High-confidence validation
of analog and mixed-signal circuits



Work Packages





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Work Packages

The project intends to build an experimental platform for validating the correctness of analog and mixed-signal circuits, a component of increasing importance for the functioning of modern embedded system. The platform will combine two technologies currently being developed by the partners: an effcient and physically-accurate simulator for large analog and mixed-signal circuits and the methods for covering the state space of such circuits by choosing appropriate input signals. The project will be composed of the following three activities:
  1. Development of search-based methods for validating large-scale continuous and hybrid systems
  2. Development of numerical analysis techniques for non-smooth dynamical systems
  3. Tool development (including generation of circuit equations from models, optimization, etc.) and application to circuit benchmarks.

Principal work packages

WP1- Coverage guided simulation.
In order to measure simulation quality, we define coverage criteria that reflect the properties to verify. These criteria are then used to guide the simulation, which enables us to guarantee some coverage and convergence (in comparison with exhaustive verification). This work will build upon a coverage guided simulation method for continuous and hybrid systems, which is being developed in VERIMAG. The method is inspired by the probabilistic path and motion planning methods in robotics and inherits their completeness properties.

WP2- Verification by simulation.
The existence of metrics on the system state space, which is natural for continuous and hybrid systems, allows us to capitalize on the recently developed concept of bisimulation metrics and infer all the possible behaviors of the system in a neighborhood of a simulated trajectory. Hence, by a finite number of simulations one can produce results as strong as those obtained by exhaustive verification, such as deciding whether the system is correct under all possible disturbances. These bisimulation metrics can be used to define strategies for exploration of the space of trajectories as well as for counter-example guided refinement. Several strategies will be proposed and their (theoretical and experimental) performance in verifying di erent types of properties, such as those expressed in timed temporal logics, will be analyzed. Also, a part of our work will aim at proposing necessary algorithmic approaches to the computation of these bisimulation metrics.

WP3- Advanced numerical analysis techniques.
A performant simulation tool must rely on e cient and accurate techniques for resolving circuit equations. The state-of-the-art SPICE simulator is prone to convergence problems when the dynamics of the circuit has fast variations caused by components with stiff  characteristics. Within this project, the INRIA-BIPOP team will address these problems with a special set of models and dedicated algorithms known as the non-smooth approach. Its application to the simulation of mechanical systems has already been proved successful, and the goal of this work package is to adapt this technology to electrical systems. This adaptation involves, on one hand, the resolution techniques specific to the circuit dynamics and, on the other hand, an optimal extraction of the circuit equations in a required form from the commonly-used description formalisms such as netlists. The techniques and tools developed in this work package will serve as the computation engine, on top of which the methods developed in the work packages WP1 and WP2 are used to guide the simulation process.

WP4- Tool development and application to analog and mixed signal circuit analysis.
The motivation for choosing this new but increasingly important application domain is that on one hand these circuits can be naturally modeled using hybrid systems and, on the other hand, we believe that the new simulation tools developed in the context of the project will contribute to enhance the automatization and reliability of the design of analog and mixed-signal circuits. The goal of this work package is to integrate all the results and tools obtained in the work packages WP1, WP2, and WP3 into a tool box with a user-friendly graphical interface. The tool box will then be tested on various benchmarks of analog and mixed signal circuits.