Mixed-technology system-level simulation

This paper describes a computationally efficient method to simulate mixed-domain systems under the requirements of a system-level framework. The approach is the combined use of Modified Nodal Analysis (MNA) for the representation of a mixed-technology device and piecewise linear (PWL) techniques to overcome the costly numerical evaluation found in conventional circuit or device simulators. This approach makes the simulation computationally fast, as well as more stable when compared with traditional circuit simulation. The PWL solver, based in the frequency domain, is more robust to inconsistencies in initial conditions and impulse changes when compared to integration based solvers in the time domain. The advantage of this method is that the same solver enables the integration of multi-domain devices (e.g., electrical, optical, and mechanical) in the same simulation framework. The use of this technique for the simulation of multi-domain systems has proven to give better performance in simulation time when compared to traditional circuit simulators with a relatively small decrease in the level of accuracy. Comparisons with traditional solvers, such as SPICE, show two to three orders of magnitude speedup with less than 5% relative error. The ability to adjust the level of accuracy, either by varying the sampling rate or the number of regions of operation in the models, allows for both computationally fast and in-depth analysis in the same CAD framework.