Virtuoso AMS Environment User Guide
Netlisting
Specifying Parameters to be Excluded from Netlisting
This section describes how you can precisely specify parameters to be ignored during netlisting. Depending on your needs, you can specify such parameters for particular cells, for particular designs, for entire libraries, or for any combination of the three.
■To specify ignored parameters at the cell level, you use the excludeParameters field in the AMS simInfo. For more information, see “excludeParameters” on page 590.
■To specify ignored parameters for a design, you use the amsExcludeParams variable in the ams.env file. For more information, see“amsExcludeParams” on page 381.
■To specify ignored parameters at the library level, you use a CDF parameter called amsExcludeParams in the base library CDF. For more information, see the following section, “Ignoring Parameters for Entire Libraries.”
Ignoring Parameters for Entire Libraries
To specify ignored parameters at the library level, you use the following steps to add a CDF parameter called amsExcludeParams to the base library CDF.
1.From the CIW, choose Tools – CDF – Edit to open the Edit Component CDF form.
2.In the Edit Component CDF form, select Library as the CDF Selection and Base as the CDF Type.
3.Type in the name of the library for which parameters are to be ignored.
April 2004 |
137 |
Product Version 5.3 |
Virtuoso AMS Environment User Guide
Netlisting
After these steps, the Edit Component CDF form looks like this.
4.Click Add.
The Add CDF Parameter form appears.
April 2004 |
138 |
Product Version 5.3 |
Virtuoso AMS Environment User Guide
Netlisting
5.In the Add CDF Parameter form, choose string for paramType, and type in amsExcludeParams for name, and yes for editable. In the defValue field, type in the parameters to be ignored.
6. Click OK to close the Add CDF Parameter form.
April 2004 |
139 |
Product Version 5.3 |
Virtuoso AMS Environment User Guide
Netlisting
7.The Component Parameters pane in the Edit Component CDF form changes to look like this, indicating that the parameters are to be ignored whenever they are found associated with a component in this library.
8. Click OK to close the Edit Component CDF form.
Example: Specifying Parameters to Ignore
The effects of the three methods of specifying parameters to exclude are additive. For example, given
■In the simInfo field for the cellcell1, the excludeParameters field set tof
■In the ams.env file for the design,amsDirect amsExcludeParams string "a b c"
■In the base library-level CDF of the library mylib, amsExcludeParams set to d e
the final list of parameters excluded while processingmylib.cell1:schematic is a, b, c, d, e, and f.
Assuming that no parameters are excluded in the excludeParameters simInfo field for mylib.cell2, the excluded list for that cell is a, b, c, d, and e.
Assuming that no parameters are excluded in the excludeParameters simInfo field for cell3 and that the mylib2 library does not have any amsExcludeParams parameters set, the excluded list for mylib2.cell3 is just a, b, and c.
Preparing to Netlist User-Defined Functions
By default, the netlister returns an error when it encounters a call to a Spectre or SPICE userdefined function (UDF) in a schematic because AMS Designer does not support this usage. However, at your request, these UDF calls can be converted into macro references, which are
April 2004 |
140 |
Product Version 5.3 |
Virtuoso AMS Environment User Guide
Netlisting
supported by AMS Designer. If you take this approach, you must ensure that the referenced macros are actually defined and that the definitions are accessible during netlisting.
1.Add the variable netlistUDFAsMacro to the ams.env file in your working directory, with the value set to t.
amsDirect.vlog netlistUDFAsMacro boolean t
This variable setting tells the netlister to convert the UDF calls into macro references. For more information, see “netlistUDFAsMacro” on page 456.
2. Create a file containing the definitions for the macros.
Use formats such as the following, beginning each definition with‘define and enclosing the actual function in parentheses.
‘define mod(a,b) ( (a) - (b)*ceil(((a)+0.5)/(b)) ) ‘define int(a) ( (abs(a)==(a)) ? floor(a) : ceil(a) )
3. Add the new definitions file to the list of files included in netlists.
April 2004 |
141 |
Product Version 5.3 |
Virtuoso AMS Environment User Guide
Netlisting
For guidance, see “SettingTemplate Header and File Include Options” on page 81. For example, if your definitions file is namedudf_macros.vams, you might set up the
Template pane like this to include the file in generated netlists.
4.Ensure that the definitions file is found by using theInclude Directory table accessed by choosing Compiler – Verilog-AMS – Macros/Includes in the AMS Options
Categories pane. For guidance, see “Specifying Macros and Specifying Directories to be Searched” on page 104.
April 2004 |
142 |
Product Version 5.3 |