and a signal of the D− pin to the central processing unit through the first output end and the second output end respectively, or provide a signal of the central processing unit for the D+ pin and the D− pin through the first output end and the second output end respectively.