Designing circuits that are used in products such as digital signal processors requires making predictions of how the individual circuit elements, such as transistors, will behave. Modeling individual circuit elements requires making predictions of how the fabrication process affects the behavior of the resulting circuit elements. By making predictions, circuit designers can understand how the circuit will operate without the time and expense of actually building the circuit. Modeling circuits is problematic when the characteristics of the individual circuit elements are not known. Known methods for modeling such circuit elements, however, have not been completely satisfactory with respect to efficiency and accuracy.
Known methods for predicting circuit element characteristics include using post-silicon models and using process and device simulators. Post-silicon models predict how a process affects the behavior of a circuit element using measurements from existing circuit elements fabricated under the same process. These predictions may be made using a standard circuit transistor element model. A problem with this method is that it cannot be used to make predictions about circuit elements fabricated using a different process. Alternative models, generated using process and device simulators, may be used to predict the behavior of circuit elements fabricated under different processes. These process and device simulators use equations describing the underlying physics to predict the effect of a process on a circuit element and its corresponding effect on the circuit. Prior models generated using these simulators, however, were not sufficiently accurate.
While these approaches have provided improvements over prior approaches, the challenges in the field of circuit fabrication has continued to increase with demands for more and better techniques having greater efficiency and accuracy.
Design and analysis of integrated circuit systems including the chip, package and printed circuit board, becomes more complex as the size of the system is reduced, and the number of components and complexity increases. Modeling is used to simulate performance and operating characteristics of a particular integrated circuit system design. Modeling provides an analysis tool that may assist a designer in evaluating cost and performance criteria, to determine the economic feasibility of meeting or exceeding particular specifications, without actually manufacturing a chip or package. In this manner, the operation and performance of the package is simulated, using one or more of various techniques.
Unfortunately, accurate modeling of integrated circuit packages by known methods require that the design of many components be substantially complete, in order to account for their effect on the operation of the system. For example, many current solutions for analyzing electrical characteristics of a package, use post-layout extracted netlist(s) or computer generated models that are based upon the full package geometry. Both of these processes generate netlists that are too large to be practical for doing multiple simulations and evaluating alternatives. The extracted netlist is obtained too late in the design stage to be of assistance in making architectural design decisions. The design of such systems takes a significant amount of time and resources, that may be lost if the results of the analysis are unfavorable. Moreover, accurate modeling by known methods apply to small portions of the design, but are impossible to perform on the entire design, based upon the amount of data and number of calculations required of the particular analysis tool(s).