Import an ADS-Layout into CST MICROWAVE STUDIO
CST MICROWAVE STUDIO manages an ADS® Design Kit which contains a dynamically extended list of EM simulation components (CST MICROWAVE STUDIO projects or S-Parameter data files). The difference between the levels of integration is how simulation results are handled for a particular component.
The integration supports changing parameters of the 3D EM models directly from within the ADS® environment.
The ”static” link (ADS® 2003A and above) requires parametric CST MICROWAVE STUDIO results to be computed before the component is used within ADS®. The results are written into a local database which is then interpreted by the component. The circuit simulator automatically interpolates the S-parameter between the pre-computed samples. The static link can be used for structures with up to 6 ports.
Moreover, the ”co-simulation” alternative enables ADS® to launch CST MICROWAVE STUDIO in order to automatically calculate required data. All information is stored together with the CST MICROWAVE STUDIO model to avoid unnecessary repetitions of lengthy EM simulations. The co-simulation interface requires ADS® 2005A or above.
Since the Design Kit is required for the static link as well as the dynamic link the following steps are needed for both links:
Open the "Install
ADS Design Kit" in ADS®
Select Design Kit 
Install Design
Kits from the ADS® main menu to open the following dialog box:
Specify the Location of the Design Kit
Clicking the Browse button next
to the Path entry allows to specify
the path to the Design Kit which is located in a subfolder of the CST
STUDIO SUITE library folder.
By default, the library is located in a subfolder
of the CST STUDIO SUITE installation directory.
If [install_path] is the installation directory, the Design Kit is
stored at the following location:
[install_path]\Library\ADS\CST_ADS_DK_1
If you have the default configuration choose this folder as the Design
Kit’s path. Once the path is set properly, the remaining fields
in the dialog box will be filled in automatically as shown in the picture
above.
Click the OK button to activate the changes
Refer to the ADS® documentation for more information on managing Design Kits.
The static link can be used right after installing the Design Kit. The static link can be used for structures with up to 6 ports.
In the following, we explain how to add the results of an CST MICROWAVE STUDIO project as a component to the ADS® Design Kit.
Open the CST MICROWAVE STUDIO project of which you want to use the results for the static link
Add
a 1D result template named ADS
Component Export.
Now all parametric S-parameters which are computed after adding the
template will be stored in a local database. Please note that performing
model changes other than simple parametric changes will automatically
delete this database.
Once the result template is defined, you can run simulations for various
parameter settings. All entries in the S-parameter database will then
become available for use within ADS®.
Note: If you already have S-parameter data available before adding
the result template, you can click the Evaluate
button in the template based post-processing dialog box in order to add
the existing S-parameters to the data set right away. However, only the
latest S-parameter results will be added.
Open
the Export
Agilent ADS Component
dialog
Choose Post Processing:
Exchange Import/Export 
Export ADS
Component:
The parameter list shows all parameters that have been varied in the
currently available database. Please note that parameters depending on
other parameters in form of expressions are not listed here. (See also
Export
Agilent ADS Component )
Assign
a Type to every Parameter
Each parameter needs to have a Type assigned to it in order
to properly handle potentially different unit settings in CST MICROWAVE
STUDIO and ADS®. Make sure to specify the correct type according to the
physical meaning of the parameter. In the example shown above, the type
Length should be chosen
for the parameter ”radius”
Enter
a proper Component Description
And double-check the types for every parameter.
Click
OK to create the component
Now the currently available S-parameter data will be copied to the
Design Kit.
Note: Subsequently performed S-parameter simulations will not automatically
add new data to the Design Kit.
Restart
ADS
If ADS® is running it is necessary to restart
ADS®. Otherwise it will not note the changes in
the Design Kit. The component can then be accessed
from the ADS® library browser by selecting Insert
Component Component
Library.
A powerful feature of the co-simulation link is the ability to automatically launch CST MICROWAVE STUDIO from within ADS® if new S-parameter data are requested. This interface requires ADS® 2005A or above and needs CST MICROWAVE STUDIO and ADS® to be installed on the same computer.
Do the following steps to setup a Co-Simulation:
Preparations in CST MICROWAVE STUDIO
Open the CST MICROWAVE STUDIO project to be used for the dynamic link
Open the Co-Simulation dialog box
Choose Post Processing:
Exchange Import/Export Setup ADS Co-Simulation:
Activate
Enable ADS Co-Simulation
You can also specify a Description
text which will later be shown in the ADS® library browser.
