Circuit Board Layout Effects

Power Line Noise

• The layout of your circuit board can result in power line noise, undesired electrical signals on the voltage and ground supply lines of your circuit. Designers prefer a constant and noise-free voltage on their power and ground lines. When noise appears on power and ground lines, the electronic circuits that receive power from these lines can become unreliable. Designers often place capacitors on power and ground lines to filter out layout induced power and ground line noise. They will also specify wider widths for the voltage and ground line traces to help eliminate the noise.

Power Consumption

• The layout of your circuit board will affect the amount of power that your electronic circuit consumes. Circuit boards that have long wires or traces will require more power than circuit boards with short wires and traces.

Signal Cross-Coupling

• The layout will affect the amount of signal cross-coupling on traces and wires that carry electrical signals. The closer two wires or traces are together, the higher the chance that the electrical signal on one trace will couple onto the adjacent trace. Traces that have high electrical signal activity will cross-couple more of their energy than those with low electrical signal activity do. Layout designers often follow strict rules that dictate the distance between two traces.

Manufacturing Yield and Reliability

• The layout will affect manufacturing yield, the number of good electronic circuits to the total number of electronic circuits produced. Poorly laid out circuits will often result in intermittent behavior of the electronic circuit. Such circuits may pass the manufacturer's tests but behave erratically when a customer uses the product.

Electrical Signal Speed

• The speed at which an electrical signal propagates through an electronic circuit is dependent on the length and the width of the wire (trace length and width) on which it must travel. As well, the number of other components that the wire is attached to will also affect the speed. The fastest electronic circuits have layouts that minimize the length and width of the wires, especially when two or more components are connected to the wire.