Light reception circuit capable of receiving large level optical signal
OwnerTadayuki Chikumainventor
Life of this patent
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Abstract
A pin photo-diode 13 is used as a light reception device. When an input revel detection circuit 14 detects that an electrical signal outputted from pin photo-diode 13 exceeds a predetermined level, a transmittivity of an EA device 11 is dropped through an EA control circuit 12, and an externally supplied optical input signal is inputted through the EA device 11 to the pin photo-diode 13. Accordingly, a level of an optical signal to be inputted to the pin photodiode 13 can be always reduced to the predetermined level or less without any mount of an input protection circuit and without any usage of two EA devices.
Claims11
A light reception circuit comprising:
- an optical signal level variable device which receives an optical input signal externally supplied;
- a light reception device which converts an optical signal supplied from said optical signal level variable device into an electrical signal;
- a detection circuit which detects whether or not the electrical signal outputted from said light reception device exceeds a predetermined level;
- and
- a control circuit which changes a transmittivity of said optical signal level variable device based on the detection result of said detection circuit.
Dependencies are inferred from the claim text.