SIGNAL DETECTION CIRCUIT FOR OPTICAL RECEIVER IN AN OPTICAL COMMUNICATION SYSTEM

摘要

An SD circuit for detecting an optical receiver in an optical communications system which respects the imprecision of the SD discrimination is provided to determine SD accurately due to reducing the difference of SD circuit for an optical receiver in the optical communications system. A top hold circuit(631) detects the high level of the input signal inputted to an SD circuit(630). An AOC(Automatic Offset Cancellation) circuit outputs the offset of the output signal of LA(Limiting Amplifier)(610) and DC(Direct Current) value. The voltage source addition circuit is connected to the output terminal of the AOC circuit. A voltage source addition circuit receives the output signal of the AOC circuit. The voltage source addition circuit outputs reference voltage by adding the AOC circuit output value to Vth value. A comparator(633) comprises two input terminals. A first input terminal is connected to the output terminal of the top hold circuit. A second input terminal is connected to the output terminal of the voltage source summing circuit.