Virtuoso AMS Environment User Guide

Updating Legacy SimInfo for Analog Primitives

connected to gnd!. Further assume that the G terminal is unconnected. The port connection list for the instance is written to the netlist as

(sig1,,sig2,cds_globals.\gnd! )

If the nmos device did not have a termOrder entry, the port connection list for the instance might be written to the netlist as

(.S(sig2),.D(sig1),.B(cds_globals.\gnd! ),.G())

The cdsSpice and spectreS (spectreSocket) simulators support programmable nodes, which are specified in thetermOrder entry as the argument to Progn (i.e., Progn (nodeName)).

Progn is not supported by the AMS netlister. Programmable nodes must be represented as extraTerminals in the ams simInfo. If Progn is encountered by the AMS simInfo from Spectre conversion tool, it issues a warning that manual editing of the ams simInfo is necessary.

Special Handling of model, modelName, modelname, and componentName

Although you can specify the model, modelName, modelname, and componentName parameters in the ams simInfo *Parameters fields, they are not written to the Verilog-AMS netlists. Instead, they change the module name of the instance to which they apply.

Another important difference in the treatment of model, modelName, modelname, and componentName is the mapping of the name. Names specified as values of themodel, modelName, and modelname parameters are checked for legality in the Verilog-AMS language. If necessary, these names are escaped. For example, if an instance has the property model=4nmos, 4nmos is mapped to Verilog-AMS as \4nmos, because Verilog-AMS identifiers cannot begin with a digit.

Note: If the device is a primitive that supports model passing semantics, the associated model, modelName, or modelname parameter must be listed in the instParameters field. This requirement holds even though model, modelName, and modelname parameters are not passed parameters and are treated specially.

Names specified as values of theams simInfo componentName field are not mapped. They are written to the netlist verbatim. This behavior supports the handling of SPICE and Spectre primitives that have the same names as Verilog-AMS built-in primitives. SPICE and Spectre primitives such as these can be supported by providing the complete set of formatting instructions via the termOrder field.

For additional information about these parameters, see “Passing Model Names as Parameters” on page 134.

Virtuoso AMS Environment User Guide

Updating Legacy SimInfo for Analog Primitives

Converting an Existing Analog Primitive Library

Cadence provides a conversion tool that you can use to add ams simInfo information to an existing analog primitive library. This new information is derived from existing spectre simInfo data.

To use the conversion tool

1.From the CIW, choose Tools – Conversion Tool Box. The Conversion Tool Box window appears.

2.Click AMS simInfo from Spectre.

Virtuoso AMS Environment User Guide

Updating Legacy SimInfo for Analog Primitives

The Create AMS from Spectre form appears.

3.From the Library name cyclic field, select the analog primitive library that you want to update.

4.Choose either Process all cells in the library or Process only cells with the following views.

Virtuoso AMS Environment User Guide

Updating Legacy SimInfo for Analog Primitives

If you choose the latter, type in one or more views. Only cells that have at least one of the specified views are processed. Cells that do not have any of the specified views are unchanged and any existing ams simInfo is left untouched.

5.Enable Overwrite AMS simulation information if the library already has ams simInfo data.

6.In the Save existing information in the following file field, type the name of a backup file to be created by the conversion tool.

If necessary, you can use the backup file to restore the originalams simInfo.

7.Specify conditions for the conversion tool to use when determining whether a cell is a primitive.

The following conditions often indicate that a cell is a primitive and ought to be marked as such by having the isPrimitive field of theams section of the CDF simInfo set to t. However, this automatic determination is not always correct, so Cadence recommends that you check the accuracy. You might need to manually set isPrimitive to the opposite value.

a.Select If any of modelname/model/modelName are found if you want the netlister to use this condition for determining whether a cell is a primitive.

b.Select If the cell has a "spectre" view to have the netlister use this condition.

8.Click OK.

The AMS simInfo from Spectre conversion tool traverses the library, reporting which cells it creates ams simInfo data for and which ones it skips. When a cell is skipped, the AMS simInfo from Spectre conversion tool reports the reason.

The conversion tool first copies data from the fields of thespectre simInfo that are common to the ams simInfo:

■otherParameters

■instParameters

■componentName

■termOrder

■propMapping

It then examines the netlistProcedure field in thespectre simInfo data. The conversion tool recognizes and converts the following analogLib procedures:

■spectreCCPrim

Virtuoso AMS Environment User Guide

Updating Legacy SimInfo for Analog Primitives

■spectreFsrcPrim

■spectreMindPrim

■spectreNportPrim

■spectrePolyCntrlPrim

■spectrePortPrim

■spectrePortSrcPrim

■spectrePwlsrcPrim

■spectreSCCPrim

■spectreSVCPrim

■spectreSrcPrim

■spectreVandISourcePrim

■spectreWindingPrim

The conversion tool segregates parameters referenced by these procedures into the various ams fields:instParameters, enumParameters, referenceParameters, stringParameters, and so on. If there is no netlistProcedure for a cell or if the netlistProcedure is not one of those listed above, the conversion tool leaves the copied spectre simInfo data in the corresponding common ams simInfo fields. In such cases, you must manually edit the information to ensure that the parameters are in the correct fields.

The AMS simInfo from Spectre conversion tool does not fill in theisPrimitive field of the AMS simulation information. If the library you are converting contains components that are primitives, you need to set the value of the isPrimitive field for those components to t. For more information, see “isPrimitive” on page 592.

Finally, if the cell has a spectre view, the conversion tool examines it to determine if it has more terminals than the symbol view. If so, an entry is made in the extraTerminals field of the ams simInfo that represents the additional terminals.

To manually edit ams simInfo data,

1.From the CIW, choose Tools – CDF – Edit. The Edit Component CDF window opens.

2.Fill in the library and cell information.

3.Set CDF Type to Base.

Virtuoso AMS Environment User Guide

Updating Legacy SimInfo for Analog Primitives

Except for the amsExcludeParams parameter, the AMS environment does not use

Library or User CDF information.

4.Click the Edit button in the Simulation Information part of the form.

The Edit Simulation Information form appears.

If spectre simInfo data existed when the conversion tool ran and the netlistProcedure

field was empty or contained a procedure other than those listed above, theams fields that correspond to spectre simInfo fields contain data copied directly.

5.Examine the instParameters and otherParameters fields for parameters that should be moved to the arrayParameters, enumParameters, stringParameters, or referenceParameters fields and make the appropriate changes.