| 摘要 |
PROBLEM TO BE SOLVED: To obtain a reproduced wave that always defines the middle point of amplitude as its identification level regardless of the amplitude value of an optical signal to be inputted by shifting the output voltage from each other by 1/2 difference of pulse peak voltage and defining the crossing between the output voltage as the middle point of amplitude of a pulse signal to identify the crossing voltage. SOLUTION: The resistances R1, R2, R3 and R4 of a resistance circuit network 4 are connected to output V- to a differential trans-impedance amplifier 2, output Vpr+ of a switch circuit 5, output V+ of the amplifier 2 and output Vpr- of a switch circuit 5' respectively. Then a voltage addition operation is carried out and accordingly the voltage ((V+)+(Vp-))/2 and ((V-)+(Vp+))/2 are inputted to the input terminal of an identifier 3. The differential input signal of the amplifier 3 always crosses the middle point of amplitude at and after the rise of the first pulse input, and the output which inverts the output logical level by the crossing inversion of voltage is turned into an output waveform that is delayed by a degree equal to an internal response delay. |
