Patent ID: 8155353

Claim:
A device for driving a speaker, comprising: a distortion detector configured to detect distortion caused in the voltage of an audio signal at the input to the speaker due to a back electromotive force generated by loads in the speaker and output; and a subtraction amplifier, an input of which is electrically coupled to an output of the distortion detector, configured to eliminate a distorted voltage detected by the distortion detector, from the voltage of the audio signal, wherein a signal output from the subtraction amplifier is amplified by a first amplification circuit and supplied to the speaker, wherein the distortion detector includes: a second amplification circuit having a same voltage gain as the first amplification circuit and operable to amplify the input audio signal; and a comparison circuit for comparing the voltage of the audio signal received from the first amplification circuit with an output voltage of the second amplification circuit to be used as a reference.