US 12,537,604 B2Granted

Techniques to facilitate automatic gain control for an optical receiver

AssigneeCisco Technology, Inc.

InventorsAlexander C. Kurylak, Sanjay Sunder, Pratiksh Parikh, Jenjen Tiao, Bibhu P. Das, Kadaba Lakshmikumar

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Abstract

Provided herein are techniques to facilitate automatic gain control for an optical receiver. In one example, a method may include for a first mode, first adjusting, for a received optical input signal, at least one of: a coarse gain of a programmable gain amplifier (PGA), a fine gain of the PGA, or an attenuation of a variable optical attenuator (VOA) until a voltage swing peak value of an output signal of the optical receiver satisfies a first voltage swing peak range. The method may further include, through a second mode, triggering second adjusting of at least one of the VOA attenuation or the PGA fine gain based on determining that the voltage swing peak value of the output signal does not satisfy a second voltage swing peak range or that another voltage swing peak value obtained from an external signal processing device does not satisfy another voltage swing peak range.

Claims20

Dependent claims

A method for operating an optical receiver comprising a variable optical attenuator (VOA) that receives an optical input signal, a transimpedance amplifier (TIA), a programmable gain amplifier (PGA), and a controller, the method comprising:

for a first operational mode, first adjusting, by the controller for the received optical input signal, at least one of:
a coarse gain of the PGA, a fine gain of the PGA, or an attenuation of the VOA until a voltage swing peak value of an output signal of the optical receiver satisfies a first voltage swing peak range that is based on a target voltage swing peak value, wherein the output signal of the optical receiver is derived from an output of the PGA and the output signal is provided to an external signal processing device;
and
upon the voltage swing peak value of the output signal of the optical receiver satisfying the first voltage swing peak range, maintaining the coarse gain of the PGA and performing, by the controller, operations for a second operational mode, comprising:
triggering second adjusting of at least one of the attenuation of the VOA or the fine gain of the PGA based on one of:
determining that the voltage swing peak value of the output signal does not satisfy a second voltage swing peak range that is based on the target voltage swing peak value;
or
determining that an external voltage swing peak value obtained by the controller from the external signal processing device does not satisfy an external voltage swing peak range that is obtained by the controller from the external signal processing device;
or
maintaining the attenuation of the VOA and the fine gain of the PGA if no second adjusting is triggered for the second operational mode.

7 more elements

An optical receiver comprising:

an optical circuit portion comprising a variable optical attenuator (VOA) connected with a photodetector, wherein the VOA receives an optical input signal;
an electrical circuit portion comprising a transimpedance amplifier (TIA) that is connected to an output of the photodetector, a programmable gain amplifier (PGA) connected to an output of the TIA, and an output driver connected to an output of the PGA that is to generate an output signal of the optical receiver that is to be provided to an external signal processing device;
and
a controller that is to manage an attenuation of the VOA and at least one of a coarse gain of the PGA or a fine gain of the PGA, wherein the controller comprises at least one memory element for storing data and at least one processor for executing instructions associated with the data, wherein executing the instructions causes the controller to perform operations, comprising:
for a first operational mode, first adjusting, by the controller for the received optical input signal, at least one of:
a coarse gain of the PGA, a fine gain of the PGA, or an attenuation of the VOA until a voltage swing peak value of an output signal of the optical receiver satisfies a first voltage swing peak range that is based on a target voltage swing peak value;
and
upon the voltage swing peak value of the output signal of the optical receiver satisfying the first voltage swing peak range, maintaining the coarse gain of the PGA and performing, by the controller, operations for a second operational mode, comprising:
triggering second adjusting of at least one of the attenuation of the VOA or the fine gain of the PGA based on one of:
determining that the voltage swing peak value of the output signal does not satisfy a second voltage swing peak range that is based on the target voltage swing peak value;
or
determining that an external voltage swing peak value obtained by the controller from the external signal processing device does not satisfy an external voltage swing peak range that is obtained by the controller from the external signal processing device;
or
maintaining the attenuation of the VOA and the fine gain of the PGA if no second adjusting is triggered for the second operational mode.

11 more elements

One or more non-transitory computer readable storage media encoded with instructions that, when executed by a controller of an optical receiver, cause the controller to perform operations, comprising:

for a first operational mode, first adjusting, by the controller for a received optical input signal, at least one of:
a coarse gain of a programmable gain amplifier (PGA), a fine gain of the PGA, or an attenuation of a variable optical attenuator (VOA) until a voltage swing peak value of an output signal of the optical receiver satisfies a first voltage swing peak range that is based on a target voltage swing peak value, wherein the output signal of the optical receiver is derived from an output of the PGA and the output signal is provided to an external signal processing device;
and
upon the voltage swing peak value of the output signal of the optical receiver satisfying the first voltage swing peak range, maintaining the coarse gain of the PGA and performing, by the controller, operations for a second operational mode, comprising:
triggering second adjusting of at least one of the attenuation of the VOA or the fine gain of the PGA based on one of:
determining that the voltage swing peak value of the output signal does not satisfy a second voltage swing peak range that is based on the target voltage swing peak value;
or
determining that an external voltage swing peak value obtained by the controller from the external signal processing device does not satisfy an external voltage swing peak range that is obtained by the controller from the external signal processing device;
or
maintaining the attenuation of the VOA and the fine gain of the PGA if no second adjusting is triggered for the second operational mode.

7 more elements

Dependencies are inferred from the claim text.