| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a high-speed optical coupling device capable of manufacturing at a low cost without increasing a circuit scale even when using a light emitting diode with the limitation on the response of optical output. <P>SOLUTION: In the constitution of connecting a threshold level variable circuit 14 between the output of a trans-impedance amplifier circuit 18 and the input of a comparator 15, the threshold level variable circuit 14 is constituted of a constant current source 21 normally outputting a first reference electrical signal as a reference electrical signal, a constant current source 22 outputting a second reference electrical signal at the time of the rise of an input electrical signal from an input signal conversion means, a comparator 24 controlling the operation of the constant current source 22 and a resistor 23 for adjustment offsetting the reference electrical signal to the input electrical signal. Thus, an offset voltage is easily generated without increasing the circuit scale. <P>COPYRIGHT: (C)2003,JPO |
