Pattyn, TimTimPattynSun, XiaoXiaoSunBeyne, EricEricBeyneDe Zutter, DanielDanielDe ZutterHuynen, MartijnMartijnHuynenVande Ginste, DriesDriesVande Ginste2026-09-082026-09-082025979-8-3315-8515-02165-4107https://imec-publications.be/handle/20.500.12860/60267In this contribution, an enhanced 3-D differential surface admittance operator is proposed, facilitating accurate modeling of piecewise homogeneous cuboidal objects. By exploiting the analytical properties of entire-domain basis functions, material interfaces are effectively eliminated from the formulation, leading to a reduction in the number of unknowns without compromising the accuracy of the operator. After a validation of the novel approach, its effectiveness is demonstrated through the analysis of the impedance responses of on-chip interdigital capacitor structures. Index Terms-3-D differential surface admittance (DSA) operator, single-source boundary integral equation (BIE), piecewise homogeneous media, material interfaces, on-chip capacitorengProceedings paper10.1109/epeps63858.2025.11346718WOS:001798607700040