Abstract: 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.

Abstract: An amplifier, a circuit, and an optical communication system are provided. The disclosed amplifier may include a single-to-differential variable gain amplifier having a variable resistor switch that substantially always operates in a triode region at all time. Said another way, the resistor switch is configured to operate in a triode region regardless of whether or not a first portion of an input signal to the variable gain amplifier is larger than a second portion of the input signal. The disclosed scheme helps to keep the variable resistor switch in the triode region in all cases of operation, thereby maintaining the linearity condition and reducing distortion in the variable gain amplifier.

Abstract: An optical communication system, circuit, and Integrated Circuit (IC) chip are disclosed. The disclosed optical communication system includes a photodiode configured to receive light energy and convert the light energy into an electrical signal, an amplifier configured to receive the electrical signal from the photodiode and output an amplified electrical signal, and a control circuit comprising a biasing network that generates a modular logic level that scales with a bias voltage of the photodiode.

Abstract: A low-power, direct-drive EML driver circuit is provided that reduces power consumption by reducing the amount of current needed to create the necessary voltage swing in the drive signal. In addition, the EML driver circuit has an impedance matching network that has reduced complexity and that can be made at reduced costs compared to the impedance matching network of a typical EML driver circuit.

Abstract: An optical communication system, a circuit, and a method of operating an optical communication system are provided. The optical communication system is disclosed to include a photodiode configured to receive optical signals and convert the received optical signals into electrical signals, a Trans-Impedance Amplifier (TIA) electrically connected with the photodiode such that the TIA receives the electrical signals from the photodiode and is configured to convert the electrical signals received from the photodiode into amplified electrical signals, and a feedback loop connected between an input of the TIA and an output of the TIA that includes a switchable capacitor bank connected thereto which introduces at least one zero into a feedback factor transfer function of the TIA thereby tuning out poles or equalizing delay introduced by a TIA input network connected between the photodiode and the input of the TIA.

Abstract: A current mirror circuit is provided that has a feedback loop that includes a current mirror that provides base current compensation to the bases of the input and output transistors of the current mirror circuit. By employing a current mirror in the feedback loop to provide base current compensation, the minimum power supply voltage of the current mirror circuit is very low, typically less than or equal to about 1.5 V.

Abstract: A current mirror circuit is provided that has a feedback loop that includes a current mirror that provides base current compensation to the bases of the input and output transistors of the current mirror circuit. By employing a current mirror in the feedback loop to provide base current compensation, the minimum power supply voltage of the current mirror circuit is very low, typically less than or equal to about 1.5 V.

Abstract: Compact component arrangements that can be incorporated into integrated circuits are disclosed. In each of these compact component arrangements, a pitch parameter of a first set of components is used to define a pitch parameter of a second set of components that is to be interconnected with the first set of components. In some example embodiments, the first set of components is a set of optical devices and the second set of components is a set of interface circuits (for example, transmitter circuits or receiver circuits). In other example embodiments, the first set of components is the set of interface circuits and the second set of components is a set of synchronizing circuits each of which can be used for example, to retime an electrical signal that is provided to a respective one of the set of interface circuits.

Abstract: A transmitter is disclosed as being configured to encode optical signals in accordance with a multi-level coding scheme. The transmitter includes an Integrated Circuit architecture and partition that relaxes the bandwidth and linearity constraints of a gearbox-to-laser driver interface. In the proposed architecture, the gearbox Integrated Circuit aligns two or more digital data streams and transmits the aligned two or more data streams to the laser driver via separate signals.

Abstract: A gearbox IC is incorporated into an optical communications system to enable an optical link that incorporates the system to achieve data rates that are at least double that which are currently achievable in optical links. The gearbox IC is compatible with ASIC designs currently used in optical fiber links. The gearbox IC enables the data rate of the optical fiber link to be dramatically increased without requiring a redesign of the ASIC that is currently used in the optical fiber link. The gearbox IC performs data rate conversion and phase alignment for bit streams being transferred via the gearbox IC between the ASIC and an optical transceiver module of the optical communications system.

Abstract: A Tx IC and an Rx IC that use different supply voltages are mounted on a circuit board and interfaced via traces of the board. The configuration of the Tx IC is such that DC decoupling is provided between the ICs while also preventing inadvertent turn-on of the ESD diodes of the Rx IC. These features make it possible to provide DC decoupling between high-performance Tx ICs that use relatively high supply voltages and Rx ICs that use relatively low supply voltages without the need for AC coupling capacitors and while also preventing ESD protection of the Rx IC from being degraded.

