Push-pull optical receiver having gain control
AssigneeScientific-Atlanta, Inc.
InventorsFrank R. Little, Herman A. Kruse, John G. Megna, Rezin E. Pidgeon
Life of this patent
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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.
Claims10
An optical receiver circuit for an incoming optical signal having broadband radio frequency amplitude modulation, said 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 means for amplifying said electrical signal;
- second means for amplifying said electrical signal;
- said first amplifying means and said second amplifying means each comprising a transimpedance amplifier stage including a first field effect transistor having a gate terminal, a drain terminal and a source terminal, each of said gate terminals being connected to a terminal of said optical detector and each drain terminal being connected to the gate terminal of the same field effect transistor through a selectable feedback resistor;
- means for coupling said first amplifying means and said second amplifying means in a push-pull relationship;
- said first amplifying means and said second amplifying means each further comprising a high impedance buffer amplifier stage having an input terminal connected to the drain terminal of its respective transimpedance amplifier stage and an output terminal connected to a terminal of said push-pull coupling means;
- a gain control circuit responsive to a control signal for varying a gain of said first amplifying means and second amplifying means;
- and
- wherein the high impedance buffer amplifier stages of said first and second amplifying means each comprise a second field effect transistor having a drain terminal connected to a terminal of said push-pull coupling means, a gate terminal connected to the drain terminal of said first field effect transistor and a source terminal connected to said gain control circuit.
An amplifier adapted to amplify a signal generated by an optical detector which varies with an optical signal power level applied to the detector, said amplifier comprising:
- first means for amplifying said signal;
- second means for amplifying said signal;
- said first amplifying means and said second amplifying means each comprising a transimpedance amplifier stage including a field effect transistor having a gate terminal, a drain terminal and a source terminal, each of said gate terminals being connected to an input terminal of said amplifier and each drain terminal being connected to the gate terminal of the same field effect transistor through a selectable feedback resistor;
- means for coupling said first amplifying means to said second amplifying means in a push-pull relationship;
- said first amplifying means and said second amplifying means each further comprising a high impedance buffer amplifier stage having an input terminal connected to the drain terminal of the respective transimpedance amplifier stage and an output terminal connected to a terminal of said push-pull coupling means;
- a gain control circuit responsive to a control signal for varying the gain of said first and second amplifying means;
- and
- wherein the high impedance buffer amplifier stages of said first and second amplifying means each comprise a second field effect transistor having a drain terminal connected to a terminal of said push-pull coupling means, a gate terminal connected to the drain of said first field effect transistor and a source terminal connected to said gain control circuit.
An optical receiver circuit for an incoming optical signal having broadband radio frequency amplitude modulation, said 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 means for amplifying said electrical signal;
- second means for amplifying said electrical signal;
- said first amplifying means and said second amplifying means each comprising a transimpedance amplifier stage including a first field effect transistor having a gate terminal, a drain terminal and a source terminal, each of said gate terminals being connected to a terminal of said optical detector and each drain terminal being connected to the gate terminal of the same field effect transistor through a selectable feedback resistor;
- means for coupling said first amplifying means and said second amplifying means in a push-pull relationship;
- and
- a gain control circuit responsive to a control signal for varying a gain of said first amplifying means and second amplifying means.
An amplifier adapted to amplify a signal generated by an optical detector which varies with an optical signal power level applied to the detector, said amplifier comprising:
- first means for amplifying said signal;
- second means for amplifying said signal;
- said first amplifying means and said second amplifying means each comprising a transimpedance amplifier stage including a field effect transistor having a gate terminal, a drain terminal and a source terminal, each of said gate terminals being connected to an input terminal of said amplifier and each drain terminal being connected to the gate terminal of the same field effect transistor through a selectable feedback resistor;
- means for coupling said first amplifying means to said second amplifying means in a push-pull relationship;
- and
- a gain control circuit responsive to a control signal for varying a gain of said first and second amplifying means.
Dependencies are inferred from the claim text.