2.2 Broadband Modeling

The choice of the equivalent circuit is an important step by the modeling. In order to take the high frequency characteristics of coplanar structures into account, a broadband equivalent circuit is necessary. This is only possible if all parasitic effects are considered in the selected model. The selection of such broadband models is demonstrated in Figure 2-2 for more complex structures like spiral inductors. For a large number of turns, the use of a simple equivalent circuit (consisting of a single pi-network) would lead to the limitation of the validity range. Therefore, a more accurate equivalent circuit is applied, where each turn of the inductor is represented by a pi-network. The electrical coupling between the turns (partially caused by the air bridge) is considered by the capacitance C_g between the ports.

Figure 2-2. Broad band modeling of a coplanar spiral inductor

[close window]

[2.3 Shielding and Discretization ]