Crosstalk delay affects timing. This occurs when both the aggressor net and the victim net are switching simultaneously or within a close timing window.
- Opposite Direction Switching: If the aggressor switches in the opposite direction to the victim (e.g., aggressor rises 0->1 while victim falls 1->0), the effect is increased delay on the victim net.
- The aggressor’s transition effectively increases the amount of charge the victim driver needs to supply/remove through the coupling capacitance (Miller effect). This makes the victim’s transition slower.
- Slower transition hurts setup timing but helps hold timing.
- Same Direction Switching: If the aggressor switches in the same direction as the victim (e.g., both rise 0->1), the effect is decreased delay on the victim net.
- The aggressor’s transition helps charge/discharge the coupling capacitance in the same direction the victim driver is trying to go, so speeding up the victim’s transition.
- Faster transition helps setup timing but hurts hold timing. This is often the worst-case scenario for hold analysis.