Microstrip differential Impedance Calculator

Microstrip are transmission lines that are routed on the external layers of the PCB which are always routed above a large reference plane on the adjacent layer. As the name suggests microstrip lines are used to convey microwave-frequency signals and RF signals. You can read more about microstrip here.

Differential impedance refers to the characteristic impedance between two lines when they are driven differentially (Like USB D+ and D-). To Calculate Input the values of characteristic impedance, trace height, and spacing between traces to obtain precise results. Understand the characteristics of your electrical transmission lines and optimize your circuit design.

Microstrip differential diagram pcbcupid

Step – 1: Calculate the Characteristic Impedance (more Info)
Trace width
Trace thickness
Dielectric thickness
Relative dielectric constant
Step – 2: Calculate the differential Impedance
Characteristic Impedance
Space Between Traces
Height of Trace


\[ d = 2 * z \left( 1 – 0.48 * e^{-0.96 * \left( \frac {s}{h} \right)} \right) \]

where :

  • d = Differential Impedance
  • z = Characteristic Impedance / Single ended Impedance
  • s = Space between traces
  • h = Height of trace

Any questions? Drop them here!