KEY Crosstalk is coupling-capacitance interference between nets that can cause setup or hold violations.

Avoiding Crosstalk

• Double spacing - more spacing lowers the coupling capacitance and therefore the crosstalk.
• Multiple vias - less resistance, hence lower RC delay.
• Shielding - keeps the cross-coupling capacitance constant, so crosstalk becomes a known quantity.
• Buffer insertion - boosts the strength of the victim net.

KEY Avoid crosstalk with double spacing, multiple vias, shielding and victim buffering.

How Shielding Stops Crosstalk

• Since shield lines are connected to VDD or VSS, high-frequency noise or glitches couple into VSS or VDD instead of the victim net.
• Because the shield sits at a fixed potential, the coupling capacitance stays constant.

KEY Shields tied to VDD/VSS divert glitch noise and hold the coupling capacitance constant.

Spacing and Crosstalk Noise

Greater spacing between two conductors reduces the cross-coupling capacitance between them, which in turn reduces the crosstalk.

KEY More spacing lowers coupling capacitance and therefore reduces crosstalk.

Buffering a Victim Net

A buffer increases the victim signal's strength and breaks the net into shorter segments, making the victim more tolerant of the coupled signal from the aggressor.

KEY Buffering strengthens the victim and shortens the net, improving its tolerance to aggressor coupling.