Consider two differential pairs routed on the same signal layer as shown in Figure 1 with a height (H) from the reference plane.
Table 6. Microstrip NEXT vs. Aggressor Separation Microstrip routing requires a separation of 6H and 7H to properly manage the crosstalk coupling to less than 1% for NEXT and FEXT, respectively. However, to achieve 1% of crosstalk coupling using stripline routing, requires only 5H separation for NEXT and 2H separation for FEXT.
| Separation (D) |
Isolation (dB) |
Coupled Voltage from a 1-V Aggressor (mV) |
Coupling (%) |
| 1H |
22 |
79 |
7.9 |
| 2H |
27 |
45 |
4.5 |
| 3H |
31 |
28 |
2.8 |
| 4H |
35 |
18 |
1.8 |
| 5H |
36 |
16 |
1.6 |
| 6H |
41 |
9 |
0.09 |
Table 7. Microstrip FEXT vs. Aggressor Separation Microstrip routing requires a separation of 6H and 7H to properly manage the crosstalk coupling to less than 1% for NEXT and FEXT, respectively. However, to achieve 1% of crosstalk coupling using stripline routing, requires only 5H separation for NEXT and 2H separation for FEXT.
| Separation (D) |
Isolation (dB) |
Coupled Voltage from a 1-V Aggressor (mV) |
Coupling (%) |
| 6H |
34 |
20 |
2.0 |
| 7H |
41 |
9 |
0.09 |
Table 8. Stripline NEXT vs. Aggressor Separation
| Separation (D) |
Isolation (dB) |
Coupled Voltage from a 1-V Aggressor (mV) |
Coupling (%) |
| 1H |
24 |
63 |
6.3 |
| 2H |
32 |
25 |
2.5 |
| 3H |
36 |
16 |
1.5 |
| 4H |
39 |
11 |
1.1 |
| 5H |
40 |
10 |
1.0 |
Table 9. Stripline FEXT vs. Aggressor Separation
| Separation (D) |
Isolation (dB) |
Coupled Voltage from a 1-V Aggressor (mV) |
Coupling (%) |
| 1H |
32 |
25 |
2.5 |
| 2H |
40 |
10 |
1.0 |
Note: Use stripline routing to avoid FEXT concerns. Use stripline traces with 5H differential pair-to-pair separation to minimize NEXT to 1%.
Note: If microstrip routing is required, used 6H-7H differential pair-to-pair separation to avoid NEXT and FEXT issues.