Optimal Breakout Layer Assignment for Crosstalk Mitigation - Optimal Breakout Layer Assignment for Crosstalk Mitigation - XAPP1392

PCB Channel Design Guidelines for 112 Gbps GTM Transceivers (XAPP1392)
Document ID
XAPP1392
Release Date
2023-05-23
Revision
1.0 English

The optimal breakout layer assignment for a triple-triple BGA pin pattern identified per the sweep analysis is depicted in the following figure.

  • TX port: L9 (middle column), L22, L24
  • RX port: L3, L5
Figure 1. Breakout Layer Assignment for Triple-Triple BGA Pin Pattern

The simulated worst-case RX-to-RX crosstalk profiles, including calculated power sum crosstalk from all the aggressors based on the optimal breakout layer assignment, are shown in the following table and figure.

Table 1. RX Routing
Quad Channel Routing Layer Via Length (mil)
210 RX3 L3 8.6
211 RX0 L3 8.6
RX1 L5 17.3
RX2 L3 8.6
RX3 L3 8.6
212 RX0 L5 17.3
RX1 L3 8.6
Figure 2. Simulated RX-to-RX Crosstalk Based on Optimal Breakout Layer Assignment

Similarly, the simulated worst-case TX-to-TX crosstalk profiles, including calculated power sum crosstalk from all the aggressors based on the optimal breakout layer assignment, are shown in the following table and figure.

Table 2. TX Routing
Quad Channel Routing Layer Via Length (mil)
210 TX3 L9 34.6
211 TX0 L22 102.4
TX1 L24 111.0
TX2 L9 34.6
TX3 L22 102.4
212 TX0 L24 111.0
TX1 L9 34.6
Figure 3. Simulated TX-to-TX Crosstalk Based on Optimal Breakout Layer Assignment
Note: The calculated power sum crosstalk in Figure 2 and Figure 3 includes all the adjacent aggressors, which is not the case for 112 Gbps half-density Quad.