The present disclosure is directed to a method and system for compensating mismatches among sub-converters in a time interleaved analog digital converter structure. A digital finite impulse response (FIR) equalization filtering unit is coupled to outputs of the sub-converters. The FIR filtering unit includes a digital FIR filter dedicated to each sub-converter. The FIR filtering coefficient is adapted specifically for each sub-converter to achieve a compensation for sub-converter mismatches and inter-symbol interference (ISI) equalization.

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 wireless communication system includes a channel estimation circuit, a shortening circuit, a time-domain decision feedback equalizer and a coefficient calculation circuit. The channel estimation circuit generates an estimated channel pulse response according to a received signal. The shortening circuit defines a shortened impulse response from the estimated channel impulse response according to a main energy distribution region of the estimated channel impulse response. The time-domain decision feedback equalizer performs time-domain equalization on the received signal, and includes a feedforward filter for filtering the received signal. The coefficient calculation circuit calculates, according to the shortened impulse response, a set of feed-forward filter coefficients to be utilized by the feedforward filter.

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.

A receiver includes a first equalizer that receives an input data signal through a communication channel and equalizes the input data signal based on a first control code to generate a first equalization signal, a second equalizer that equalizes the first equalization signal based on a clock signal and a second control code to generate a second equalization signal, a clock data recovery circuit that restores the clock signal based on the second equalization signal, deserializes the second equalization signal, and outputs a deserialized second equalization signal, and a controller that adjusts the first control code and the second control code based on the deserialized second equalization signal.

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.

Embodiments of the present disclosure provide methods and apparatus for providing feed forward equalization to a communication line by providing a resistance and a capacitance to the communication line. The method includes determining the resistance based on a desired value of feed forward equalization to provide to a communication line, determining the capacitance based on the desired value of feed forward equalization to provide to the communication line, providing a layer of resistive material between a first conductor and a second conductor of the communication line, wherein a dimension of the layer of resistive material is determined based on the determined resistance and providing a layer of dielectric material between the first conductor and the second conductor, wherein a dimension of the layer of dielectric material is determined based on the determined capacitance.

According to an embodiment, a control circuit of an equalizer configured to set a first amount to a linear equalizer, determine a second amount optimizing a non-linear equalizer with respect to a first signal generated by the linear equalizer to which the first amount is set, set the second amount to the non-linear equalizer, update an amount from the first amount to a third amount smaller than the first amount based on a magnitude of the first amount, set the third amount to the linear equalizer, determine a fourth amount optimizing the non-linear equalizer with respect to a second signal generated by the linear equalizer to which the third amount is set, and update an amount from the second amount to the fourth amount.

A comparator includes a resolver controlled by a resolver clock signal and a differential amplifier controlled by a sampling clock signal. The resolver clock signal and the sampling clock signal are such that amplification at the differential amplifier during the reset phase of the resolver clock signal and the reset phase of the sampling clock signal begins during the resolving phase of the resolver.

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.