Crosstalk

Crosstalk is when, through cross-coupling capacitance, the signal on one net interferes with the signal on a neighbouring net. It can cause setup and hold violations and creates unwanted voltage spikes (glitches), leading to functional errors and timing deviations.

KEY Crosstalk = coupling-cap interference between nets, causing glitches and timing violations.

Avoiding Crosstalk

• Increase the spacing between nets.
• Introduce multiple vias.
• Insert buffers on the victim net.
• Use shielding.
• Increase the slew rate.
• Use a guard ring.

KEY Avoid crosstalk with spacing, multiple vias, buffers, shielding, faster slew and guard rings.

How Spacing Reduces Crosstalk

Greater spacing between two conductors effectively increases their separation, which lowers the cross-coupling capacitance between them and therefore reduces crosstalk.

KEY More spacing lowers cross-coupling capacitance, which reduces crosstalk.

Multiple Vias and Crosstalk

When several vias are used in place of one, their resistances act in parallel, lowering the overall resistance. That reduces the RC delay and, in turn, reduces crosstalk.

KEY Parallel vias cut resistance and RC delay, which reduces crosstalk.