Abstract: A transmitter is disclosed as being configured to encode optical signals in accordance with a multi-level coding scheme. The transmitter includes an Integrated Circuit architecture and partition that relaxes the bandwidth and linearity constraints of a gearbox-to-laser driver interface. In the proposed architecture, the gearbox Integrated Circuit aligns two or more digital data streams and transmits the aligned two or more data streams to the laser driver via separate signals.

Abstract: An equalizer that includes equalizer circuitry, a mean squared error (MSE) system, and adaptive control logic includes features that inhibit undesirable convergence to local minima.

Abstract: A connector assembly is provided that mates on one side with an optical transceiver module holder and that electrically connects on the opposite side with an external system circuit board. When the connector assembly is mated with an optical transceiver module holder, a base of a parallel optical transceiver module held in the holder mates with a socket of the connector assembly such that respective arrays of electrical contacts disposed on the base and in the socket come into contact with one another. At least one gearbox IC for performing data rate conversion is mounted on the assembly circuit board. A lower surface of the assembly circuit board has an array of electrical contacts on it that are in contact with an array of electrical contacts disposed on the surface of the external system circuit board on which the connector assembly is mounted.

Abstract: An optical communications system and method at least doubles the data rate of the optical fiber link without requiring a redesign of the backplane ASIC. This is made possible in part through the incorporation of at least one gearbox integrated circuit (IC) is incorporated into the system that is compatible with the current ASIC design. The gearbox IC receives N lanes of electrical data signals from the ASIC, with each electrical data signal having a data rate of X Gbps, and outputs N/2 lanes of electrical data signals, with each electrical data signal having a data rate of 2X Gbps. The high-speed optical transceiver module receives the N/2 electrical data signals output from the gearbox IC and produces N/2 respective optical data signals having a data rate of 2X Gbps for transmission over the optical fiber link.

Abstract: A rate-adaptive equalizer automatically initializes its tap coefficients to values. During an initialization process, a linear search algorithm is performed that sweeps the tap coefficients through different combinations of tap coefficients while assessing information about an eye associated with an input signal received over a communications channel. When the eye information indicates that the eye is open, the current tap coefficients are selected as the initial tap coefficients to be used at the beginning of the main adaptation algorithm.

Abstract: A Tx IC and an Rx IC that use different supply voltages are mounted on a circuit board and interfaced via traces of the board. The configuration of the Tx IC is such that DC decoupling is provided between the ICs while also preventing inadvertent turn-on of the ESD diodes of the Rx IC. These features make it possible to provide DC decoupling between high-performance Tx ICs that use relatively high supply voltages and Rx ICs that use relatively low supply voltages without the need for AC coupling capacitors and while also preventing ESD protection of the Rx IC from being degraded.

Abstract: A rate-adaptive equalizer automatically initializes its tap coefficients to values. During an initialization process, a linear search algorithm is performed that sweeps the tap coefficients through different combinations of tap coefficients while assessing information about an eye associated with an input signal received over a communications channel. When the eye information indicates that the eye is open, the current tap coefficients are selected as the initial tap coefficients to be used at the beginning of the main adaptation algorithm.

Abstract: A gearbox IC is incorporated into an optical communications system to enable an optical link that incorporates the system to achieve data rates that are at least double that which are currently achievable in optical links. The gearbox IC performs data rate conversion and phase alignment. In the transmit direction, the gearbox IC receives N lanes of electrical data signals having a data rate of X Gbps and outputs N/2 lanes of electrical data signals having a data rate of 2X Gbps. In the receive direction, the gearbox IC receives N/2 electrical data signals having a data rate of 2X Gbps and converts the N/2 electrical data signals into N electrical data signals having a data rate of X.

Abstract: An optical communication system, a transmitter, a receiver, and methods of operating the same are provided. In particular, a transmitter is disclosed as being configured to encode optical signals in accordance with a multi-level coding scheme. The receiver is configured to provide receive and decode to the optical signals received from the transmitter. One or both of the receiver and transmitter are configured to compensate for non-idealities or non-linearities introduced into the communication system by optical components of the system.