| 摘要 |
PURPOSE:To improve the linearity by feeding back a current for a low frequency band of an input signal and feeding back a current for a high frequency band in an acoustic power amplifier which drives a speaker. CONSTITUTION:When an input signal (ei) is a low frequency signal in the cut-off region of an HPF10, the part between points (a) and (c) has a high impedance by the HPF10. Therefore, a speaker 4 is driven with a constant voltage by an amplifier consisting of an amplifier 1 and resistances 7 and 8. When the input signal (ei) is a signal in the passing band of the HPF10, the part between points (a) and (c) is made conductive. In this case, the value of the resistance 8 is made sufficiently higher than the voice coil impedance of the speaker 4, and the value of the resistance 7 is made sufficiently higher than that of a resistance 9. Therefore, feedback determined by the speaker 4 and the resistance 9 is applied to the amplifier 1, and the speaker 4 is driven with a constant current. Thus, the linearity is improved. |
