A feed forward equalizer including a first set of filter taps having a first set of filter tap coefficients to be adapted and a second set of one or more filter taps having one or more filter tap coefficients to be constrained. The feed forward equalizer includes an adaptation component to determine a set of adapted filter tap coefficient values corresponding to the first set of filter tap coefficients and a constraint function component to determine a constrained filter tap coefficient value for the second set of the one or more filter taps having the one or more filter tap coefficients to be constrained using a constraint function based on at least a portion of the set of adapted filter tap coefficient values. The feed forward equalizer generates, based at least in part on the constrained filter tap coefficient value, an equalized signal including a set of estimated symbol values.

Provided is an equalizer including: an input amplifier configured to amplify and output an input signal; a first equalization circuit including a first sampling circuit, a first arithmetic circuit, and a second arithmetic circuit, the first sampling circuit being configured to generate and output 1-1 to 1-N feedback signals, wherein N is a natural number greater than or equal to 2; and a second equalization circuit including a second sampling circuit, a third arithmetic circuit, and a fourth arithmetic circuit, the second sampling circuit being configured to generate and output 2-1 to 2-M feedback signals, wherein M is a natural number greater than or equal to 2.

A method to implement hybrid signal processing includes steps for receiving an analog signal at a receiver frontend, sampling the received analog signal and storing the analog sampled signals using a plurality of sampling circuitries inside the receiver frontend. Then, processing the plurality of analog sampled signals using interleaved feed-forward equalizers (FFEs) to provide FFE interleaved sampled signal values corresponding to each of the sampling circuitries. Then, processing the analog sampled signals at an interleaved Decision Feedback Equalizer (DFE) to obtain DFE interleaved sampled signal values, summing each of the FFE interleaved sampled signal values with output from one of the DFE interleaved sampled signal values to provide equalizer output signal values, and digitizing the equalizer output signal values to provide digital data bits corresponding to each of the equalizer output signal values. Implementations of the method as a hybrid communication system, system-on-a-chip, and computer readable memory are also disclosed.

Techniques are described for pre-equalization at the demodulator of a satellite receiver terminal to compensate for forward link distortions. Some satellite channel filters can manifest distortions, such as asymmetric group delay response. Such distortions can conventionally force restriction of symbol rate only to the portion of the channel bandwidth having a symmetric filter response. Embodiments include a pre-equalizer in the demodulation path that filters received downlink communications based on a set of pre-equalizer filter coefficients computed to at least partially compensate for the channel filter distortions. Some embodiments support updating the filter coefficients based on channel reassignments, and/or dynamically updating the filter coefficients based on detecting and exploiting pre-equalization frames. The pre-equalized sample stream can facilitate reliable decoding by the demodulator with an appreciably increased symbol rate and correspondingly increased forward link capacity.

Embodiments provide a data sampling circuit and a data sampling device. The sampling circuit includes: a first sampling module configured to respond to a signal from a data signal terminal and a signal from a reference signal terminal and to act on a first node and a second node; a second sampling module configured to respond to a signal from the first node and a signal from the second node and to act on a third node and a fourth node; a latch module configured to input a high level signal to a first output terminal and input a low level signal to a second output terminal or input the low level signal to the first output terminal and input the high level signal to the second output terminal according to a signal from the third node and a signal from the fourth node; and a decision feedback equalization module.

Accordingly embodiments herein disclose a quarter rate speculative DFE. The quarter rate speculative DFE includes a plurality of sampler circuits connected to an input terminal. The plurality of sampler circuits are configured to sample an input signal into a plurality of data samples in parallel. A plurality of quarter rate look ahead circuit connected to the plurality of sampler circuits. The plurality of quarter rate look ahead circuit is configured to simultaneously perform an align operation and a look ahead operation on the plurality of data samples based on the different clock phases to obtain a plurality of latched outputs. A plurality of multiplexers connected to the plurality of quarter rate look ahead circuit. The plurality of multiplexers is configured to generate two speculative data streams by multiplexing respective correction coefficients of each of the plurality of latched outputs.

A feed forward equalizer including a first set of filter taps having a first set of filter tap coefficients to be adapted and a second set of one or more filter taps having one or more filter tap coefficients to be constrained. The feed forward equalizer includes an adaptation component to determine a set of adapted filter tap coefficient values corresponding to the first set of filter tap coefficients and a constraint function component to determine a constrained filter tap coefficient value for the second set of the one or more filter taps having the one or more filter tap coefficients to be constrained using a constraint function based on at least a portion of the set of adapted filter tap coefficient values. The feed forward equalizer generates, based at least in part on the constrained filter tap coefficient value, an equalized signal including a set of estimated symbol values.

A device and method for a receiver configured to perform timing recovery decoupled feed-forward equalizer (FFE) adaptation. The receiver device can include an analog front-end (AFE) device, which is coupled to a time-interleaved (TI) interface. The TI interface is coupled in a timing recovery feedback loop to FFE equalizers, a digital signal processor (DSP), a delay timing loop (DTL) device, and a clock device, which feeds back to the TI interface. The DSP has an additional pathway to the FFE equalizers, which has an additional pathway to the DTL device. The DTL loop is equipped with an interleave specific enable/disable vector Q[1:N] that can turn on/off the contribution of the specific time interleave errors to the timing recovery loop, which allows the FFE adaptation process to be decoupled from the timing recovery loop.

A slicer circuit for use in a N-tap, S-bit symbol look-ahead decision feedback equalizer (DFE) wherein the slicer comprises overflow adders and sign adders, the slicer circuit including a first processing path for generating, based on a signal sample y(n), a most significant bit (MSB) for each of 2.sup.S*N possible output symbols of the DFE, the first processing path including (2.sup.S*N)/2 overflow adder circuits, and a second processing path for generating, based on the signal sample y(n), a least significant bit (LSB) for each of the 2.sup.S*N possible output symbols, the second processing path including 2.sup.S*N sign adder circuits.

A data slicer may include an input transistor configured to generate an internal output voltage based on an input voltage at an input node. An output node may be configured to output an output voltage based on the internal output voltage, and a feedback transistor may be configured to adjust the internal output voltage based on a correction voltage corresponding to output of the output node in a previous cycle.