| 摘要 |
PURPOSE:To reduce the power consumption of a DC supplying circuit for subscriber circuits, by setting the stand-by power of a differential amplifier or its corresponding amplifier to zero or a value close to zero. CONSTITUTION:Assuming that a current amplifier consists of resistors 32, 33 and transistors (TRs) 37, 38 and 31 and the current amplification factor of each TR is high and each base current is negligible in its operation, an input current from a terminal 35 flows to the resistor 33, and an input current from a terminal 34 and an output current from a terminal 36 flow to a terminal 34, then the current amplification factor of the entire circuit is given with the resistance ratio of the resistors 32 and 33 only. The current flowing to the TRs 37, 38 and the resistor 33 is respectively equal to the input currents from the terminals 34 and 35 and the current flowing to the TR31 and the resistor 32 is proportional to the input current, then the input current is made to zero, each operating current becomes zero, allowing to zero the power consumption at stand-by. |
