| 摘要 |
PROBLEM TO BE SOLVED: To generate the output signal only for an input signal having a high level without generating an output signal for the input signal having a low level by comparing the level of an output terminal voltage with that of a second reference voltage and supplying an output current corresponding to the difference to an output terminal. SOLUTION: When the output current of a signal current source 1 is in the no-signal state of 0, the voltage of an output terminal 4 becomes a DC voltage Vref of a first reference voltage source 3. Consequently, the voltage Vref is applied to the base of a transistor TR 8 of a comparator, and the comparator 5 enters the balanced state, and collector currents of TRs 7 and 9 are made equal, and there is not a current from a point A to a resistor 6 or a reverse current, and the comparator 5 doesn't have an influence upon the voltage of the output terminal 4. When the output current of the signal current source 1 has a high level, the voltage of the output terminal 4 is generated in the direction and the quantity of the supply input current and the comparator 5 is immediately operated, but its influence is ignored if the current value of an operation current source 1-of the comparator 5 is made sufficiently smaller than the output current of the signal current source 1. |
