May 2006

Custom data for circuit simulation

S-parameters at the click of a mouse

Today, computer-aided design is much more than the creation of circuit diagrams and layouts with CAD-based programs. Simulation and verification have now advanced to become pre-eminent tasks within the development of electronic circuits. This is the only way of implementing increasingly complex circuits within ever shorter time frames.

Simulation allows the assessment of a circuit with no real samples. However, the quality of the simulation depends strongly on the accuracy of the simulation models used to describe the behavior of the relevant components.

The information specified in the data sheets for the required components is rarely sufficient to set up circuit simulations. It merely supplies the characteristic data for resistors, inductors and capacitors, but does not describe their typical behavior exhaustively.

EPCOS also offers SPICE models of its inductors for all usual simulation tools. They allow the developer to examine the circuit properties precisely under many framework conditions and thus to speed up the development process and make it more reliable.

S-parameters for simulation

EPCOS additionally offers its customers a service that allows them to call up S-parameter sets matched to their requirements in a targeted way. Customers can enter the framework conditions for the simulation of the EPCOS components in their circuit and EPCOS generates optimized S-parameters by using existing SPICE models and sends them to the customer via e-mail.

The customers can then use this data directly in their own simulation tools. The advantage against the S-parameters offered elsewhere is that the customer can use the Internet to specify a series of key data, such as the impedance or frequency range, to define the requisite S-parameters. The simulation therefore supplies much more exact results than the S-parameters otherwise specified on the market for 50Ω systems.

FIGURE 1: INPUT MASK

Input mask for customized S-parameters on the EPCOS home page.

The routine from specific customer inquiry to obtaining the simulation data via e-mail is as simple as can be imagined: The customer selects the component whose operation he wishes to have simulated from a form on the EPCOS website (Fig. 1). He is supported by a database in which all products are stored with their ordering numbers and descriptions. He then adds his contact data – at least his name and e-mail address. Finally, he defines the frequency range, the start and end frequency and the input and output impedance of the test circuit and selects a linear or logarithmic scale of the values. He receives an immediate confirmation via the website.

EPCOS now calculates the S-parameters for the required component with the aid of simulation software by using the entered data and the SPICE model. Within a short time the customer receives the data as an attachment via e-mail.

Further extension of the simulation data

EPCOS currently offers SPICE models and customized S-parameters for SMT inductors and data-line chokes; model libraries for power chokes and EMC filters will follow. EPCOS is also working on making complete libraries available for additional simulation tools. Customized S-parameters are also being planned for products of the other EPCOS divisions. The aim is to make all data relevant to the simulation tasks available to the customer as far as possible in ready-to-use form.

 SPICE AND S-PARAMETERS
SPICE (Simulation Program with Integrated Circuit Emphasis) is software designed to simulate the behavior of electronic circuits. It represents the basis for the simulation software currently in common use in the electrical and electronics industry and allows the behavior of components in a circuit to be determined. S-parameters describe the RF behavior of components, in an equivalent way to a measurement, but depend strongly on the circuit environment.

Authors:

Wolfgang Sammet, Head of Development and Application, Inductors

Stefan Schefler, Simulation Engineer, Inductors

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