It is fair to consider a PCB itself as a component in which multiple traces are connected. Each trace is different, some are high speed, some are low speed, some are noisy, some are used by the return path of circuit current, etc. Now, as we all know, there are lots of variations in ideal circuits and real circuits. Suppose a high-frequency trace is routed with a 7mm copper trace review film with a 0.5mm track width, it will add Inductance, Capacitance, and resistance on the track. This makes a difficult situation for high-frequency signal lines as that capacitance and inductance could change the frequency of the signal and the ending point of the trace will produce completely different results than the starting point of the trace. The major degradation of this type of signal is due to the Impedance in PCB trace. In this article, we will understand more about PCB impedance matching, and why it is important.
What is Impedance?
You can think of Impedance as resistance in AC. Impedance is also measured in Ohms, just like Resistance, but it is very different from resistance. Resistance Ohms works in DC characteristics, but the impedance is used in AC, specifically, that has a frequency.
To ensure that the signal trace is carefully designed and the quality of the signal does not degrade over the traces, impedance needs to be controlled carefully as the impedance of the traces of a PCB is generally uncontrolled.
Importance of Impedance Matching in PCB Design
Essentially, impedance control in PCB design refers to the matching of substrate material properties with trace dimensions and locations to ensure the impedance of a trace’s signal is within a certain percentage of a specific value. Controlled impedance boards provide repeatable high-frequency performance.