Mex-Wcalc: coplanar

Mex-Wcalc: coplanar_calc

coplanar_calc - Symmetric coplanar transmission line analysis

SYNOPSIS

[z0, keff, elen, loss, L, R, C, G, lc, ld, deltal, depth] = coplanar_calc(w, s, h, l, tmet, rho, rough, er, tand, with_ground, f)

PARAMETERS

INPUT PARAMETERS

w : width of coplanar line (meters)
s : space between line the the coplanar ground (meters)
h : substrate thickness (meters)
l : lentgh of coplanar line (meters)
tmet : metal thickness (meters)
rho : resistivity of the line (relative to copper)
rough : conductor surface roughness (meters-rms)
er : substrate relative permitivitty
tand : substrate loss tangent
with_ground : 0 for no bottom side ground, 1 for bottom side ground plane
f : analysis frequency (Hz)

OUTPUT VALUES

z0 : calculated characteristic impedance (Ohms)
keff : calculated effective relative permitivity
elen : calculated electrical length of the line (degrees)
loss : calculated loss of the line (dB)
L : calculated inductance per length (Henries/meter)
R : calculated resistance per length (Ohms/meter)
C : calculated capacitance per length (Farads/meter)
G : calculated conductance per length (Siemens/meter)
lc : conductor loss (dB/meter)
ld : dielectric loss (dB/meter)
deltal : calculated open circuit end correction (meters)
depth : calculated skin depth (meters)

DESCRIPTION

Function to analyze the electrical characteristics of a single coplanar transmission line. The physical dimensions of the coplanar line are given as inputs and the characteristic impedance, effective dielectric constant, loss and open circuit end correction are calculated. The model accounts for dispersion (frequency dependent propagation velocity).


           |<--S-->|<--W-->|<--S-->|
     ______         _______         ______ 
    )      |       | metal |       |      ( <- rho,rough
    ----------------------------------------------
   (  dielectric                         /|\     (
    )   er,tand                       H   |       )
   (                                     \|/     (
    ----------------------------------------------
    XXXXXXXXXXXXXXXXXX ground XXXXXXXXXXXXXXXXXXXX

EXAMPLE

 % mils to meters conversion factor
sf=25.4e-6;
 % width
w=20*sf;
 % space
s=20*sf;
 % height
h=15*sf;
 % length
l=1100*sf;
 % metal thickness
tmet=1.4*sf;
 % resitivity
rho=1.72e-8;
 % metal surface roughness
rough=0.05*sf;
 % relative dielectric constant
er=4.5;
 % loss tangent
tand=0.01;
 % frequency
f=2.4e9;
[z0,keff,elen,loss,L,R,C,G,lc,ld,deltal,depth] = ...
  coplanar_calc(w,s,h,l,tmet,rho,rough,er,tand,0,f);
disp(sprintf('z0   = %8.4g Ohms', z0));
disp(sprintf('keff = %8.4g ', keff));
disp(sprintf('elen = %8.4g degrees', elen));
disp(sprintf('loss = %8.4g dB', loss));
disp(sprintf('L    = %8.4g H/m', L));
disp(sprintf('R    = %8.4g Ohms/m', R));
disp(sprintf('C    = %8.4g F/m', C));
disp(sprintf('G    = %8.4g S/m', G));
disp(sprintf('lc   = %8.4g dB/m', lc));
disp(sprintf('ld   = %8.4g dB/m', ld));
disp(sprintf('open end correction = %8.4g mil', deltal/sf));
disp(sprintf('skin depth = %8.4g um', depth*1e6));