CPW Low Pass Filter Design

CPW Low Pass Filter Design using Matlab

CPW Low Pass Filter Design using Matlab
IEEE paper used: 0-7803-7070-8/2001
Topic:CAD Formulas and Their inverse for microstrip,CPW and conductor backed CPW By Successive Synthetic Asymptotes
Authors:Wan C. Tang & Y.Leonard Chow (City univ of Hong-Kong)

Cpw low pass filter is designed using cad formulae obtained by Successive Synthetic Asymptotes .
Synthetic Asymptote is a powerful technique in deriving simple CAD formulae.
Chebychev or Butterworth LP Filter is designed using filter design concepts .
Then CAD Formulae are used to design the corresponding cpw

Formulae used for filter design :

Chebychev Filter
g0=1
g1=2a1/γ
gk=4ak-1ak/(bk-1*gk-1) k=2,3â?¦.n
gn+1=1 n-odd
gn+1=coth2β/4 n-even
ak=sin((2k-1)Ï?/2n) k=1,2,â?¦n
bk=γ2+sin2(kÏ?/n)
β=ln(coth(Am/17.37))
γ=sinh(β/2n)
A=10log[1+(10Am/10-1)cos2(ncos-1wâ??)]

Butterworth Filter
A=10log[1+wâ??2n]
g0=1
gk=2sin((2k-1)Ï?/2n) k=1,2,â?¦n
gn+1=1
where
n-orderof filter
Am-Ripple magnitude in dB
wâ??-Bandwidth over which the insertion loss has the maximum ripple Am.
A-Attenuation

Frequency and Impedance Scaling
gr-resistance
gl-Inductance
gc-Capacitance

New Prototype values
R=RogR L=RogL/w C=gC/wRo

CPW Realisation

Lengths
jLw=jZohsinβl
1/jCw=Zol/jsinβl

Widths
Formula is got from IEEE paper
One of the 2 parameters are assumed (b in this case) and the corresponding value for other parameter(a in this case) is obtained
Submitted By:
Miriyala Aravind
Bihani Tushar Jawaharlal