1. VHDL-AMS Reballoting 1076.1 FDL'03, 9/24/2003 Ernst Christen

2. © 2003 Synopsys, Inc. (2) Reasons for Reballoting IEEE Std. 1076.1-1999 was approved in 1999 IEEE Standards must be reaffirmed every 5 years

3. © 2003 Synopsys, Inc. (3) Necessary Updates to IEEE Std. 1076.1-1999 Synchronization with IEEE Std. 1076-2002 Correction of errata  8 page errata sheet, published at eda.org/analog Definitional errors (including examples) Typographical errors Layout issues  Several more errata

4. © 2003 Synopsys, Inc. (4) Enhancements to Consider Postponed requirements  Handling of mixed nets  Support for "analog" and "digital" architecture for an entity Problem is that ports of entity are unchangeable

5. © 2003 Synopsys, Inc. (5) Mixed Nets A net where participating objects are of different object classes  signal  quantity  terminal Compare with VHDL net where all participating objects are signals  Types may be different

6. © 2003 Synopsys, Inc. (6) Handling of Mixed Nets Insert conversion model between disparate objects  Conversion model defines semantics of mixed connection Can be arbitrarily complex and include, in addition to value "translation", loading effects, power supply dependency, etc.  Note that signal ports and quantity ports are directional, but terminal ports are not

7. © 2003 Synopsys, Inc. (7) Mixed Nets: Local Focus Define semantics of a port association element whose formal and actual are of different object class Advantage  Could follow type conversion/conversion function paradigm Disadvantage  Information loss if association elements at different levels of hierarchy are involved

8. © 2003 Synopsys, Inc. (8) Mixed Nets: Global Focus If mixed net includes a terminal, convert net to a node, otherwise convert net to a quantity net Insert conversion models between the net and the objects connected to the net that have a different object class Advantage  Best approach possible Disadvantage  Multiphase elaboration  Definitional difficulties with conversion fcts

9. © 2003 Synopsys, Inc. (9) Mixed Nets: Global Focus: Example tt s q t s s

10. © 2003 Synopsys, Inc. (10) Mixed Nets: Global Focus: Example tt s t q s s conversion models

11. © 2003 Synopsys, Inc. (11) Mixed Nets: Global Focus: Example tt s t q s s