According to an aspect of the present disclosure, a method comprises computing first set of coefficients of a digital filter providing first filter performance, computing a second set of coefficients from the first set of coefficients, forming a difference digital filter with second set of coefficients to produce a difference filter output and adding a compensation factor to the difference filter output to achieve a second performance identical to the first filter performance. According to another aspect, the second set of coefficients are computed as difference between the successive first set of coefficients such that when the first set of coefficients comprises N number of coefficients, the second set of coefficients comprises N1 number of coefficients. The method further comprises computing first set of coefficients according to a first relation, computing the second set of coefficients according to a second relation, generating the difference filter output in accordance with a third relation, computing a compensation factor in accordance with a fourth relation and generating a filtered output samples from a set of input samples in accordance with a fifth relation.

An information handling system may include a processing unit and a memory device. The processing unit includes a memory controller and is configured to host a BIOS. The memory device is communicatively connected to the memory controller by a communication channel and stores memory device information. The BIOS obtains the memory device information and sets an equalization of the communication channel based on the memory device information. The BIOS may further set the equalization of the communication channel based on parameters of the communication channel.

A method and system of optical communication are provided. An optical modulator device includes a first and a second waveguide segment, and is configured to modulate an incident optical signal. A first feed-forward equalization (FFE) circuit including an inner first tap and an inner second tap, is configured to equalize the first waveguide segment. A second FFE circuit including a first inner tap and a second inner tap, is configured to equalize the second waveguide segment. An FFE recombination of the first inner tap and the second inner tap of the first and second FFE circuits, is in the electrical domain, respectively. An FFE recombination of the first and second modulation signals, operative to equalize a combination of the first second waveguide segments, is in the optical domain.

An adjustable signal equalization device includes an equalizer circuitry, an analog-to-digital converter (ADC), a calculation circuitry, and a comparator circuitry. The equalizer circuitry has a transfer function, and processes an input signal based on the transfer function to generate an output signal. The ADC generates a digital signal according to the output signal. The calculation circuitry performs an accumulation according to the first digital signal to generate a first accumulated value and a second accumulated value, and generates a first detection signal and a second detection signal according to the first accumulated value and the second accumulated value. The comparator circuitry compares the first detection signal with the second detection signal to output a control signal to the equalizer circuit if the first detection signal is different from the second detection signal, in order to adjust the transfer function.

Decision feedback equalization (DFE) is used to help reduce inter-symbol interference (ISI) from a data signal received via a band-limited (or otherwise non-ideal) channel. A first PAM-4 DFE architecture has low latency from the output of the samplers to the application of the first DFE tap feedback to the input signal. This is accomplished by not decoding the sampler outputs in order to generate the feedback signal for the first DFE tap. Rather, weighted versions of the raw sampler outputs are applied directly to the input signal without further analog or digital processing. Additional PAM-4 DFE architectures use the current symbol in addition to previous symbol(s) to determine the DFE feedback signal. Another architecture transmits PAM-4 signaling using non-uniform pre-emphasis. The non-uniform pre-emphasis allows a speculative DFE receiver to resolve the transmitted PAM-4 signals with fewer comparators/samplers.

An improved receiver design implements a practical method for modeling users in SIC turbo loop multiuser detection architectures, wherein in each loop unsubtracted estimation errors from previous loops are used to appropriately scale the error covariance matrix for each user, thereby accurately representing the remaining residual interference in the data stream for each desired user. The effect of estimation errors in previous interference cancellation operations is thereby minimized, and symbol estimations in successive turbo loops are improved, for example during multiuser MMSE, multiuser MMSE with interference rejection combining (MMSE-IRC), sample matrix inversion (SMI), or any of their adaptive variants (least mean-square, recursive least square, Kalman filter etc.). The estimated residual symbol energy can be computed per symbol, and then applied to entire data streams, to groups of symbols, or to each symbol separately.

Apparatus and methods may provide improved equalizer performance, e.g., for optical-fiber-based communication systems. A least-mean-square (LMS) equalizer may include a decision feedback path containing feedback carrier recovery (FBCR), which may have low latency, and which may thus enable high-speed tap updating in the equalizer. Feed-forward carrier recovery (FFCR) may be applied, in parallel with the FBCR, to provide equalizer output by compensating, e.g., for phase noise, with improved carrier recovery/compensation, versus using FBCR to generate the output.

An improved receiver design implements a practical method for modeling users in SIC turbo loop multiuser detection architectures, wherein in each loop unsubtracted estimation errors from previous loops are used to appropriately scale the error covariance matrix for each user, thereby accurately representing the remaining residual interference in the data stream for each desired user. The effect of estimation errors in previous interference cancellation operations is thereby minimized, and symbol estimations in successive turbo loops are improved, for example during multiuser MMSE, multiuser MMSE with interference rejection combining (MMSE-IRC), sample matrix inversion (SMI), or any of their adaptive variants (least mean-square, recursive least square, Kalman filter etc.). The estimated residual symbol energy can be computed per symbol, and then applied to entire data streams, to groups of symbols, or to each symbol separately.

A feed-forward equalizer includes a shift register, a look-up table circuit, a selection circuit and an output terminal. The shift register temporarily stores and shifts input data based on a clock signal to obtain multiple shifted input data. The look-up table circuit has multiple processed signals. The processed signals are obtained by logical operation of multiple coefficients. An input terminal of the selection circuit is coupled to the look-up table circuit. A control terminal of the selection circuit receives the shifted input data. The selection circuit selects at least one of the processed signals of the look-up table circuit as a selected signal based on the shifted input data. The output terminal provides an output signal according to the selected signal.

A method for adapting a continuous time equalizer (CTE) includes determining a gain of a discrete time equalizer (DTE) and determining whether the gain has increased or decreased by more than the threshold amount. Responsive to determining that the gain has increased or decreased by more than the threshold amount, the method includes sequentially configuring the CTE for multiple CTE settings such that gain of the CTE is caused to increase or decrease in a same direction with the change in gain of the DTE. The method also includes determining a separate figure of merit (FOM) for each of the multiple CTE settings and selecting a new CTE setting from the multiple CTE settings based on the FOM for each of the multiple CTE settings.