Driving circuit of loudspeaker and method for generating current sampling signal of loudspeaker

A method for generating a current sampling signal of a loudspeaker, comprising:

• generating a periodic signal and a control signal, wherein the control signal is arranged to indicate occurrence timing of a specific extreme value of the periodic signal;
• generating a pre-driving signal according to a first audio input signal, a second audio input signal, and the periodic signal, wherein the second audio input signal is an inverse of the first audio input signal;
• driving the loudspeaker, by a class-D amplifier circuit, according to the pre-driving signal;
• sensing a driving current of the loudspeaker, by a current sensing circuit, to generate a current sensing signal;
• and
• according to the control signal, sampling and holding the current sensing signal only when the periodic signal has the specific extreme value, to generate the current sampling signal;
• wherein at the occurrence timing of the specific extreme value of the periodic signal, a current simultaneously flows through the loudspeaker and multiple resistors comprised in the current sensing circuit.

A driving circuit of a loudspeaker, comprising:

• a periodic signal generation circuit, arranged to generate a periodic signal;
• a signal processing circuit, coupled to the periodic signal generation circuit, and arranged to receive a first audio input signal, a second audio input signal, and the periodic signal, and generate a pre-driving signal according to the first audio input signal, the second audio input signal, and the periodic signal, wherein the second audio input signal is an inverse of the first audio input signal;
• a class-D amplifier circuit, coupled to the signal processing circuit, and arranged to drive the loudspeaker according to the pre-driving signal;
• a current sensing circuit, coupled to the class-D amplifier circuit, and arranged to sense a driving current of the loudspeaker to generate a current sensing signal, wherein the current sensing circuit comprises multiple resistors;
• a logic control circuit, coupled to the signal processing circuit, and arranged to generate a control signal according to the pre-driving signal;
• and
• a sample and hold circuit, coupled to the current sensing circuit and the logic control circuit, wherein according to the control signal, the sample and hold circuit samples and holds the current sensing signal only when a current simultaneously flows through the loudspeaker and the multiple resistors, to generate a first current sampling signal.

A method for generating a first current sampling signal of a loudspeaker, comprising:

• generating a periodic signal;
• generating a pre-driving signal according to a first audio input signal, a second audio input signal, and the periodic signal, wherein the second audio input signal is an inverse of the first audio input signal;
• driving the loudspeaker, by a class-D amplifier circuit, according to the pre-driving signal;
• sensing a driving current of the loudspeaker, by a current sensing circuit, to generate a current sensing signal;
• generating a control signal according to the pre-driving signal;
• and
• according to the control signal, sampling and holding the current sensing signal only when a current simultaneously flows through the loudspeaker and multiple resistors comprised in the current sensing circuit, to generate a second current sampling signal.