112G PAM4 SerDes Link

Channel

Distributed loss spreads each symbol into its neighbours.

Distributed loss at 28 GHz 28 dB

VSRMRLR

Echo amplitude · +1 UI 0%

Total channel loss at 28 GHz: 28.1 dB

Crosstalk (ICN) 1.5 mV

3-tap FFE

c(−1) −0.10 · c(0) 0.75 · c(+1) −0.15

CTLE

DSP

Same CTLE & clock across DSP modes

FFE 20.8 dB FFE + DFE 21.3 dB Model · correct feedback +0.5 dB

auto: g_DC −17 dB, g_DC2 −3 dB · 12-tap FFE

RX input noise 0.8 mV

1 UI = 17.86 ps, shown as 125 ms

SNR · measured—dB

BER · observed —

Collecting samples

Before RX EQSNR — dB

After CTLE + FFESNR — dB

Eye centre · samples0 samples

Histogram = centre slice of the receiver eye. Both use the same 0 samples and amplitude scale.