Using the GENESYS Synthesis/SPECTRASYS link from ADS

This chapter details how to use the GENESYS Synthesis/SPECTRASYS link from ADS.

GENESYS Synthesis/SPECTRASYS Design Flow

The following illustration shows the flow of engineering tasks and how GENESYS Synthesis, SPECTRASYS, and ADS take part.

How the GENESYS Synthesis/SPECTRASYS link works

The link between ADS and GENESYS Synthesis/SPECTRASYS allows you to transfer GENESYS schematics to ADS. It is available only from Windows installations. GENESYS is not available in UNIX. The link transfers only schematics and linear simulations. It does not transfer layouts, plots, or datasets.

To transfer a schematic from GENESYS to ADS, both GENESYS and ADS must be running. In GENESYS, the Workspace that contains the schematic must be open. In ADS, the project to which the schematic will be transferred must be open.

Note

The link transfers schematics only from GENESYS to ADS. It does not transfer schematics from ADS to GENESYS.

Establishing the link

To establish a link between ADS and GENESYS, you can Launch GENESYS from ADS. This automatically establishes a link between the current ADS project and the GENESYS Workspace. Select the File > Export > Export Schematic to ADS command in GENESYS. See Transferring schematics from GENESYS to ADS for more information.

Breaking the link

The run-time link connects an open ADS project and an open GENESYS Workspace.

The link is broken when: You close the current project in ADS, by either closing the project itself or exiting ADS. You close the current Workspace in GENESYS, by either closing the Workspace itself or by exiting GENESYS.

Folders used by the GENESYS Synthesis/SPECTRASYS link

The ADS project folder

When you launch GENESYS from ADS, the default folder for saving the GENESYS workspace is in the ADS project. The advantage of this is that when you archive the ADS project, the GENESYS workspace get included in the archive.
The workspace for synthesis is saved in the folder

MyProject_prj\workspaces\synthesis

The workspace for SPECTRASYS is saved in the folder

MyProject_prj\workspaces\spectrasys

If these folders do not exist, ADS creates them as needed.

The Temp directory

When exporting schematics to ADS, GENESYS creates two files. Transfer.iff is the IFF file that is used to transfer the schematics from GENESYS to ADS. Transfer.log is a log file that contains messages generated during the export.

These files are located in the Temp folder that is based on your Windows user name:

C:\Documents and Settings\userName\Local Settings\Temp

Where userName is your Windows user name.

Component Mappings

An instance on a GENESYS schematic has two important pieces of information, the model and the symbol. The Model determines what parameters the instance has and how the instance is simulated. An instance that uses the RES model has one parameter, named R, and simulates as a two-terminal ideal resistor. An instance that uses an IND model has one parameter, named L, and simulates as a two-terminal ideal inductor. The Symbol determines how the instance is drawn on the schematic. An instance that has the RESISTOR symbol is drawn as a two-terminal resistor. An instance with the INDUCTOR symbol is drawn as a two-terminal inductor.

After you insert an instance on a GENESYS schematic, you can change its symbol without changing its model. This is quite different from ADS. In ADS, a component has a fixed simulation model and a fixed symbol. When you insert an instance of a component in ADS, you cannot change its symbol.

When GENESYS transfers an instance to ADS, GENESYS looks for the component mapping that corresponds to the model/symbol pair of the GENESYS instance. That mapping, if it exists, tells GENESYS which ADS component to use. It also tells GENESYS how to map the GENESYS model parameters to the ADS component parameters.

Example 1:

A GENESYS instance for a resistor has Model=RES and Symbol=RESISTOR. The parameter R is set to 50. This is a standard model/symbol pair and the component mapping exists. The mapping, see RES (Ideal Resistor), indicates that the corresponding ADS component is R. It also specifies that the R parameter of the GENESYS RES model corresponds directly to the R parameter of the ADS R component. GENESYS transfers the instance as an instance of the R ADS component. It sets the value of the ADS instance's R parameter to 50.

A GENESYS instance can use a user-defined symbol that the mapping rules know nothing about. Or the GENESYS instance can use a non-standard symbol (such as using the INDUCTOR symbol with the RES model). To map this instance to an ADS component, an intermediate subcircuit is used.

Intermediate Subcircuit

When GENESYS finds a component mapping that matches the GENESYS model but cannot find a component mapping that matches both the GENESYS model and symbol, GENESYS creates a new ADS subcircuit. We call this an intermediate subcircuit. Its sole purpose is to provide a new symbol for an ADS component.

You can recognize an intermediate subcircuit by its component name. It always starts with genesyslib .

