A timing recovery apparatus for signal reception in a data transmission system comprises an equalizer to equalize a received signal and a phase detector connected after the timing recovery equalizer that generates a clock tone from absolute values of the received signal after equalization.

A test device includes a comparison circuit configured to receive a plurality of input signals and generate a plurality of comparison signals based on the plurality of input signals; and a field programmable gate array (FPGA) configured to recover clock data, based on the plurality of comparison signals, wherein the FPGA includes a sampling circuit configured to generate a plurality of sample data signals by sampling the plurality of comparison signals; an edge extraction circuit configured to generate a plurality of edge data signals, based on logic values of bits in the plurality of sample data signals; an edge combining circuit configured to generate combined edge data by performing a logic operation on the plurality of edge data signals; and a filter circuit configured to recover the clock data by filtering the combined edge data.

A clock recovery circuit may include: a data slicer configured to output data values based on an input signal, a first error block, a phase adjustment loop including: a first error slicer configured to generate a first error signal based on a comparison of a threshold voltage and an input voltage, wherein the first error block is configured to selectively output the first error signal in response to a first pattern in the output data values, a second error block configured to selectively output the first error signal in response to a second pattern in the output data values, and a voltage threshold modification circuitry configured to adjust the threshold voltage based on output of the second error block, a voltage-controlled oscillator, wherein the data slicer and the first error slicer are clocked based on output of the voltage-controlled oscillator.

A clock and data recovery circuit includes a phase detector that outputs phase characteristic data based on a digital data signal and an adjustment circuit that adjusts phase characteristic data. The clock and data recovery circuit sets an adjustment value in an adjustment circuit by calculating an adjustment value of phase characteristic data using a monitor circuit while changing a phase of a reference clock signal to be adjusted in a phase interpolation circuit based on offset data output from an offset output circuit in a training period before communication starts.

System and method of timing recovery for recovering a clock signal with reduced interaction between an adaptive channel estimator and the overall timing loop for correcting clock phase. The channel response estimation in the timing recovery loop is dynamically adapted to the current channel response that varies over time. The channel estimator includes compensation logic operable to detect and compensate a correction of clock phase ascribed to the channel estimator. The compensation logic can calculate the offset between a center of filter (COF) value and a COF nominal value, the offset indicative of the amount and direction of clock phase correction contributed by the channel estimator. Based on the offset, the compensation logic adjusts the estimates channel response by adjusting the tap weights of the channel estimator to correct the offset, thereby compensating the clock phase correction.

A multi-PAM equalizer receives an input signal distorted by inter-symbol interference (ISI) and expressing a series of symbols each representing one of four pulse amplitudes to convey two binary bits of data per symbol. High-order circuitry resolves the most-significant bit (MSB) of each two-bit symbol, whereas low-order circuitry 115 resolves the immediate least-significant bit (LSB). The MSB is used without the LSB for timing recovery and to calculate tap values for both MSB and LSB evaluation.

System and method of timing recovery for recovering a clock signal by using adaptive channel response estimation. The channel response estimation in the timing recovery loop is dynamically adapted to the current channel response that varies over time. More particularly, the channel estimation coefficients used in a channel estimator can be adapted based on an error signal representing the difference between a received signal at the timing recovery loop and an estimated signal output from a channel estimator. Further, to prevent undesirable interaction between the channel estimator and the overall timing recovery loop with respect to clock phase recovery, the adaptation of channel estimation can be controlled in terms of speed or time so as to reduce or eliminate the channel estimator's effect on clock phase correction.

An input signal is sampled at a current sampling phase by a sampler device of a receiver device. The sampled input signal is equalized by an adaptive equalizer of the receiver device. One or more parameters of the adaptive equalizer are adapted, based on the equalized input signal, under one or more adaptation constraints. Phase gradient information indicative of an offset of the current sampling phase from an optimal sampling phase is determined, and the one or more adaptation constraints of the adaptive equalizer are updated based on the phase gradient information to move the current sampling phase towards the optimal sampling phase.

A clock and data recovery device includes a data sampling module, a phase detection circuit, a frequency estimator, a clock generation module, and a data recovery module. The data sampling module samples input data according to first clock signals to generate data values, in which phases of the first clock signals are different from one another. The phase detection circuit detects a phase error of the input data according to at least one second clock signal, to generate an error signal. The frequency estimator generates an adjustment signal according to the error signal, a phase threshold value, and a frequency threshold value. The clock generation module generates the first clock signals and the at least one second clock signal according to the adjustment signal and a reference clock signal. The data recovery module generates recovered data corresponding to the input data according to the data values.

A communication device includes an AFE configured to track and hold a first driving signal to produce a plurality of sample signals, a shift and hold module configured to store the plurality of sample signals, and an ADC configured to respectively convert the plurality of sample signals to a plurality of digitized sample signals, the ADC including a plurality of ADC slices. A DSP is configured to calibrate the AFE based on the plurality of ADC slices corresponding to the plurality of digitized sample signals and generate an output data stream comprising the plurality of digitized samples. A skew management module is configured to detect a skew of the plurality of digitized sample signals in the output data stream generated by the DSP module, generate a programmable skew offset based on the detected skew, and correct the skew in the output data stream based on the programmable skew offset.