An expert system approach to mixed mode design partitioning

This paper brings together object oriented design, qualitative reasoning and the expert system to provide a CAD tool that has advantages for mixed signal design. The combination of object database and qualitative reasoning produce analogue object cells from a generic VHDL-AMS description. The expert system has two aims: (i) to assist in the design of the analogue object cells by shaping the implementation of the cell to a specific application and (ii) to provide information to the cost function on how the cost function can be modified to improve its effectiveness. The partitioning of the design is carried out by multiple modifications to the cost function so that it provides the most accurate representation of the costs of a particular cell which can then be selected as analogue or digital. The system is applied to the phase locked loop showing code segments for the voltage controlled oscillator. We conclude that knowledge based systems have a role to play in system level design.