| 摘要 |
<p>PURPOSE:To remove a capacitor with high breakdown strength and large capacity by generating DC impedance and AC end impedance from the 1st feedback loop having a constant feedback coefficient with respect to DC and AC and a group of said 1st loop and the 2nd feedback loop having a feedback impedance becoming a negative one with respect to AC, respectively. CONSTITUTION:A difference voltage between a supply voltage VBB and a subscriber interterminal voltage detected by a voltage/current conversion circuit 7 is converted into two output currents (VBB-Vin)g1 where a conversion coefficient of the circuit 7 is g1. One output current is transmitted to a circuit 6 through the 1st feedback loop as it is. The other output current Ving1 of the output current of the circuit 7 is inputted to a current/voltage conversion circuit 18. An output voltage of the circuit 18 is inputted to a circuit 19 through a DC cut capacitor 21. Since the capacitor 21 can enlarge an input impedance R of the circuit 19, a sufficient filter characteristic can is realized with a small capacity value.</p> |
