As mentioned in TX-to-RX Crosstalk Analysis for 56 Gbps Full-density Quad Usage, crosstalk from diagonal aggressors is more severe than that from non-diagonal aggressors. Both TX-to-TX and RX-to-RX crosstalk can be limited to one diagonal aggressor by deliberately choosing the active lanes in a Quad, thereby reducing the power sum crosstalk.
The simulated TX-to-TX and RX-to-RX crosstalk amplitudes from individual aggressors for 112 Gbps PAM4 (at 28 GHz) based on the optimal breakout layer assignment are shown in the following figure and table.
Figure 1. Simulated TX-to-TX & RX-to-RX Crosstalk Amplitudes at 28 GHz for 112
Gbps
| GM Dual Channels | Xtalk @ 112G PAM4, dB | |||
|---|---|---|---|---|
| RX-to-RX | TX-to-TX | TX-to-RX | ||
| 211_CH0 | 211_CH2 | –43.2 | –33.7 | –91.5 |
| 211_CH0 | 211_CH3 | –44.5 | –42.7 | –100.9 |
| 211_CH1 | 211_CH2 | –38.9 | –35.1 | –58.4 |
| 211_CH1 | 211_CH3 | –79.5 | –55.4 | –65.1 |