Patent ID: 8600081

Claim:
An audio signal amplifying circuit for an electronic device comprising a processing chip and a speaker, the audio signal amplifying circuit comprising: a control signal generating circuit comprising: a first port connected to a pin of the processing chip to receive a first control signal from the processing chip; a second port; and an inverting circuit connected between the first port and the second port to invert the first control signal from the first port to generate a second control signal; and an amplifying circuit comprising a first resistor, a second resistor, a third resistor, a fourth resistor, a signal input port, a signal output port, and a first switch, wherein the amplifying circuit switches an operation mode thereof according to the first control signal and/or the second control signal, the first resistor and the second resistor are connected in series between the first port and the second port, a base of the first switch is connected to the first resistor and the second resistor respectively, a first node is formed among the first resistor, the second resistor, and the base of the first switch, the signal input port is connected to the first node to input audio signals generated by playing audio/video files of the electronic device to the amplifying circuit, a collector of the first switch is connected to the second port through the third resistor, an emitter of the first switch is connected to the first port through the fourth resistor, a second node is formed among the third resistor, the collector of the first switch, and the speaker, and the second node is used as a signal output port of the amplifying circuit; wherein the operation modes of the amplifying circuit comprise an amplifying mode and a non-amplifying mode; wherein, when the first control signal from the first port is a high positive voltage, the amplifying circuit is in the non-amplifying mode, and audio signals from the signal output port is substantially the same as audio signals from the signal input port; and wherein, when the first control signal from the first port is a high negative voltage, the amplifying circuit is in the amplifying mode, and audio signals from the signal input port are amplified and transmitted to the speaker through the signal output port.