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Centered Stripline Impedance Calculator

microstrip

Provide values for three of the four parameters H, T, W, Zo and the relative permittivity of the dielectric. Click the button corresponding to the unknown parameter to calculate its value. ( W/(H-T) < 0.35; T/H <0.25; 1 < εr < 15 )


Select the units for all dimensions: mm mils
(Thickness): blank space mm mils
(Trace thickness): blank space mm mils
(Trace width): blank space mm mils
εr (Relative permittivity): blank space
(Characteristic impedance): blank space ohms
C0   (Capacitance): blank space pF/cm pF/inch
Tpd  (Propagation delay time): blank space psec/cm psec/inch

Notes

  • The formulas used here are taken from the Design Guide for Electronic Packaging Utilizing High-Speed Techniques (4th Working Draft, IPC-2251, February 2001).
    Equations from IPC-2251
  • Range of valid parameters specified in the Design Guide: W/(H-T) < 0.35; T/H <0.25; 1 < εr < 15
  • Accuracy: For typical PCB parameters (εr = 4, H = 15 mil and T = 1.37 mil), the deviation of the calculated results from results obtained using a 2D numerical field solver, is listed below:
    Z0:
    W/(H-T) < 0.05 more than 30%
    0.05 < W/(H-T) < 0.08 within 2%
    0.08 < W/H < 0.32 within 1%
    0.32 < W/(H-T) < 0.35 within 2%
    C0:
    W/(H-T) < 0.05 more than 100%
    0.05 < W/(H-T) < 0.08 within 2%
    0.08 < W/H < 0.32 within 1%
    0.32 < W/(H-T) < 0.35 within 2%