Gain and equalization adaptation to optimize the vertical eye opening in a wireline receiver

A strategy for the adaptation of an equalizer and variable gain amplifier is presented. Both control signals are generated by examining the probability density function (PDF) of the received data, which is obtained from the DC output of an additional analog sampler at the equalizer output. This technique works to minimize the spreading of the PDF of the received signal while adding only minimal complexity and power consumption to the receiver design. The technique is demonstrated in a wireline receiver fabricated in 65-nm CMOS technology. Measured results show that the adaptation scheme functions correctly over both coax and PCB channels of varying lengths and at speeds ranging from 2 to 10 Gb/s.