An optical communication system, a linear optical receiver, and an Integrated Circuit (IC) chip are disclosed, among other things. One example of the disclosed IC chip includes a transimpedance amplifier that receives an input electrical signal from a photodiode and provides an amplified version of the input electrical signal as an output, at least one variable gain amplifier that receives the amplified electrical signal output by the transimpedance amplifier and a bandwidth control mechanism that extends a bandwidth of the second amplified output at a maximum gain of the second amplification phase and also reduces a peaking of the second amplified output at a minimum gain of the second amplification phase.

It is disclosed an optical coherent receiver for an optical communication network. The optical coherent receiver is configured to receive a modulated optical signal and to process it for generating an in-phase component and a quadrature component. The optical coherent receiver comprises a power adjuster in turn comprising a multiplying unit and a retroactively connected digital circuit. The multiplying unit is configured to multiply the in-phase and quadrature components by in-phase and quadrature gains, respectively, thereby providing power-adjusted in-phase and quadrature components. The digital circuit is configured to compute: a common gain indicative of a sum of the powers of the power-adjusted in-phase and quadrature components; a differential gain indicative of a difference between the powers of the power-adjusted in-phase and quadrature components; and the in-phase and quadrature gains as a product and a ratio, respectively, between the common gain and the differential gain.

A method for dynamic sizing of a blocker margin by a receiver automatic gain control (AGC) is described. The method includes measuring a wanted signal level and a blocker signal level. The method also includes adjusting a linear target for the wanted signal level at the output of an analog-to-digital converter (ADC) of the receiver based on the blocker signal level. The linear target is adjusted to optimize a wanted signal signal-to-noise ratio (SNR) and the blocker margin. The method further includes adjusting a receiver front-end gain based on the adjusted linear target.

Methods and systems for a distributed optoelectronic receiver are disclosed and may include an optoelectronic receiver having a grating coupler, a splitter, a plurality of photodiodes, and a plurality of transimpedance amplifiers (TIAs). The receiver receives a modulated optical signal utilizing the grating coupler, splits the received signal into a plurality of optical signals, generates a plurality of electrical signals from the plurality of optical signals utilizing the plurality of photodiodes, communicates the plurality of electrical signals to the plurality of TIAs, amplifies the plurality of electrical signals utilizing the plurality of TIAs, and generates an output electrical signal from coupled outputs of the plurality of TIAs. Each TIA may be configured to amplify signals in a different frequency range. One of the plurality of electrical signals may be DC coupled to a low frequency TIA of the plurality of TIAs.

An automatic gain controller comprises an amplifier including a variable gain. A resonant low-pass filter includes an input coupled to an output of the amplifier. The resonant low-pass filter is a second order low-pass filter. The second order low-pass filter includes a Sallen-Key topology. The Sallen-Key topology comprises a quality factor between 1.4 and 1.6. A threshold detection circuit includes an input coupled to an output of the second order low-pass filter to compare an output signal of the second order low-pass filter to a threshold and an output of the threshold detection circuit coupled to control the variable gain of the amplifier. A state machine is coupled between the output of the threshold detection circuit and the amplifier. The state machine is configured to transition based on a current state of the state machine. The resonant low-pass filter exhibits overshoot to trigger a hysteresis of the threshold detection circuit.

A method and circuit are provided for implementing enhanced CMOS inverter based optical Transimpedance Amplifiers (TIAs). A transimpedence amplifer (TIA) includes a photo-detector, and the TIA is formed by a first TIA inverter and a second TIA inverter. The first TIA inverter has an input from a cathode side of the photo-detector and the second inverter has an input from an anode side of the photo-detector. A replica TIA is formed by two replica inverters, coupled to a respective input to a first operational amplifier and a second operational amplifier. The first operational amplifier and the second operational amplifier have a feedback configuration for respectively regulating a set voltage level at the cathode side of the photo-detector input of the first inverter and at the anode side of the photo-detector input of the second inverter.

An amplifier, a circuit, and an optical communication system are provided. The disclosed amplifier may include a first transistor receiving a first portion of an input signal received at the amplifier, a second transistor receiving a second portion of the input signal, an automatic gain control signal that is dynamically adjustable in response to variations in an output of the amplifier, and a varactor that has its capacitance adjusted by changes in the automatic gain control signal and, as a result, adjusts a position of a pole in a transfer function of the amplifier.

An optical communication system, a linear optical receiver, and an Integrated Circuit (IC) chip are disclosed, among other things. One example of the disclosed IC chip includes a transimpedance amplifier that receives an input electrical signal from a photodiode and provides an amplified version of the input electrical signal as an output, at least one variable gain amplifier that receives the amplified electrical signal output by the transimpedance amplifier and a bandwidth control mechanism that extends a bandwidth of the second amplified output at a maximum gain of the second amplification phase and also reduces a peaking of the second amplified output at a minimum gain of the second amplification phase.

A driver that drives an optical device, such as laser diode (LD) and/or optical modulator, is disclosed. The driver includes a variable gain amplifier (VGA) and a post amplifier. The post amplifier amplifies an output of the VGA to a preset amplifier as varying the gain of the VGA. The VGA includes two differential pairs each amplify the input signal oppositely in phases thereof and outputs of the differential pairs are compositely provided to the post amplifier. The gain of the VGA is varied by adjusting contribution of the second differential pair to the output of the VGA.

A gain-variable trans-impedance amplifier (TIA) in optical device is disclosed. The TIA has an improved dynamic range for receiving electrical signals and is configured to convert current signals from an avalanche photodiode (APD) to voltage signals. A resistor element is between the input and output terminals of the TIA, wherein the resistance of the resistor element can regulate the resistance and/or impedance value of the TIA, and a switch determines or controls the resistance of the resistor element. When the power of an optical signal received by the APD is higher than a predetermined value, the resistance becomes smaller and the gain of the TIA becomes greater. When the power of the optical signal is lower than the predetermined value, the resistance becomes greater. The gain of the TIA is automatically adjusted on the basis of the intensity of received optical signals to obtain a greater dynamic operational range.