As illustrated with the transformer equivalent circuit, transformers have numerous parasitic properties, which can have a negative effect on the signal. In this chapter it is therefore explained why and where one applies transformers. An additional section deals with the requirements for signal transformers. To conclude the chapter, some standard commercially available transformers are described. 3.1 Function and application areas of transformers As a...

SMD NiZn Ferrite Core Storage Choke SMD storage chokes with highly dynamic and low loss NiZn ferrite cores (such as Würth Elektronik WE-PD series) are suitable as chokes in switching control applications up to a clock frequency of approx. 10MHz and offer high current loading capacity and low DC resistances. There are a multitude of construction types available for the different types of application:...

2.3 Power Inductors and Calculations Switched-mode power supplies are becoming ever more widespread. The semiconductor manufacturers have made their contribution, offering a wide range these integrated circuits with simplified circuit design. Care must be taken in the selection of the appropriate storage choke to fully utilize the advantages of switching regulators. The selection of cores and windings of storage chokes are optimized for use...

2.2 Current compensated chokes Saturation effects caused by high signal currents, or DC current super imposed on the signal, reduce the effectiveness of the choke. The use of standard inductors in the signal path adversely impairs the useful signal. Current compensation circumvents these disadvantages. In current compensation, the “useful return current” must be passed through the choke. In this way, the useful current does...

2.1 Coil with ferrite inductors SMD-Multilayer Inductor If the wire windings on the outside of a conventional “coil” are mounted inside the coil body, the so-called multilayer SMD inductor (Figure 2.32) is created. Fig. 2.32: SMD-Multilayer inductor; image source: Würth Elektronik WE-MI Fig. 2.33: Structural schematics of multilayer SMD inductors The ferrite body magnetically shields the component, significantly reducing external interference and cross-talk. The...