Define the Solver type
This setting specifies which solver (transient or frequency domain)
will then be used for the calculation.
Define the parameters that will
be accessible from within ADS®
The parameter list shows currently defined parameters that can be used
for the co-simulation. If a parameter depends on another parameter (e.g.
in form of an expression), its value cannot be set directly. Therefore,
dependent parameters are not shown in this list. A parameter can be controlled
from within ADS® if its Use option
is checked. This selection allows you to hide parameters from being visible
in the ADS® component options.
Use Interpolation
The Use interpolation option specifies
whether S-parameter data may be interpolated or not. If this option is
switched off, the S-parameters will be directly calculated for every requested
parameter combination. If the interpolation feature is activated, the
interpolation is done on a regular grid of anchor points. The grid is
determined by the Nominal Value and
Step Size settings which can be independently
specified for each parameter.
The following picture illustrates how the interpolation scheme works
for the simplest case of one parameter:
CST MICROWAVE STUDIO simulations are only carried out at the uniformly
spaced anchor points of the interpolation grid. The grid’s origin
is specified by the Nominal value
whereas the Step Size determines the
distance between two consecutive anchor points.
Whenever a new data point is requested, the two closest neighboring
anchor points are determined and their contributions to the requested
sample are calculated. Based on the corresponding anchor point’s
S-parameter data and these interpolation weights, the requested S-parameters
can then be obtained by linear interpolation. This scheme can be straightforwardly
extended to handle multiple parameters as well.
In the dialog box, you can specify each parameter’s interpolation
options by directly editing the values in the parameter list. Please note
that these settings will only be used when the interpolation option is
switched on.
Click OK to create the Design Kit
component
Clicking the OK button finally
creates or updates the Design Kit component.
Note: Make sure to restart ADS®
in order to update these changes.
Preparations in Agilent ADS
Copy
the Component .dll int the ADS instalation directory
Depending on the ADS version you have, different files need to be copied
from the
"[CST STUDIO SUITE_Install_Path]\Agilent
ADS Plugin" or "[CST
STUDIO SUITE_Install_Path]\Agilent
ADS Plugin (64 Bit)"
directory into the
"[ADS_Install_Path]\bin"
or "[ADS_Install_Path]\bin\win32_64"
directory.
Please refer to the "Readme.txt" file in [CST STUDIO
SUITE_Install_Path]\Agilent
ADS Plugin" or [CST STUDIO SUITE_Install_Path]\Agilent ADS Plugin (64 Bit)" folder for a detailed description.
Start
ADS and open the "Component Library"
The components can now be accessed from the ADS® library browser: Select
Inser
Component Component Library.
Insert the desired component from the library browser into the ADS® schematic by "drag and drop"
Final Remarks
The following picture shows a co-simulation component after it has been placed on the ADS® schematic:
The component’s options allow changing the interpolation type (1=yes, 0=no) and CST MICROWAVE STUDIO model parameters directly from within the ADS® environment. Furthermore the component displays information about the frequency range of the EM simulation.
The Design Kit component is now dynamically linked to the CST MICROWAVE STUDIO model. Whenever new S-parameter data for a particular parameter combination are computed, these data will become available to ADS® right away.
Note 1: Whenever a parametric model is used for ADS® co-simulation, it is advisable to test whether the structure update succeeds for various parameter combinations before creating the ADS® Design Kit component.
Note 2: If you are using CST MICROWAVE STUDIO version 2008 and later and if you want to use the components created by CST MICROWAVE STUDIO version 2006b or prior, special care needs to be taken. Please read "ADS Design Kit Compatibility Issues" for further information.
Note 3: The ADS Component Export 1D result template stores the S-parameter information in the Result folder in an MDIF file with the extension mdf.
Besides exchanging S-Parameter data there is also a possibility to exchange structure information between ADS® and CST MICROWAVE STUDIO.
To create a layout that can be imported by CST MICROWAVE STUDIO do the following:
Preparations in ADS
Enter the Layout View in ADS
Select
Momentum 3D
EM Save
files for 3D EM
All necessary files will be written. A message box will tell you where
the files can be found.
Preparations in CST MICROWAVE STUDIO
Select
Modeling:
Exchange Import/Export 3D Files ADS Model.
Select the appropriate project in the file selector box
Choose the right import options.
Press OK to confirm
the setting
The ADS layout will now be imported into CST MICROWAVE
STUDIO including definition of materials, layers, ports etc.
ADS Design Kit Compatibility Issues, ADS Co-Simulation, Export Agilent ADS Component, ADS import options