| 摘要 |
PROBLEM TO BE SOLVED: To obtain a device that demodulates a pulse signal in a short wait time by generating an envelope signal from an envelope of an amplified signal obtained by amplifying an ASK data signal and extending the pulse width of the pulse signal obtained by comparing the envelope signal with a prescribed threshold to be the same as the pulse width of the ASK data signal. SOLUTION: An ASK demodulator 11 uses a photo diode 15 to receive an ASK optical signal and generates a DC current with a magnitude nearly proportional to intensity of light. A front stage amplifier 19 amplifies this current. An output signal from the front stage amplifier 19 is fed to a tuning amplifier 23, where it is amplified. An edge detector 27 receives the amplified signal outputted from the tuning amplifier 23. A comparator 31 receives an envelope signal outputted from the edge detector 27 and compares the envelope signal with a prescribed threshold to produce an output pulse signal. A pulse stretcher circuit 35 receives the output pulse signal from the comparator 31 and a buffer circuit 41 receives a series of the output pulses to generate the output signal of the ASK demodulator 11. |
