tutorial simulation of a coupler circuit with z and ... -.pdftutorial simulation of a coupler...
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Tutorial Simulation of a coupler circuit with
Momentum and EMDS simulations tools.
Objective of this tutorial is to show how use
ADS and the electromagnetic simulators to
simulate a coupler circuit at 1.5GHz centre
bandwidth frequency.
For the design of couplers circuit there are a
lot of references in literature [1-3]. The
general structure of a circular coupler it
consist in realize a square structures formed
by λ/4 sides of same and different width.
Create a new project with ADS and save them
as coupler. Create a new schematic and save
with name. By the t-lines microstrip palette
choose the substrate modeller and put them in
the schematic. Save the substrate as FR-4.
Figure 1
Now you can use linecalc tool to compute the
lengths and width for your circuit.
Then press tools and start linecalc. In this tool
you can define the same parameters of
substrate and save them.
Figure 2
After the modelled was done you can insert
the desired value of characteristic impedance
Z0 and electric equivalent wavelength E-Eff
then press the button sinthesize and width and
length are calculate automatically. Repeat the
design steps with linecalc but in order to
generate a transmission line with
characteristic impedance of
Ω≈= 35.352
50
2
0Z
Figure 3
Now you can generate the layout and work at
layout system to achieve the complete design.
Press Layout then generate update and click
on ok, the following window appears.
Figure 4
Now you can add, remove or modify
components to achieve the circuit.
Add the MTE component to match and
complete the design selecting for terminals
one and three the same dimensions of the line
parts. At the end you can click on schematic
to update the schematic from layout and
verify the connections. After you can add the
ports by schematic and recreate the layout.
These design steps are showed in the figures
below:
2
Figure 5
Figure 6
CoupledIsolated
DirectInput
MLINTL5
L=10 mmW=2.98 mm
Subst="MSub1"
PortP3Num=3
PortP1Num=1
PortP2Num=2
PortP4Num=4
MLINTL6
L=10 mmW=2.98 mm
Subst="MSub1"
MLINTL8
L=10 mmW=2.98 mm
Subst="MSub1"
MLIN
TL4
L=26.37 mmW=5.12 mm
Subst="MSub1"
MLINTL3
L=27 mmW=2.98 mm
Subst="MSub1"
MTEE_ADS
Tee1
W3=2.98 mm
W2=2.98 mm
W1=5.12 mmSubst="MSub1"
MLINTL2
L=26.37 mmW=5.12 mm
Subst="MSub1"
MLINTL7
L=10 mmW=2.98 mm
Subst="MSub1"
MTEE_ADSTee3
W3=2.98 mmW2=2.98 mmW1=5.12 mm
Subst="MSub1"
MLINTL1
L=27 mmW=2.98 mm
Subst="MSub1"
MTEE_ADS
Tee2
W3=2.98 mm
W2=2.98 mm
W1=5.12 mmSubst="MSub1"
MSUBMSub1
Rough=0 mm
TanD=0.025T=17 umHu=1.0e+033 mm
Cond=1.0E+50Mur=1Er=4.5
H=1.6 mm
MSub
MTEE_ADSTee4
W3=2.98 mmW2=2.98 mmW1=5.12 mm
Subst="MSub1"
Figure 7
Then the last figure that show the layout view
obtained by the schematic
Figure 8
For simulations you can at first verify the S-
parameters simulation or put a kind of time
source at the input port and see how the signal
behaves at others ports.
To simulate the circuit for example by using
momentum you must import the substrate
from the schematic as show in the figure
below
Figure 9
You can also to save the data for the 3D view.
And click on simulation voice of the menu to
define the simulation parameters. At least
click on simulate
Figure 10
After the simulation you can visualize the
results and compare to of s parameters
simulations.
3
1.35 1.40 1.45 1.50 1.55 1.60 1.651.30 1.70
60
80
100
120
140
40
160
Frequency
Phase [deg]
S11
freq (1.300GHz to 1.700GHz)
S11
Wed Jul 23 2008 - Dataset: coupler_mom_a
1.35 1.40 1.45 1.50 1.55 1.60 1.651.30 1.70
-25
-20
-15
-10
-30
-5
Frequency
Mag. [dB]
S11
Figure 11
The red line is the trade of S11 parameterized
in frequency of S-parameters simulations
whereas the blue line represent the results of
Momentum simulation. The results can be
visualized using the post processing
visualization by means of which it is possible
to simulate the current view for all ports
Figure 12
Figure 13
At least we will use EMDS to achieve a 3D
electromagnetic simulation of the circuit. To
simulate the circuit by using the EMDS you
can repeat the lasts two steps executed for
momentum, in others words to import the
substrate and simulate with S parameters.
After launch the simulation a windows like
this appears in your workspace, that allows
you to control the proceed of the simulation.
Figure 14
By using the same post-processing
visualization tool it is possible to plot all field
configuration and animate them to see how
work the designed device. IN the following
figure we plot for example the Electric field
and the Electric far field.
Figure 15
4
Figure 16
REFERENCES
[1] David. M. Pozar “Microwave Engineering”, AddisonWesley
Massachusset 1990.
[2] Robert E. Collin, “Foundations For Microwave Engineering”,
McGraw-Hill International editions, 1992.
[3] I.D.Robertson, S. Lucyszyn “RFIC and MMIC design and
technology”, Inatitute of Electrical Engineers, 1991.