Integrated circuit design has evolved to the stage where large, complex, analog and digital functionalities are implemented on a single chip or as an integrated chip set. Besides the mixed signal nature of the designs, the analog sections also include continuous-time and discrete-time components. Thus, for analysis of these integrated modules, all encompassing simulation capabilities are required that address, not only transient analysis of mixed analog-digital circuits, but frequency domain analysis as well. In this paper, we present mechanisms for multilevel and mixed-domain simulation of analog systems tied in with mixed analog-digital simulation. We then describe the implementation in the form of an open-ended and expandable simulation framework, iMACSIM. A simulation backplane is used to provide a general event-processing and scheduling framework that ties together the various algorithms necessary for simulation of various classes of circuits in different analysis regimes.

The authors describe a new program called iMACSIM which allows multi-level, mixed-domain simulation of analog integrated circuits. The program performs the simulation of different subcircuits at the behavioral, functional, and electrical levels concurrently. It also enables some parts of the circuit to be simulated using discrete-time algorithms while other portions are processed by continuous-time techniques. Simulations are presented to demonstrate the functionality of the program.>