The symbol for the intermediate subcircuit is a copy of the GENESYS symbol. The schematic for the subcircuit contains exactly one instance. It's an instance of the ADS component that corresponds to the GENESYS model. The name of the intermediate subcircuit is genesyslib<MODEL><SYMBOL>, where MODEL is replaced by the GENESYS model name and SYMBOL is replaced by the GENESYS symbol name. The parameters of the intermediate subcircuit are the same as the parameters of the GENESYS model. The parameters of the ADS instance inside the subcircuit are set to the corresponding parameters of the subcircuit.

Example 2:

A GENESYS instance for a resistor has Model=RES and Symbol=MyResistor where MyResistor is a user-defined symbol. The parameter R is set to 50. This is not a standard model/symbol pair and no mapping exists that matches both the model and the symbol. But a mapping is found that matches the model. (This is the same mapping found in example 1.) The mapping indicates that the ADS R component corresponds to the RES model, see RES (Ideal Resistor). It also specifies that the R parameter of the GENESYS RES model corresponds directly to the R parameter of the ADS R component. GENESYS creates a two-terminal ADS subcircuit called genesyslib_RES_MyResistor. The symbol for this ADS subcircuit is a copy of the MyResistor symbol. The schematic for this subcircuit is an instance of an R component with each pin connected to a port of the subcircuit. The subcircuit has one parameter R. The R parameter of the ADS R component inside the subcircuit is set to R. You can see that this subcircuit simulates exactly like the ADS R component. Its only purpose is to provide a different symbol.

Caution

Do not modify intermediate subcircuits. They can be overwritten, without warning, any time you transfer a GENESYS schematic into your ADS project.

Non-Existent Mappings

Sometimes there is no mapping found for a particular GENESYS model. This happens for a variety of reasons: Vendor library parts for which there are no mapping rules. User-defined Verilog-A models for which there are no mapping rules.* Standard models that don't have a corresponding ADS component.* Standard models for which we have not yet created a mapping rule.

When no mapping rule is found, GENESYS emits an error. The schematic transfer continues, leaving a blank spot in the ADS schematic where the component should be.
Pay attention to these error messages. In most cases, the ADS schematic will still simulate even with missing instances. Most of the time, if you do simulate, the results will be unrealistic, signaling a problem. There can be cases where the simulation results appear somewhat reasonable even though the circuit is incomplete.

Non-Simulatable Components

To reduce the potential confusion of simulating circuits that have missing components, non-simulatable components are used. A non-simulatable component is an ADS component that will generate an error upon simulation in ADS. The symbol for a non-simulatable component looks like a normal ADS symbol, but it has an orange circle/slash symbol to indicate that it's non-simulatable.

If you do try to simulate, an error message will appear in the Status Server:

Error detected by hpeesofsim during netlist parsing.
illegal: valid characters in design names are alphanumeric or _`@#&+-=^
Instance `InstanceName' in design `\ProjectName\networks\DesignName' is a non-simulatable data-based model. It is a placeholder for a GENESYS component that could not be transferred to ADS.

To perform a simulation in ADS, you need to replace each instance of a non-simulatable component with an instance of a regular ADS component or with an instance of a subcircuit that you create to model the component.

For a comprehensive list, see Non-Simulatable Components in the Model Translation chapter.

Exporting TestBenches

When you export schematics from GENESYS to ADS, you have the option of exporting TestBenches. When this option is selected, GENESYS exports a TestBench schematic for every exported GENESYS schematic that has a GENESYS Linear simulation associated with it.

For instance, when you export a schematic named MySchematic and there is a linear simulation in GENESYS for MySchematic , then the exporter exports two schematics to ADS. One is MySchematic , and the other is MySchematic_TestBench . The testbench schematic is used to calculate the S-parameters of MySchematic . It contains an instance of MySchematic , Term components to terminate the instance, and an S-Parameter simulation controller with settings derived from the GENESYS Linear simulation.

Caution

Changes to a TestBench schematic in ADS will be overwritten if you re-export the TestBench schematic. To avoid overwriting changes, do not re-export TestBenches.

Benefit of using TestBenches

An ADS schematic can contain both circuitry and simulation control, so why use TestBenches for simulation control? Separating the simulation schematic from the circuit schematic makes the circuit schematic immediately reusable. If the simulation control components were placed on the circuit schematic, then the circuit schematic could not be used as a subcircuit without first deactivating the simulation components and the Term components.

Note

Only linear simulations are exported from GENESYS. Other simulation types (harmonic balance, transient, optimization, etc.) are not exported.

Using GENESYS Synthesis from ADS

To launch GENESYS Synthesis select Tools > GENESYS Synthesis from the schematic window.

You need to specify whether you want to create a new design or open an existing Workspace. If creating a new Synthesis design, ADS asks what type of synthesis you'd like to perform and then launches GENESYS preconfigured to perform the synthesis.

If you would like to specify an ADS substrate to copy, select the checkbox, then click the Specify Substrate button.

