| 摘要 |
PURPOSE:To obtain an amplifying circuit high in efficiency and excellent in distortion characteristics, by separating an amplifying signal into low and high frequency component and amplifying the low frequency at a PWM amplifying circuit and the high frequency component at a conventional analog amplifying circuit respectively. CONSTITUTION:A signal inputted to an input terminal 10 is split at a low-pass filter 11 and a high-pass filter 12. An amplifying circuit 13 of PWM system is connected in cascade to the low-pass filter 11 and a conventional analog amplifying circuit 14 of class A or B is connected to the high-pass filter 12 and the signals are amplified. In this case, the split frequency of a filter splitting the band is at about 1kHz and the synthesized characteristics of the filter and the amplifying circuit are of flat frequency characteristics at the entire band. Since the low frequency component concentrated with energy among the amplification signal is amplified with highly efficient PWM system, the efficiency can be increased. |
