Cross Talk

Cross Talk Delay Effects
Delta Delay and Fanout Stage Effect
Crosstalk Noise Effects

Aggressor and Victim Nets

Signal integrity is the ability of an electrical signal to carry information reliably and resist the effects of high-frequencyelectromagnetic interference from nearby signals.

Crosstalk is the undesirable electrical interaction between two or more physically adjacent nets due to capacitive cross-coupling. As integrated circuit technologies advance toward smaller geometries, crosstalk effects become increasingly important compared to cell delays and net delays.

Cross talk noise effects:

A signal should be constant for some time. But during the transition in adjacent signal causes anoise bump / glitch on constant signal.

If the glitch is significantly high , it can cause incorrect logic to be propagated.

Noise Bump Due to Crosstalk

Aggressor and Victim Nets:

Victim: A net which receives undesirable signal due to near by net called victim.

Aggressor: A net which causes these undesirable signals on victim net is known as Aggressor.

Note that an aggressor net can itself be a victim net; and a victim net can also be an aggressor net. The terms aggressor and victim refer to the relationship between two nets being analyzed.

The timing impact of an aggressor net on a victim net depends on several factors:

• The amount of cross-coupled capacitance
• The relative times and slew rates of the signal transitions
• The switching directions (rising, falling)
• The combination of effects from multiple aggressor nets on a single victim net

Effects of Crosstalk at Different Arrival Times

As shown in Figure, if the transition on A occurs at about the same time as the transition on B, it could cause the transition on B to occur later, possibly contributing to a setup violation; otherwise, it could cause the transition to occur earlier, possibly contributing to a hold violation.

If the transition on A occurs at an early time, it induces an upward bump or glitch on net B before the transition on B, which has no effect on the timing of signal B. However, a sufficiently large bump can cause unintended current flow by forward-biasing pass transistor. Prime Time SI reports the worst-case occurrences of noise bumps.

Similarly, if the transition on A occurs at a late time, it induces a bump on B after the transition on B, also with no effect on the timing of signal B. However, a sufficiently large bump can cause a change in the logic value of the net, which can be propagated down the timing path. Prime Time SI reports occurrences of bumps that cause incorrect logic values to be propagated.

Reference:

https://solvnet.synopsys.com/dow_retrieve/I-2013.12/ptug/signal_integrity.html?otSearchResultSrc=advSearch&otSearchResultNumber=1&otPageNum=1#BABHDCFI