Investigation of the nonlinear circuit analysis by electromagnetic topology based on harmonic balance

Over the past few decades, several studies have been made on the nonlinear analysis of electronic circuits. In microwave and RF circuits, components such as limiting amplifiers, oscillators, doublers, and mixers rely on device nonlinearity for proper operation. The problem of analyzing and designing nonlinear circuits is usually more complicated than it is for linear circuits. Therefore, this paper is intended as a proposal of an improved numerical technique for large and nonlinear circuit analysis using electromagnetic topology (EMT) based on harmonic balance (HB). HB has been used for the analysis of nonlinear system. However the HB needs the large number of variables that must be optimized, and this makes the method impractical for large systems. On the other hand, EMT is an effective method for analyzing large systems using volume decomposition. The EMT has been studied for linear analysis [1], but very few attempts have been made at the nonlinear circuit analysis. Therefore, a combination method for EMT and HB is proposed. In the proposed method, EMT and HB communicate real-time: the updated voltage result by the HB are excited to the EMT as sources, and the computation results by the EMT are substituted for computing linear and nonlinear current in the HB until errors are negligibly small. The merits of the proposed method are fast computation time, reduced memory requirements, and compatibility with other simulation and experiment in comparison with conventional methods. To verify the proposed method, the analysis of a voltage doubler circuit was performed at 500MHz. The analysis results were compared with experimental results, and the results indicated a validity of the method.