The Select Substrate dialog will appear. Specify which substrate you would like to copy and click OK . You should now see the name of the selected substrate appear in the Launch GENESYS Synthesis dialog, click OK .

GENESYS will start a new design while ADS runs in a separate window. When you are finished, refer to Transferring schematics from GENESYS to ADS.

Note

See GENESYS documentation for information on how to create/manipulate information in GENESYS.

Accessing EQUALIZE and S/FILTER

EQUALIZE and S/FILTER are compatible with ADS. However, they are not accessible from the ADS synthesis menu. To use them, start GENESYS by launching SPECTRASYS with a blank schematic. Once you are in GENESYS, follow the tutorials for these programs in the GENESYS online help. When you are done synthesizing your circuits, you should save your files and export to ADS using the File > Export > Export Schematic to ADS command in GENESYS.

Example using the GENESYS Synthesis link

The following section details how to design a Butterworth low pass filter using the GENESYS Synthesis Link.

Launch GENESYS Synthesis... from ADS menu bar.
Select the Create a New Synthesis Design option and change the Synthesis Type to Microwave Filter. If required, the substrate can be defined with GENESYS. However, an ADS substrate can be used by checking the Copy ADS Substrate to GENESYS box.
GENESYS is launched. The particular visual configuration may vary.
Accept the defaults by clicking OK . This will show the M/FILTER tool.
We are designing a low pass Butterworth filter, so select Butterworth from the Shape drop-down. Lowpass will be the default under Type . Subtype refers to the particular architecture that will implement the filter. The list of subtypes will vary with Type and Shape.
Our filter will be of the order 5, and have a cutoff frequency at 1 GHz. Select the Settings tab and fill in the information.
The design will model discontinuities in widths. Select the Options tab, and click the Select Manufacturing Process... button.
We choose to design our filter with standard microstrips.
The M/FILTER tool now prompts for a substrate. The design will use the factory substrate. Select Create New Substrate .
Select the Factory Defaults button and click OK .
We look at the summary tab and then press the Optimize button for design refinement.
After 500 iterations or so, we stop our optimization. We check the S11 and S12 characterization of our design.
The design schematic shows a sequence of microstrip lines of varying length and width, in a straight line. Between the microstrip lines are discontinuity modeling parts.
We will now export the schematic through ADS Link by selecting File > Export > Export Schematic to ADS .
Genesys insists that we save our workspace once.
After saving our workspace (.wsx) into the prompted ADS project folder under workspaces/synthesis, we export our schematic with the test bench by pressing the OK button.
Our schematic and test bench designs are now available in ADS. GENESYS gives a message saying that the transfer is complete. For information on the location of files exported from GENESYS refer to Folders used by the GENESYS Synthesis/SPECTRASYS link.
Note
Open ADS windows will be closed during export from GENESYS, only the main ADS window will remain. Any changes in the ADS windows will be saved in memory, unsaved modifications will not be lost.
The test bench shows as follows:
The schematic is a sub circuit between the two terminals in the test bench and can be viewed as a design.
Finally, after simulating the test bench, we plot the S11 and S12 characteristics of the synthesized microstrip filter.

Using SPECTRASYS from ADS

To launch SPECTRASYS select Tools > SPECTRASYS from the schematic window.

You need to specify whether you want to create a new design or open an existing Workspace. If creating a new System design, ADS asks what type of Template you'd like to use and then launches GENESYS to run SPECTRASYS. When you are finished, refer to Transferring schematics from GENESYS to ADS.

Note

Launching SPECTRASYS is a convenient way to start GENESYS with a blank schematic, even if you will not be using SPECTRASYS.

Note

See GENESYS documentation for examples and information on how to use SPECTRASYS.

Transferring schematics from GENESYS to ADS

You can transfer schematics from GENESYS to ADS using the File > Export > Export Schematic to ADS command in GENESYS. GENESYS displays a dialog box showing all instances of ADS with open projects. You first select the instance that you want (if you have more than one running), then you select which designs to export to ADS. When you click OK, the selected schematics are transferred to ADS. GENESYS posts a message saying that the transfer is successful. For information on locating the transferred files refer to Folders used by the GENESYS Synthesis/SPECTRASYS link.

Note

Open ADS windows will be closed during export from GENESYS, only the main ADS window will remain. Any changes in the ADS windows will be saved in memory, unsaved modifications will not be lost.

If no run-time link exists

GENESYS automatically establishes it, if possible. The link can be automatically established if there is an ADS session running and that session has a project open.

If ADS is not running

You should launch ADS. Once ADS is running and has an open project, go to GENESYS and select File > Export > Export Schematic to ADS .

If there is more than one ADS session running

GENESYS will ask you which session to link to. The ADS sessions are distinguished using the project name.