US 4,229,831 AGranted

Drift compensated fiber optic-receiver

AssigneeBurroughs Corporation

InventorWilliam A. Lacher

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Abstract

The present disclosure describes an electronic circuit for use as a receiver in digital fiber-optic systems. It is the nature of such systems that considerable amplification is required at the receiving terminus to bring to useful signal levels the electrical energy provided by photodetectors in response to the light incident thereupon. However, the photodetectors and amplifiers themselves contribute noise currents which vary with temperature and operational amplifiers have a characteristic initial dc offset. Accordingly, while receivers for fiber-optic systems have been complicated and expensive, the receiver of the present invention is neither of these. It amplifies the small signals from the photodetector to a suitable level, eliminates the effects of the aforementioned dc offset, rejects any long-term drift and provides output signals of any duration from a bistable stage, which signals correspond to the original digital information transmitted by the system.

Claims7

Dependent claims

A receiver for use in a fiber-optic system for the transmission of digital data comprising:

photodetector means responsive to the transmitted light incident thereupon for generating electrical pulses corresponding respectively to said digital data,
amplifier means coupled to said photodetector means for amplifying said electrical pulses to a predetermined level,
differentiator means coupled to said amplifier means for differentiating the amplified electrical pulses, thereby providing with respect to a reference potential a pair of signals of opposite polarity for each amplified pulse,
a pair of comparator means coupled to said differentiator means and biased to respective opposite polarities, each of said pair of comparator means providing an output pulse in response to one of said pair of signals of opposite polarity from said differentiator means,
flip-flop means having at least a "1" and a "0" input terminal and a "1" output terminal, means coupling the output pulses of one of said pair of comparator means to said "1" input terminal and the output pulses of the other of said pair of comparator means to said "0" input terminal, the switching of said flip-flop means from one stable state to its opposite state in response to the pulses applied alternately to its "1" and "0" input terminals generating output signal waveforms on said "1" output terminal which are of a predetermined usable amplitude and which correspond directly to said digital data transmitted optically by said system.

2 more elements

Dependencies are inferred from the claim text.