摘要 |
PROBLEM TO BE SOLVED: To provide a speaker driving circuit with a simple configuration without needing any DC current cutting capacitor. SOLUTION: Class D amplifiers 121L, 121R of a headphone drive circuit 12 amplify a left channel signal L+ and a right channel signal R+ of a stereo signal into signals AL+ and AR+ with a bias voltage VDD/2 as an amplitude center. The signals AL+ and AR+ are supplied to one-side ends of speaker coils 21L, 21R of a headphone 20 respectively. A VDD/2 generating circuit 122 of the headphone drive circuit 12 comprises a class D amplifier, generates a voltage VDD/2 equal to the bias voltage and applies the voltage to the other-side ends of the speaker coils 21L, 21R, respectively. Thus, potential differences of DC components included in the amplified left channel signal AL+ and right channel signal AR+ are not generated to the speaker coils 21L, 21R of the headphone 20. COPYRIGHT: (C)2008,JPO&INPIT |