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Modeling >> Transmission Lines and Other Distributed Devices >> "rfTlineLib/nclin" in Cadence Spectre
https://designers-guide.org/forum/YaBB.pl?num=1535622416

Message started by cheap_salary on Aug 30^th, 2018, 2:46am

Title: "rfTlineLib/nclin" in Cadence Spectre
Post by cheap_salary on Aug 30^th, 2018, 2:46am

Coupled line model is avaliable in Cadence Spectre.

Here I confirmed Coupled line model in Cadence Spectre by simple balun.

Fundamental balun operation itself is no problem.

However dependecy of substrate thickness is fairly different from Keysight ADS result.

I think Keysight ADS result is reasonable.
Here I use "MACLIN3 (Microstrip 3-Conductor Asymmetric Coupled Lines)" in Keysight ADS.

On the other hand, I use "rfTlineLib/nclin" in Cadence Spectre.

Why does "rfTlineLib/nclin" in Cadence Spectre give fairly different results ?

Code:

// Generated for: spectre
// Generated on: Aug 30 15:26:54 2018
// Design library name: My_RFDE_Test
// Design cell name: Design_of_a_Planar_Microstrip_Balun_at_S_band
// Design view name: schematic
simulator lang=spectre
global 0
parameters h=0.004 X=0.3m

// Library name: My_RFDE_Test
// Cell name: Design_of_a_Planar_Microstrip_Balun_at_S_band
// View name: schematic
stackup0 stackup names=["ground" "core" "signal" ] type=["Ref" "Diel" \ "Cond" ] thickness=[35u h 35u ] material=[stackup0_Copper \
stackup0_FR4 stackup0_Copper]
stackup0_FR4 dielectric type="const" nd=2 data=[4.3 0.018 ]
stackup0_Copper conductor type="smooth" nd=1 data=[5.813e7 ]

nclin2 (net02 0 net7 net07 net02 0 0 0) mtline stackup=stackup0 \
layer=["signal" ] len=(12.8m) linewidth=[(750u) (850u) (750u) ] \
linespace=[(X) (X) ]

nclin0 (0 net5 net8 net7 0 net5 0 0) mtline stackup=stackup0 \
layer=["signal" ] len=(12.8m) linewidth=[(750u) (850u) (750u) ] \
linespace=[(X) (X) ]

PORT1 (net8 0) port r=50 num=1 type=dc
PORT3 (net02 0) port r=50 num=3 type=dc
PORT2 (net5 0) port r=50 num=2 type=dc
simulatorOptions options psfversion="1.1.0" reltol=1e-3 vabstol=1e-6 \
iabstol=1e-12 temp=25.0 tnom=25.0 scalem=1.0 scale=1.0 gmin=1e-12 \
rforce=1 maxnotes=5 maxwarns=5 digits=5 cols=80 pivrel=1e-3 \
sensfile="../psf/sens.output" checklimitdest=psf
sp sp start=1.9G stop=3.9G step=0.01G annotate=status

Title: Re: "rfTlineLib/nclin" in Cadence Spectre
Post by cheap_salary on Aug 30^th, 2018, 2:49am

Spectre Result

Title: Re: "rfTlineLib/nclin" in Cadence Spectre
Post by cheap_salary on Aug 30^th, 2018, 2:50am

ADS Schematic

Title: Re: "rfTlineLib/nclin" in Cadence Spectre
Post by cheap_salary on Aug 30^th, 2018, 2:50am

ADS Result