Simulation Overview

CST PCB STUDIO incorporates three different solver techniques to account for all kind of PCBS. Single- or two layer PCBs are normally designed without any special ground reference layers and therefore dedicated to the lower- or medium frequency range. The method best suited to this kind of application is the quasi-static Partial Element Equivalent Circuit method (PEEC). The program generates equivalent circuits out of any selected combination of conductors.  Skin effect and dielectric loss are modeled in both the frequency and the time domain.

A 2D transmission line modeling technique (2DTL) is offered to analyze classical signal integrity issues on high-speed multilayer boards including time delay, reflection and crosstalk effects on multiple transmission lines. The program automatically performs the partitioning and decides on adequate segments where the transmission line parameters should be calculated.  

In order to account for classical power integrity issues, a special modeling technique dedicated to the analysis of power distribution networks (PDN) in multi-layer PCBs is offered. Given a set of PDN nets to be characterized, the full-wave three-dimensional Finite Element Frequency Domain solver (3D FE FD) is able to compute PDN impedances.

Based on the mentioned solver techniques, CST PCB STUDIO provides two different simulation workflows:

Standard Workflow: Separated Modeling

This workflow separates two different phases. First, one of the solver techniques mentioned above is used to generate an equivalent circuit. In a second step, the equivalent circuit model can be used within a circuit simulation in CST DESIGN STUDIO (or an external SPICE compatible network simulation tool). Three different solver types support the separated modeling and circuit simulation workflow:

• 2DTL (2DTL)

• 3DPEEC (3DPEEC)

• 3DFEFD (3DFEFD)

In addition to the equivalent circuit generation, there is a similar workflow enabling the export of a selected geometric structure to CST MWS STUDIO. The corresponding workflow is called:

• Export to MWS (Export_to_MWS)

The main advantage of the separated modeling is its flexibility. Once the equivalent circuit (or the geometric MWS model) has been generated, it can be freely used in the simulation tools. A disadvantage is the need for preparing a working set-up in CST DESIGN STUDIO or CST MWS STUDIO which can be a time-consuming and error prone task.

Convenient Workflow: Integrated Modeling

The workflow uses the 2DTL- or the 3DFEFD-method, but the aim is not to generate an equivalent circuit only, but to provide a complete simulation result. All information on the electric connectivity between pins, net structures and the electrical models of the components are used to establish a complete simulation set-up automatically and without any interaction from the user. The advantage of  this workflow is its efficiency. There different convenient workflow types supports the user:

• SITD (SITD)

• SIFD (SIFD)

• IR-Drop (IR-Drop)

• PIFD (PIFD)

The different workflows will be explained in the following sections.