The numerical simulation of entire printed circuit boards (PCB) with the aid of the finite element method (FEM) or the finite difference time domain (FDTD) method is not feasible by currently available computer resources (size of memory and clock rate) of personal computers. Accurate investigations have shown that individual components (i.e. crosstalk of microstrips or a nonlinear transformer) represent a big challenge in numerical simulations. On the other hand the requirements in the design of PCBs (higher clock rates, higher circuit densities, multilayered boards, etc.) increase continuously.
The aim of the project MultiACCESS is to facilitate a sufficiently accurate simulation of the essential electromagnetic properties (signal integrity, minimized transmission delay, electromagnetic compatibility, etc.) of large PCBs in a broad frequency range routinely in the design phase.
Large PCBs are employed in, among others, telecommunications. Data transfer by means of broad band DSL still exhibits large growth rates. Solutions are realized providing free access between different service-levels (ADSL, SHDSL, VDSL) and thus help to optimize the costumers costs. Thus, the development of powerful numerical methods for the design of PCBs is of great importance.
The approach is to provide adequate circuit models extracted from accurate field simulations. The simulation times of circuit models are essentially smaller than those of the corresponding field models and thus, are suitable to assist the design of PCBs.
For the field simulation individual components on PCBs are considered separately and simulated by FEM in the frequency and in the time domain or by the FDTD in the time domain. Hereby the components are appropriately terminated by transfinite elements for FEM or by surface impedances for FDTD.
Based on the field simulations of the individual components circuit representations in terms of input impedances, scattering parameters, etc. are extracted. Subsequently the individual circuits are assembled to one large circuit representing the entire PCB.
Additionally, the computation times for the solution of the equation system resulting from FEM are attempted to be minimized using geometric multigrid techniques.