Patent ID: 7508263

Claim:
A digital amplifying apparatus having amplifiers and low-pass filters, the amplifiers operating in a switching scheme and being respective to a positive signal and a negative signal in opposite phase of each other, the switching scheme causing switching noise respectively in the positive signal and the negative signal, the low-pass filters being respective to the positive signal and the negative signal, and the positive signal and the negative signal from the low-pass filters being transmitted to a speaker through a balanced transformerless connection, the digital amplifying apparatus comprising: noise component extracting units that respectively extract a first residual component from the positive signal, the first residual component being the switching noise that is not removed by the low-pass filter respective to the positive signal, and a second residual component from the negative signal, the second residual component being the switching noise that is not removed by the low-pass filter respective to the negative signal; noise component coupling units that respectively couple the first residual component extracted by the noise component extracting unit with the second residual component present in the negative signal, and the second residual component extracted by the noise component extracting unit with the first residual component present in the positive signal; and a same-phase component removing unit that receives the positive signal and the negative signal respectively output from the noise component coupling units, and respectively from the positive signal and the negative signal, removes the switching noise that is in phase.