Burst Mode Linear Optical Receivers
First Claim
1. An optical receiver comprising:
- a photodetector to receive from an external optical fiber an information containing optical communications signal transmitted in time spaced signal bursts and converting such signal bursts into an electrical signal;
a first RF amplifier coupled to a first electrical output of the photodetector for generating a first output signal;
a second RF amplifier coupled to a second electrical output of the photodetector for generating a second output signal;
a capacitor having a capacitance of less than 200 pf and coupling the first electrical output to the first RF amplifier;
a biasing circuit connected to said first and second RF amplifiers for reverse biasing the photodetector; and
a combiner circuit coupled to the output of the first and second RF amplifiers for producing an RF output signal,wherein the gain of the amplifier is maintained at substantially the same level from approximately the beginning of a signal burst and continuing for a period of at least 100 microseconds after the beginning of the burst.
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Accused Products
Abstract
Techniques are provided for implementing a burst mode optical receiver capable of maintaining a stable gain profile in response to a burst signal. The optical receiver has a photodiode in balanced circuit configuration with a separate RF amplifier stage connected to each terminal of the photodiode. The two RF amplifier stages are coupled to biasing voltage sources that are inverted in comparison to the terminal connections and that, in some examples, each contain a field effect transistor (FET) that having a gate that is controlled in response to a sensed voltage. The burst mode optical receiver may be used in numerous applications, including optical line terminations (OLTs) in passive optical networks (PONs).
9 Citations
20 Claims
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1. An optical receiver comprising:
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a photodetector to receive from an external optical fiber an information containing optical communications signal transmitted in time spaced signal bursts and converting such signal bursts into an electrical signal; a first RF amplifier coupled to a first electrical output of the photodetector for generating a first output signal; a second RF amplifier coupled to a second electrical output of the photodetector for generating a second output signal; a capacitor having a capacitance of less than 200 pf and coupling the first electrical output to the first RF amplifier; a biasing circuit connected to said first and second RF amplifiers for reverse biasing the photodetector; and a combiner circuit coupled to the output of the first and second RF amplifiers for producing an RF output signal, wherein the gain of the amplifier is maintained at substantially the same level from approximately the beginning of a signal burst and continuing for a period of at least 100 microseconds after the beginning of the burst. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A burst mode optical receiver for receiving an information containing optical communications signal transmitted in time spaced signal bursts and converting such signal bursts into an electrical signal comprising:
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a photodetector having a positive terminal and a negative terminal; a first RF amplifier having a low voltage biasing source and coupled to the positive terminal for generating a first output signal; a second RF amplifier having a high voltage biasing source and coupled to the negative terminal for generating a second output signal; and a gate bias control circuit coupled to the first RF amplifier and the second RF amplifier, wherein the gate bias control circuit controls gain of each of the first and second RF amplifiers and is configured to, in response to a sensed voltage, maintain gain of the first RF amplifier and the second RF amplifier in response to a signal burst for a period of at least 100 microseconds after the beginning of the signal burst. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification