This paper presents a fast analog circuit analysis algorithm, fundamental circuit-based circuit analysis, for circuits being repeatedly modified and verified in product development. The algorithm reuses previous circuit simulation result on successive changed circuit analysis to achieve simulation operation reduction. The algorithm is implemented with SPICE simulator on linear and nonlinear circuit applications with the proposed device delta models. The experiments show that the algorithm increases the speed of the circuit simulation five to ten times over directly simulations under the same simulation accuracy.

A novel circuit simulation methodology, incremental circuit SPICE analysis, is presented with the foundational circuit simulation algorithm. When a circuit in design is modified from one version to another, only the change in the circuit is simulated and analyzed. The approach is well applied into design process for circuit parametric modification and functionality verification. By reusing simulation result from successive version, the algorithm reduces the duplicated operations in simulation. The examples show the new approach increases simulation speed about 10 times over the traditional method.

An innovative algorithm for computer-aided circuit design is presented in this paper. The algorithm is applied to "relative" circuits during optimal circuit design process to reduce circuit simulation time. The new concepts of "relative" circuits, fundamental circuit, derivative circuit, and delta circuit, are introduced. A practical implementation approach is developed with a Spice simulator, accordingly. The algorithm can be adapted to statistical designs or optimal designs. An example is given to prove the correctness and efficiency of the algorithm.