Cross coupling between power and signal traces on printed circuit boards

Switching power supplies and other power switching circuits produce high frequency components in currents on power traces and power grounds in printed circuit boards (PCBs). These time-varying currents can couple energy (noise) to low level signal traces such as those normally encountered with the new low voltage high speed logic families and microprocessors. This can cause the system to malfunction or result in EMI emissions that exceed the levels allowed by regulatory agencies. The effect of proximity and position of power switching circuits with respect to the signal traces is examined.