The invention presents an equalizing device, a corresponding method and an optical signal with a frame structure for enabling the method. The equalizing device includes a first 2×2 MIMO equalizer configured to perform a first equalization on the digital signal, supported by a 2×2 MIMO channel estimation of the channel based on the digital signal. Further, the device includes a second 2×2 MIMO equalizer, arranged after the first equalizer and configured to perform a second equalization on the digital signal, supported by a State of Polarization (SOP) estimation of the optical signal based on the digital signal.

Various example embodiments of the present disclosure relates to a physical layer, PHY, circuitry for an optical line terminal, OLT, the PHY circuitry being configured to receive a control signal including an identification of a transmitting ONT for pre-loading an equalization configuration associated with the identification of the transmitting ONT. Other example embodiments relate to a medium access control, MAC, circuitry for OLT, the MAC circuitry being configured to determine an upstream allocation map for optical network terminals, ONTs, and to generate a control signal for a PHY circuitry including synchronization information for receiving upstream optical signal bursts from a transmitting ONT and an identification of the transmitting ONT based on the upstream allocation map. Further example embodiments related to an optical line terminal, OLT, and a method therefor.

Lateral and vertical microstructure enhanced photodetectors and avalanche photodetectors are monolithically integrated with CMOS/BiCMOS ASICs and can also be integrated with laser devices using fluidic assembly techniques. Photodetectors can be configured in a vertical PIN arrangement or lateral metal-semiconductor-metal arrangement where electrodes are in an inter-digitated pattern. Microstructures, such as holes and protrusions, can improve quantum efficiency in silicon, germanium and III-V materials and can also reduce avalanche voltages for avalanche photodiodes. Applications include optical communications within and between datacenters, telecommunications, LIDAR, and free space data communication.

An illustrative receiver includes: a decision element that derives symbol decisions from a slicer input signal; an equalizer that converts a receive signal into the slicer input signal; a summer that combines the symbol decisions with the slicer input signal to produce an error signal; and a level finder that operates on said signals to determine thresholds at which each signal has a given probability of exceeding the threshold. One illustrative level finder circuit includes: a gated comparator and an asymmetric accumulator. The gated comparator asserts a first or a second gated output signal to indicate when an input signal exceeds or falls below a threshold with a programmable condition being met. The asymmetric accumulator adapts the threshold using up steps for assertions of the first gated output signal and down steps for assertions of the second gated output signal, with the up-step size being different than the down-step size.

An illustrative receiver includes: a decision element that derives symbol decisions from a slicer input signal; an equalizer that converts a receive signal into the slicer input signal; a summer that combines the symbol decisions with the slicer input signal to produce an error signal; and a level finder that operates on said signals to determine thresholds at which each signal has a given probability of exceeding the threshold. One illustrative level finder circuit includes: a gated comparator and an asymmetric accumulator. The gated comparator asserts a first or a second gated output signal to indicate when an input signal exceeds or falls below a threshold with a programmable condition being met. The asymmetric accumulator adapts the threshold using up steps for assertions of the first gated output signal and down steps for assertions of the second gated output signal, with the up-step size being different than the down-step size.

The present invention is directed to communication methods and systems thereof. In a specific embodiment, a noise cancelation system includes a slicer that processes a data stream generates both PAM symbols and error data. An RIN estimator generates RIN data based on the PAM symbols and the error data. A filter removes non-RIN information from the RIN data. The filtered RIN data includes an offset term and a gain term, which are used to remove RIN noise from the data stream. There are other embodiments as well.

The present invention is directed to communication methods and systems thereof. In a specific embodiment, a noise cancelation system includes a slicer that processes a data stream generates both PAM symbols and error data. An RIN estimator generates RIN data based on the PAM symbols and the error data. A filter removes non-RIN information from the RIN data. The filtered RIN data includes an offset term and a gain term, which are used to remove RIN noise from the data stream. There are other embodiments as well.

An illustrative SerDes receiver includes: a front-end filter, a precomputation unit, a selection element, and a controller. The front end filter converts a receive signal into a linearly-equalized signal. The precomputation unit accepts the linearly-equalized signal with or without a subtracted feedback signal, and employs a set of comparators with threshold values that depend on a first post-cursor ISI value F.sub.1, the set of comparators operating to generate a set of tentative symbol decisions. The selection element derives a selected symbol decision from each set of tentative symbol decisions, thereby deriving a sequence of symbol decisions from the receive signal. The controller constrains F.sub.1 if the receive signal uses a PAM4 signal constellation, setting F.sub.1 to equal zero if the receive signal is conveyed via a low-loss channel and to equal one if the receive signal is conveyed via a high-loss channel.

A circuit and method for mitigating multi-path interference in direct detection optical systems is provided. Samples of an optical signal having a pulse amplitude modulated (PAM) E-field are processed by generating a PAM level for each sample. For each sample, the sample is subtracted from the respective PAM level to generate a corresponding error sample. The error samples are lowpass filtered to produce estimates of multi-path interference (MPI). For each sample, one of the estimates of MPI is combined with the sample to produce an interference-mitigated sample.

Embodiments include techniques for transmitting and receiving radio frequency (RF) signals, where the techniques for generating, via a digital analog converter (DAC), a frequency signal, and filtering the frequency signal to produce a first filtered signal and a second filtered signal. The techniques also include transmitting the second filtered signal to a device under test and filtering the second filtered signal into a sub-signal having one or more components. The techniques include mixing the first filtered signal with the sub-signal to produce a first mixed signal, subsequently mixing the first mixed signal with an output signal received from the device under test to produce a second mixed signal and converting the second mixed signal for analysis.