A 4.8pJ/b 56Gb/s ADC-Based PAM-4 Wireline Receiver Data-Path with Cyclic Prefix in 14nm FinFET

This work presents an ADC-based receiver (RX) data-path for frame-based PAM-4 modulation with a cyclic prefix (CP). Similar to discrete multi-tone (DMT) modulation, a frame of PAM-4 symbols are protected from the channel delay spread by the CP taps. A PAM-4 frame window including CP taps is viewed as a DMT symbol and is equalized similarly to a DMT signal equalization, based on a discrete-time Fourier transform (DFT) and frequency-domain equalizer (FDE). The RX prototype implemented in 14nm FinFET achieves 56Gb/s data-rate at less than 3e-5 pre-FEC BER over a 19dB loss channel at 14GHz dissipating 270mW including the ADC and the DSP data-path excluding the inverse DFT and the BER checker.