An On-Chip Stochastic Sigma-Tracking Eye-Opening Monitor for BER-optimal Adaptive Equalization

An on-chip stochastic sigma-tracking eye-opening monitor (SSEOM) for background adaptive equalization is presented. The proposed SSEOM detects the BER-related eye opening area accurately with a feasible degree of time/area efficiency without an external microcontroller. In addition, the SSEOM determines the BER-optimal equalization parameters for both CTLE and DFE by incorporating a pattern-dependent eye-tracking scheme. Auxiliary data samplers are employed in parallel with data samplers to track link variations and adjust the equalization parameters in the background. A 28-Gb/s CDR including a SSEOM-based adaptive equalizer is fabricated in 40nm CMOS for an evaluation.