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Microstrip Impedance Calculator

microstrip

Provide values for three of the four parameters H, T, W, Z0 and the relative permittivity of the dielectric. Click the button corresponding to the unknown parameter to calculate its value. ( 0.1< W/H < 3.0; 1 < εr < 15)

Select the units for all dimensions: mm mils   
(Dielectric thickness) : mm mils
(Trace thickness) : mm mils
(Trace width) : mm mils
εr (Relative permittivity) :
(Characteristic impedance): ohms
C0    (Capacitance): pF/cm pF/inch
Tpd  (Propagation delay time): 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: 0.1< W/H < 3.0; 1 < εr < 15
  • Accuracy: For typical PCB parameters (εr = 4, H = 30 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:
    0.1 < W/H < 0.2 within 5%
    0.2 < W/H < 1.5 within 2%
    1.5 < W/H < 2.0 within 5%
    2.0 < W/H < 2.7 within 10%
    2.7 < W/H < 3.0 within 15%
    C0:
    0.1 < W/H < 0.2 within 10%
    0.2 < W/H < 1.2 within 5%
    1.2 < W/H < 2.0 within 10%
    2.0 < W/H < 3.0 within 5%

Updates or corrections to this web page should be emailed to CVEL-L@clemson.edu.
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