How do you calculate impedance of a trace?
Capacitance and Impedance Intuition Impedance intuition is readily acquired through two simple equations. Trace impedance “Z” is directly related to trace inductance (L) and capacitance (C), or Z=sqrt(L/C).
What determines the characteristic impedance of a transmission line?
Characteristic impedance is determined by the geometry and materials of the transmission line and, for a uniform line, is not dependent on its length. The SI unit of characteristic impedance is the ohm. The characteristic impedance of a lossless transmission line is purely real, with no reactive component.
How to figure out the characteristic impedance of a material?
Characteristic impedance can be figured out through formula: . in which Z0 refers to the characteristic impedance; εr to dielectric constant of insulating material; h to the thickness of insulating material between traces and datum plane; w to the width of traces; t refers to the thickness of traces.
How does trace width affect the impedance of a PCB?
Based on Figure 4, it can be concluded that as trace width changes by 0.025mm, impedance will be thereafter changed by 5 to 6 ohm. In practical PCB manufacturing, however, if copper foil with width tolerance of 18μm is selected as signal plane to control impedance, the allowable trace width tolerance is ±0.015mm.
Which is more characteristic impedance stripline or microstrip?
In accordance with Figure 5 above, it is shown that microstrip structure features higher characteristic impedance than stripline structure with insulating material with the same thickness applied. As a result, microstrip structure is the preference of high-frequency and high-speed digital signal transmission.
How is the characteristic impedance of a signal plane determined?
A signal plane is set to be outer layer controlling impedance and insulating material used to separate the signal plane and its adjacent datum plane, which can be clearly seen in the image below. Characteristic impedance can be figured out through formula: .