Some AMS terminology

An aspect of AMS which extends to mixed-signal in general is that a 
signal (representing the state of a wire in the actual hardware) can be 
viewed in multiple ways, i.e. it is at the same time digital (1/0) and 
has voltage (1.5/0.0V) different instances see the same object in 
different ways. The abstraction used is that all interaction with a 
signal from (a process in) an instance is through /drivers /and 
/receivers /- the latter object does not appear in other HDL 
definitions. A signal /driver /in an analog process is usually called a 
/contribution /(e.g. some amount of current).

To make the mixed signal simulation work a resolution function is 
applied to all the drivers/contributions such that it can be resolved in 
the domain of highest accuracy (analog) and then is down converted (if 
necessary) to the domains of each receiver - i.e. for AMS you wrap the 
digital drivers in D->A converters and the digital receivers are 
implemented as A->D converters.

Key features of the approach are:

    Interconnect is actually type neutral, the type is associated with 
the drivers and receivers
    Resolution is flat (port boundaries/hierarchy should be ignored)

Drivers and receivers also have a /discipline /which indicates which 
their physical nature (electrical, magnetic, fluid etc.), drivers and 
receivers of different disciplines cannot be mixed. Disciplines 
themselves are constructed from a pair of /natures/ representing 
potential and flow e.g. voltage/current.


For general cross-language simulation to work properly it is desirable 
that a similar approach is taken when communicating signal values, i.e. 
signal values need to be exchanged as separate driver/receiver values 
rather than as a locally resolved value.

Kev.



-- 
This message has been scanned for viruses and
dangerous content by MailScanner, and is
believed to be clean.