Formal Verification of Analog and Mixed Signal Designs Using SPICE Circuit Simulation Traces

Analog and Mixed Signal (AMS) designs can be formally modeled as hybrid systems [45] and therefore formal verification techniques applicable to hybrid systems can be deployed to verify them. An extension to a formal verification approach applicable to hybrid systems is proposed to verify AMS designs [31]. In this approach formal verification (FV) is carried out on an AMS block using simulation traces from SPICE, a simulator widely used in the design and verification of analog and AMS blocks. A broader implication of this approach is the ability to carry out hierarchical verification using relevant simulation traces obtained at different abstraction levels of a design when modeled in appropriate platforms. This enables a seamless transition of design and verification artifacts from the highest level of abstraction to the lowest level of implementation at the transistor level of any AMS design and a resulting increase in confidence on the correctness of the final implementation. The proposed approach has been justified with its applications to different AMS design blocks. For each design, its formal model and the proposed computational techniques have been incorporated into CheckMate [11] - a FV tool for hybrid systems based on MATLAB and the Simulink/Stateflow framework from MathWorks. A further justification of the proposed approach is the resulting improvements observed in terms of reduced verification time for different specifications in each design.