US Patent 10250417 Serial link adaptive equalization using track and hold circuits

One feature pertains to an apparatus that includes a first stage track and hold circuit that subsamples a receive equalizer output of a receive equalizer, and a second stage track and hold circuit that generates a first signal representative of an average voltage value of a logical value at the receive equalizer output when a high frequency bit pattern is detected, and a second signal representative of an average voltage value of the logical value at the receive equalizer output when a steady state bit pattern is detected. The apparatus further includes a comparator circuit that generates a comparator output signal that indicates which of the first signal and the second signal has a greater magnitude, and a processing circuit that generates equalizer tuning signals based on the comparator output signal to adjust parameters of an equalizer that affects the receive equalizer output.