A full-wave analysis of interdigital capacitors for planar integrated circuits

A finite-difference time-domain (FDTD) model has been developed to determine the circuital and electromagnetic compatibility performances of a large class of interdigital capacitors (IDCs). The model, based on a new conformal FDTD scheme, employs the free-space dyadic Green´s functions to analyze the field behavior near and far from the FDTD computational domain. Using the proposed model, various IDC structures have been analyzed and a frequency-independent equivalent circuit, which include surface and volume wave effects, has been introduced. A good agreement with numerical results already available in literature has been found.