Abstract: A system for selecting an equalizer setting of an equalizer to equalize signals received via a communications link. Starting with a first (e.g., minimum) equalizer setting and a threshold voltage near the mid-eye voltage of the equalized output signal, the system estimates the amplitude of the inner eye of the equalized output signal by comparing the equalized output signal to a series of threshold voltages. If the amplitude of the equalized output signal is less than ideal, the system dynamically increases the equalizer setting. The system quickly converges on the equalizer setting for the communication link because, rather than comparing the output signal at every voltage offset using every equalizer setting, the system only evaluates the equalizer settings necessary to select the equalizer setting for the communications link and uses only the voltage offsets necessary to evaluate each equalizer setting.

Abstract: An eye expander that increases the transmitter linearity of Pulse-Amplitude Modulation 4-Level (PAM4) signals having an inner eye and two outer eyes. In embodiments, the eye expander includes a semi-linear gain stage that increases the eye height of the outer eyes. In some of those embodiments, the semi-linear gain stage includes a semi-linear gain input transistor having a base or gate coupled to an input terminal and a collector or drain coupled to an output terminal, a semi-linear gain resistor coupled to the emitter or source of the semi-linear gain input transistor, and semi-linear gain transistor-resistor pairs that selectively connect the emitter or source of the semi-linear gain input transistor to ground. In some embodiments, the eye expander includes a limiting gain stage that reduces the eye height of the inner eye and a linear gain stage that increases the eye height of the inner and outer eyes.

Abstract: A system for selecting an equalizer setting of an equalizer to equalize signals received via a communications link. Starting with a first (e.g., minimum) equalizer setting and a threshold voltage near the mid-eye voltage of the equalized output signal, the system estimates the amplitude of the inner eye of the equalized output signal by comparing the equalized output signal to a series of threshold voltages. If the amplitude of the equalized output signal is less than ideal, the system dynamically increases the equalizer setting. The system quickly converges on the equalizer setting for the communication link because, rather than comparing the output signal at every voltage offset using every equalizer setting, the system only evaluates the equalizer settings necessary to select the equalizer setting for the communications link and uses only the voltage offsets necessary to evaluate each equalizer setting.

Abstract: A system for selecting an equalizer setting of an equalizer to equalize signals received via a communications link. Starting with a first (e.g., minimum) equalizer setting and a threshold voltage near the mid-eye voltage of the equalized output signal, the system estimates the amplitude of the inner eye of the equalized output signal by comparing the equalized output signal to a series of threshold voltages. If the amplitude of the equalized output signal is less than ideal, the system dynamically increases the equalizer setting. The system quickly converges on the equalizer setting for the communication link because, rather than comparing the output signal at every voltage offset using every equalizer setting, the system only evaluates the equalizer settings necessary to select the equalizer setting for the communications link and uses only the voltage offsets necessary to evaluate each equalizer setting.

Abstract: A system for selecting an equalizer setting of an equalizer to equalize signals received via a communications link. Starting with a first (e.g., minimum) equalizer setting and a threshold voltage near the mid-eye voltage of the equalized output signal, the system estimates the amplitude of the inner eye of the equalized output signal by comparing the equalized output signal to a series of threshold voltages. If the amplitude of the equalized output signal is less than ideal, the system dynamically increases the equalizer setting. The system quickly converges on the equalizer setting for the communication link because, rather than comparing the output signal at every voltage offset using every equalizer setting, the system only evaluates the equalizer settings necessary to select the equalizer setting for the communications link and uses only the voltage offsets necessary to evaluate each equalizer setting.

Abstract: A SerDes corn link with a retiming receiver is operable in link training (LT) mode. A SerDes transmitter includes a TX FIR channel driver to transmit TX Data with TX pre-emphasis EQ based on TX FIR coefficients. The retiming receiver includes an RTE (retimer/reclocker) with an RT FIR driver outputting retimed RX Data based on RT FIR coefficients. A link training unit (LTU) adjusts RT FIR coefficients based on a comparison of impulse cursor information for RX Data signals received at the RTE input and re-timed RX Data signals output from the RT FIR, so that the adjusted RT FIR coefficients correspond to the TX FIR coefficients (including reflecting LT changes in TX pre-emphasis EQ). In effect, the LTU performs a linear FIR coefficient translation from the TX FIR to the RT FIR, propagating LT FIR coefficient changes from RTE input to output.

Abstract: A SerDes corn link with a retiming receiver is operable in link training (LT) mode. A SerDes transmitter includes a TX FIR channel driver to transmit TX Data with TX pre-emphasis EQ based on TX FIR coefficients. The retiming receiver includes an RTE (retimer/reclocker) with an RT FIR driver outputting retimed RX Data based on RT FIR coefficients. A link training unit (LTU) adjusts RT FIR coefficients based on a comparison of impulse cursor information for RX Data signals received at the RTE input and re-timed RX Data signals output from the RT FIR, so that the adjusted RT FIR coefficients correspond to the TX FIR coefficients (including reflecting LT changes in TX pre-emphasis EQ). In effect, the LTU performs a linear FIR coefficient translation from the TX FIR to the RT FIR, propagating LT FIR coefficient changes from RTE input to output.