An In-Depth, Theoretical Investigation Into Modeling Metal-Insulator-Metal Capacitors Using Symmetric Coupled Lines in a Homogeneous Medium Model

In monolithic microwave integrated circuits (MMIC) design, a metal-insulator-metal (MIM) capacitor is one of the key passive components. Research on modeling MIM capacitors in an accurate yet efficient fashion has been around for years. Models for series capacitors of small electrical length have been well established. In the authors´ previous work was pioneered the novel approach to modeling shunt capacitors of significant electrical length on multiple grounding vias with the effect of lossy media incorporated. With this in mind, this letter further expands on, and provides a significant supplement with, the previous works. At the core of this letter is to gain an in-depth, theoretical insight into the rationale that, under the condition of tight conductor coupling, asymmetric coupled lines in an inhomogeneous medium reduce to symmetric coupled lines in a homogeneous medium.