A Maximum-Likelihood Sequence Detection Powered ADC-Based Serial Link

A 0.88 mm2 65-nm analog-to-digital converter (ADC)-based serial link transceiver is designed with a maximum-likelihood sequence detector (MLSD) for robust equalization. The MLSD is optimized in a pipelined look-ahead architecture to reach 10 Gb/s at 5.8 pJ/b and 5 Gb/s at 3.9 pJ/b, making it practical for an energy-efficient ADC-based serial link. Compared with linear equalizer and decision feedback equalizer, the MLSD provides extra margin to accommodate timing offsets, ADC nonlinearities, and voltage noise, which is exploited by co-designing the analog front-end to reduce its power and area. We present a 2x-oversampled and 2-way interleaved 5 b stochastic flash ADC architecture. No front-end analog equalizer, buffer or sample, and hold amplifier are needed. Tested with a 45-cm FR-4 trace, the serial link transceiver achieves 5 Gb/s at a bit error rate below 10−11 with a 7% UI margin without any analog front-end equalization, consuming 54.5 mW in receiver and 16.2 mW in transmitter.