| 摘要 |
PROBLEM TO BE SOLVED: To provide a technology of capable of detecting disconnections or the like of speakers immediately at timing that disconnections or the like in all the speakers occur without necessity of attaching signal generation means for inspection used to detect such disconnections.SOLUTION: A power amplifier 1 includes a class D amplifier part 100 that performs self-oscillation at a predetermined self-oscillation frequency through a feedback loop including a speaker SP, generates a pulse duration modulation signal subjected to pulse duration modulation according to an audio signal AIN and supplies the pulse duration modulation signal to the speaker SP. A disconnection detection circuit 300 determines the presence/absence of a disconnection in the speaker SP according to whether or not the self-oscillation frequency of the class D amplifier part 100 changes from a predetermined reference frequency.SELECTED DRAWING: Figure 1 |
