SPECS2: An Integrated Circuit Timing Simulator

Abstract

SPECS2 is a prototype implementation of a new timing simulation and modeling methodology. SPECS2 (Simulation Program for Electronic Circuits and Systems 2) is a tree/link based, event-driven, timing simulator. A modeling technique, which is predicated on the conservation of charge and energy, is employed to produce table models for device evaluation. The tables may be constructed to model devices at any desired level of detail. Thus, SPECS2 is a variable accuracy simulator. Grossly differing accuracy requirements may be specified for different runs and also mixed over different parts of the same circuit. SPECS2 implements a novel oscillation detection and suppression scheme that prevents algorithmic oscillation, while leaving real circuit results undistorted. SPECS2 takes advantage of the tree/link formulation of the circuit equations to provide a formal and general approach to timing simulation. It encounters no special problems with floating capacitors or transmission gates. Further, SPECS2 provides the framework for a generalized macromodeling and simulation capability.

This work was supported by the CMU CAD Center Industrial Affiliates and the Semiconductor Research Corporation.