Abstract: A power amplification circuit includes first and second clock signal generating portions operable to produce, respectively, first and second clock signals different in frequency from each other; first and second PWM signal generating portions operable to produce first and second PWM signals based on first and second input signals using the first and second clock signals, respectively; a first switching amplifier operable to perform a switching operation in response to the first PWM signal to subject the first PWM signal to power amplification to produce a first output signal and to supply the first output signal to a first circuit load; and a second switching amplifier operable to perform a switching operation in response to the second PWM signal to subject the second PWM signal to power amplification to produce a second output signal and to supply the second output signal to a second circuit load.

Abstract: A power amplifier apparatus includes a pair of power amplifiers for performing switching-type power amplification, a transformer, and a capacitor. The transformer is formed of a pair of coils that are connected in series between the corresponding output terminals of the pair of power amplifiers and the corresponding terminals of a speaker. The capacitor is connected in parallel with the output terminals of the pair of coils. With this configuration, a mutual inductance and a leakage inductance are generated in the coils. As a result, 180° out-of-phase and in-phase noise components contained in an output of the power amplifier apparatus can be eliminated.

Abstract: Audio equipment and a method of controlling audio equipment are provided. The equipment comprises a switching power amplifier circuit and a controller controlling a switching frequency of the power amplifier circuit, and the controller varies the switching frequency of the power amplifier circuit in accordance with a receiving frequency in a case of receiving at least a medium-wave broadcast wave.

Abstract: A power amplifier apparatus includes a pair of power amplifiers for performing switching-type power amplification, a transformer, and a capacitor. The transformer is formed of a pair of coils which are connected in series between the corresponding output terminals of the pair of power amplifiers and the corresponding ends of a speaker. The capacitor is connected in parallel with the output terminals of the pair of coils. With this configuration, a mutual inductance and a leakage inductance are generated in the coils. As a result, 180°-out-of-phase and in-phase noise components contained in an output of the power amplifier apparatus can be eliminated.