Push-pull optical receiver having gain control
AssigneeScientific-Atlanta, Inc.
InventorsFrank R. Little, Herman A. Kruse, John G. Megna, Rezin E. Pidgeon
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Abstract
A receiver is described for optical signals which are amplitude modulated with broadband radio frequency signals. The receiver includes an optical detector which receives the incoming optical signal and generates a radio frequency electrical signal which varies with the power level of the incoming optical signal. This electrical signal is applied to a pair of amplifiers which are connected in a push-pull relationship. A gain control circuit controls the gain of the amplifier pair.
Claims12
An optical receiver circuit for an incoming optical signal having broadband radio frequency amplitude modulation, the circuit comprising:
- an optical detector for receiving said optical signal and generating therefrom an electrical signal which varies with the optical signal power level;
- first and second amplifiers, connected in a push-pull relationship, for amplifying said electrical signal, said first and second amplifiers each comprising a transimpedance amplifier including selector circuitry for selecting an input impedance of said transimpedance amplifier;
- and
- a gain control circuit for varying a gain of said first and second amplifiers.
An amplifier adapted to amplify a signal generated by an optical detector which varies with an optical signal power level applied to the optical detector, said amplifier comprising:
- first and second amplifiers connected in a push-pull relationship, each of said first and second amplifiers comprising a transimpedance amplifier including a selector circuit for selecting an input impedance of said transimpedance amplifier;
- and
- a gain control circuit for varying the gain of said first and second amplifiers.
An optical receiver circuit for an incoming optical signal having broadband radio frequency amplitude modulation, the circuit comprising:
- a photodiode, having first and second terminals, for receiving the incoming optical signal and for generating therefrom an electrical signal across said first and second terminals that varies with the optical signal power level;
- first and second transimpedance amplifier stages coupled to said first and second terminals of said photodiode, respectively;
- first and second buffer amplifier stages connected in push-pull relationship, said first and second buffer amplifiers being coupled to said first and second transimpedance amplifier stages, respectively;
- and
- a gain control circuit for controlling the gain at an output terminal, said gain control circuit having a first terminal coupled to said output terminal, a second terminal coupled to said first buffer amplifier stage, and a third terminal coupled to said second buffer amplifier stage.
Dependencies are inferred from the claim text.