Accuracy of electromagnetic analysis for a MMIC Lange coupler

Accuracy awareness of electromagnetic modeling and analysis plays an important role in designs where strict control of parameters is needed. The examined structure is a Lange coupler made in MMIC technology. An additional feature of the coupler is the use of meander lines, resulting from practical layout space limitations. Due to strong coupling, the parameters of the coupler are very sensitive to settings and small errors in computer modeling. The possibility to achieve accurate electromagnetic simulation results, compared with measurements, for MoM and FDTD methods and their different implementations are analyzed, together with consequences and recommendations regarding modeling and interpretation of results.