History and purpose of VHDL-AMS
(history,
purpose, new
mechanisms)
The history:
-
VHDL (Very High Speed Integrated Circuit Hardware Description
Language) a language for the description of digital circuits
-
with the VHDL, it is possible to simulate and
synthesize the digital circuits for different technologies
-
the already created entities are archievable in libraries
and may be adapted for reuse in complex systems
-
the first standardization of VHDL has taken place in 1987,
the second in 1993
-
in 1993 a specific group has been organized to develop
an extension to the language that could allow the description and
the simulation of digital-analog hybrid systems
-
this expanded release has for name VHDL-AMS (AMS:
Analog and Mixed Signal) and has been standardized recently (1998)
as IEEE - VHDL 1076.1. standard (http://www.vhdl.org/vi/analog)
The purpose
-
to provide a hierarchical description and continuous and
mixed system simulation
-
to support the modeling of different levels of abstraction
in electrical and some non-electrical domains (e.g. systems built from
hydraulic or mechanical components)
-
the analog circuits can be modeled by systems of differential
and algebraic equations(DAE)
-
the resolution of these systems had to include the management
of discontinuities
New
mechanisms added to VHDL 1076.1:
-
the creation of an analog resolution nucleus to solve systems
of equations, and a notation for these systems of equations
-
the creation of new objects - quantities to
express differences of potential at terminals of a path and the crossing
it current as well as the notion of tolerance
-
a redefinition of the cycle of simulation for the simulation
of hybrid systems and creation of simultaneous statements
(assignments)
