| 摘要 |
PURPOSE:To prevent a distrubance of output due to a disturbance of impedance, by producing a product signal with the output current and the output voltage of an audio power amplifier and controlling the output voltage so that the product signal output follows an input signal. CONSTITUTION:The voltage signal Vi produced across a minor resistance Ri is properly amplified and then multiplied by a coefficient to be led to the arithmetic input at one side of a multiplying circuit M. On the other hand, the voltage signal is multiplied by the coefficient which is obtained by voltage-dividing properly to the output voltage Vo emerging at an output terminal of an amplifier A, and then led to the other arithmetic input of the circuit M. The arithmetic output Vf of the circuit M is applied to the reverse input (-) of the amplifier A. As a result, the voltage Vo receives a negative feedback control so that the output Vf follows an input signal Vs. |
