Patent ID: 7787781
Filing Date: 2010-08-31
Classification: H04B

Abstract:
1. An optical receiver comprising: a light-emitting device for receiving an optical signal and converting the optical signal into a corresponding photo-current; a pre-amplifier for converting the photo-current into an electrical signal; and a detector for detecting, based on an output of the pre-amplifier, a decrease of intensity of the optical signal, said detector being coupled with the pre-amplifier through a coupling capacitor, wherein the detector includes, a bottom hold configured to detect and hold a minimum level of the output of the pre-amplifier, a peak hold configured to detect and hold a maximum level of the output of the pre-amplifier, a first comparator configured to generate, by comparing an output of the bottom hold with a first reference, a first alarm when the output of the pre-amplifier is greater than the first reference, a second comparator configured to generate, by comparing an output of the peak hold with a second reference, a second alarm when the output of the peak hold is less than the second reference, and a selector configured to select one of the first alarm and the second alarm and to output an alarm signal in accordance with a state of the alarm signal output from the selector, wherein said alarm signal selected by said selector switches said selector so as to select the other of the first alarm and the second alarm.