| 摘要 |
PURPOSE:To provide an inexpensive voice signal amplifier circuit capable of taking out large output signals by enlarging the power supply voltage of an amplifier only on one side concerning the voice signal amplifier circuit used in an exchange and a subscriber's terminal equipment. CONSTITUTION:The input of an arithmetic circuit 50 for impressing DC bias is connected to the analog output terminal OA of a codec 30, the output of the arithmetic circuit 50 is connected to the input of a reception amplifier 40 whose power source is the voltage of an absolute value different in sign and the output of the reception amplifier 40 is connected to one of the terminals of a hybrid coil HYB through a terminating resistor R3. The middle point of the hybrid coil HYB is connected to earth potential through a resistor R2 and the other terminal of the hybrid coil HYB is connected to the earth potential through the terminating resistor R1 and connected to the input of a DC cut filter 10 at the same time. The output is connected to the analog input terminal IA of the codec 30 through a transmission amplifier 20 whose power source is the voltage of the absolute value different in the sign. |
