The development of a mixed signal design tool

The Plessey Design Modelling (PDM) System was devised to enable the rapid development of a mixed analog digital ASIC. Traditional methods of IC design development are breadboarding and simulation. The simulation of a design has advantages over breadboarding in that the design is captured in software, enabling design management, checks, typical, best and worst case simulations, and changes that can be quickly made. However, a mixed analog and digital design usually presents a discontinuity in systems proving due to the separation of digital and analog sections for simulation, and this can lead to errors. Hardware description languages are available to model a mixed signal design, but they are expensive and do not offer the required accuracy. Mixed signal simulators are indeed beginning to emerge, but are as yet relatively expensive. Simulation has the disadvantage that the system cannot be evaluated in real time whilst interacting with the external devices. The PDM system was developed to maximise the advantages of both breadboarding and simulation, enabling a design to be captured, evaluated and modified whilst retaining full control, in a fast efficient manner