Dual Stripline Impedance Calculator

Cross-sectional diagram of a dual-strip structure with dimensions labeled: width (W), height (H), conductor thickness (T), and spacing (C).

Provide values for four of the five parameters H, C, 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/Hr < 15 )

Select the units for all dimensions: mm mils

H (Thickness):   mm mils
C (Separation) :   mm mils
T (Trace thickness):   mm mils
W (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).
Dual Formula
 
  • Range of valid parameters specified in the Design Guide: W/(H-T) < 0.35; T/H r < 15;
  • Accuracy: For typical PCB parameters (εr = 4, H = 15 mil, C = 10 mil and T = 1.37mil), the deviation of the calculated results from results obtained using XFX, a 2D numerical field solver from Innoveda, is listed below:
Zo:  
W/(H-T) < 0.04 more than 30%
0.04 < W/(H-T) < 0.08 within 5%
0.08 < W/H < 0.35 within 1%
Co:  
W/(H-T) < 0.04 more than 80%
0.04 < W/(H-T) < 0.08 within 5%
0.08 < W/H < 0.27 within 10%
0.27 < W/H < 0.35 within 12%