Real-Life Models

Non-ideal electronic components exhibit parasitic effects. Depending on the usage, they may show a very different behaviour than the ideal ones. More precise models can sometimes be obtained from their manufacturers or vendors. However, first oder approximations exists that can give satisfactory result in many cases. A few of these simple models are presented in this chapter.

Figure 9.14: simple equivalent circuit of a 0603 resistor

A model for a resistor (case 0603) is depicted in figure 9.14. Conclusion:

• useful up to 1GHz
• values around $150\Omega$ are useful up to 10GHz

Figure 9.15: simple equivalent circuit of a 0603 ceramic capacitor

A model for a (ceramic) capacitor (case 0603) is depicted in figure 9.15. Conclusion:

• as coupling capacitor useful wide into GHz band
• as blocking capacitor a via is necessary, i.e. 10nF has resonance at about 50MHz

Figure 9.16: simple equivalent circuit of an electrolyte capacitor

Electrolyte capacitors are quite complicate to model. They also show the biggest differences from sample to sample. Nonetheless, figure 9.16 gives an idea how a model may look like. Conclusion:

• very broad resonance
• useful up to about 10MHz (strongly depending on capacitance)