Palo Alto, CA, United States
Palo Alto, CA, United States
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Time filter
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A method for performing background calibration of interleave timing errors in N order Time-Interleaved Analog to Digital Converters (TIADCs), according to which N samples of the input signal are acquired in N different phases and the time-interleave error of each phase is calculated. Then the sign of each of the time-interleave error is extracted and the errors are adjusted by adjusting the timing of erroneous phases. This process is repeated until all the errors are lower than a predefined level.


An optical modulator with a region with non-linear characteristics with optimized BER performance, which comprises circuitry for adjusting the spacing between power levels of optical signals at the output of the optical modulator by adjusting the bias point of the optical modulator to be closer to a nonlinear region of the modulator, such that modulating signals having lower power will be compressed by the nonlinear region more than modulating signals having higher power. During adjustment, larger spacing between higher power levels of optical signals is introduced at the output of the optical modulator and lower spacing between lower power levels of optical signals is introduced at the output of the optical modulator.


System and method for the calibration of interleave time errors in an n-level PAM Digital to Analog Converter (DAC), according to which a set of two samplers with adjustable sample time and threshold are introduced at the output of the DAC, which are separated in time. The set of samplers is swept through a n unit interval (UI) window and the n-UI window is classified to periods of transitions and non-transitions on an eye diagram. The relative timing of the lower rate clocks into an n:1 multiplexer is controlled using a control loop, to force equal eye width within the n-UI window and the interleaved timing errors are measured and corrected, until the uneven distribution is being reduced below a predetermined level.


Patent
MultiPhy | Date: 2016-08-16

An electro-optical FIR transmit filter comprising a segmented MZM including a plurality of MZM segments, for receiving an input optical traveling wave to be filtered; an electrical field driver, for applying a controlled electrical field required for modulation of each MZM using a control signal which controls the electrical field; delay cells associated with at least one MZM, for aligning the control signal with a travelling optical wave; and at least one electrical xT delay cell representing a filter delay, for electrically adjusting the timing of the control signal. The FIR filters coefficients are implemented in the optical domain by determining the amount of MZM segments driven by each xT delay cell, with respect to the total number of MZM segments.


A method for background calibration of sampler offsets in an Analog to Digital Converter (ADC), according to which one of the samplers of the ADC is established as a reference sampler, whose threshold and timing offsets will be the criterion for adjusting threshold offsets and timing offsets of all other samplers. Then each of the other samplers of the ADC, one at a time, is calibrated by selecting an uncalibrated sampler and establishing it as the current Sampler Under Calibration (SUC); disregarding contribution of the SUC to the output of the ADC; adjusting the threshold of the SUC to be identical to the threshold of the reference sampler; performing one-bit cross-correlation between the reference sampler and the SUC; establishing an error surface representing the threshold offset and timing offset of the SUC with respect to the reference sampler; adjusting the threshold and the timing of the SUC to be equal to the threshold and timing of the reference sampler; restoring level of the SUC to its original threshold with respect to the overall ADC and restoring contribution of the SUC to the output of the ADC.


A method for background calibration of sampler offsets in an Analog to Digital Converter (ADC), according to which one of the samplers of the ADC is established as a reference sampler, whose threshold and timing offsets will be the criterion for adjusting threshold offsets and timing offsets of all other samplers. Then each of the other samplers of the ADC, one at a time, is calibrated by selecting an uncalibrated sampler and establishing it as the current Sampler Under Calibration (SUC); disregarding contribution of the SUC to the output of the ADC; adjusting the threshold of the SUC to be identical to the threshold of the reference sampler; performing one-bit cross-correlation between the reference sampler and the SUC; establishing an error surface representing the threshold offset and timing offset of the SUC with respect to the reference sampler; adjusting the threshold and the timing of the SUC to be equal to the threshold and timing of the reference sampler; restoring level of the SUC to its original threshold with respect to the overall ADC and restoring contribution of the SUC to the output of the ADC.


An optical communication system with nonlinear equalization capability for equalizing distortions of a data communication channel, which comprises a processor for periodically gathering a predetermined number of consecutive data segments from an input data stream to a group and adding a known pilot sequence to the group, thereby forming a data frame; an optical transmitter at the input of the channel, for transmitting the data frames to a receiver, over the channel; a receiver at the output of the channel, for detecting the transmitted frames, the receiver including a demodulator. The demodulator is adapted to recover the pilot sequence of each frame; compare each recovered pilot sequence which its corresponding original transmitted pilot sequence; extract the current Channel State Information indicative of changes in the channel distortion, using the comparison results; use changes in the Channel State Information for updating the coefficients of the estimator and of the equalizer, every time a frame is received; and equalize the channel estimator and of said equalizer, every time a frame is received; and equalize the channel using the equalizer coefficients, and based on the current Channel State Information.


Patent
MultiPhy | Date: 2016-07-19

Method and system for providing seamless match point switching in an adaptive decoder (e.g., an MLSE decoder) that is based on estimation of symbol sequences, according to which statistics regarding samples corresponding to different symbol sequences in alternative match points are collected by a statistics collector, to create a set of figures of merit representing the quality of each alternative match point, while different match points are obtained by changing the delay of symbols decoded by the adaptive decoder and samples entering the statistics collector. A figure of merit of the current match point is compared to the figure of merit of alternative match points. Whenever an alternative match point figure of merit is better than the current match point by a predefined threshold, a decision to switch to the alternative match point is made. Seamless switching to the alternative match point is performed by shifting the sampling phase forward or backward, until obtaining better performance, while performing adaptation of the decoder to the sampling phase shift.


Patent
MultiPhy | Date: 2016-05-26

A driver for performing efficient low-power high-swing modulation, which comprises a first plurality of N controllable switching elements and introducing low impedance between the contacts in response to a low control level and vice versa; a second plurality of N controllable switching elements and introducing high impedance between the contacts in response to a low control level and vice versa; a DC power supply for feeding the driver, the positive port of which is connected to the common contact of the first plurality and the negative port of which is connected to the common contact of the second plurality; a plurality of N voltage dividers, each divider consisting of two serially connected resistors connecting between a free contact of a controllable switching element from the first plurality and a free contact of a controllable switching element from the second plurality, where each two controllable switching elements connected by a voltage divider forming a pair; a plurality of N control inputs, each of which jointly controlling the control inputs of a different pair; and a common output connecting between all N common points of all pairs of serially connected resistors forming the N voltage dividers.


Patent
MultiPhy | Date: 2016-05-27

A nonlinear equalizer for iteratively equalizing a data communication channel, which comprises a transmitter at the input of the channel, for transmitting data and one or more training sequences over the channel; a receiver at the output of the channel, for receiving the data and the one or more training sequences; a sampling circuit for sampling received data; a processor, for processing the samples. The processor is adapted to calculate the derivative of the MSE for each of the FFE taps; calculate the derivative of the variance of the enhanced noise with the FFE taps; iteratively update the FFE coefficients, while during each update, injecting samples of a known training sequence into the channel. During each update, the processor computes the derivative of the output noise variance, by applying convolution between the noise correlation and the current FFE taps; computes the effective channel and the modified effective channel; computes the derivative of the residual ISI, by applying correlation between the original channel h and the modified effective channel; and updates the FFE coefficients, with a step proportional to the opposite of the gradient.

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