Optical receiver circuit including a filter network to minimize noise
AssigneeBritish Telecommunication, plc
InventorIan Garrett
Life of this patent
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Abstract
A receiver circuit for receiving a modulated optical signal and for generating a corresponding electrical signal comprises a photodiode (1) for receiving the optical signal and for generating a first modulated electrical signal. An amplification circuit (3) receives the first electrical signal or a signal related thereto via an n stage (where n is an odd-integer) filter network (2) connected between the photodiode (1) and the amplification circuit (3). The output from the amplification circuit is fed to a first equalization amd noise filter (5). The characteristics of the filter network are such that the total thermal noise power output of the first noise filter is substantially minimized.
Claims14
A receiver circuit for receiving a modulated optical signal and for generating a corresponding electrical signal, the circuit comprising a photodetector acting as a current source for generating a first modulated electrical signal;
- an amplification circuit to which the first electrical signal or a signal related thereto is fed;
- a first noise filter;
- and an n stage (where n is an odd integer 3) filter network connected between the detector and the amplification circuit, the characteristics of the filter network being such that the total thermal noise power output of the first noise filter is substantially minimised.
A circuit according to any of the preceding claims, wherein the photodetector comprises a photodiode.
A method of constructing a receiver circuit for receiving a modulated optical signal and for generating a corresponding electrical signal in which the circuit comprises a photodetector acting as a current source for generating a first modulated electrical signal;
- an amplification circuit to which the first electrical signal or a signal related thereto is fed;
- a first noise filter;
- and an n stage (where n is an odd integer .gtoreq.3) filter network connected between the detector and the amplification circuit, the method comprising selecting the components of the filter network such that the total thermal noise power output of the first noise filter is substantially minimised.
Dependencies are inferred from the claim text.