2022-11-13 15:50 Status: # Modelling Components Capacitors have series lead inductance and internal inductance as well as resistive losses caused by the finite conductivity of the dielectric material. Since losses are usually quite small in capacitors, they can often be modeled as series LC circuits. A [Capacitor](../Microelectronics/Capacitor.md) will therefore have a series resonant frequency above which the impedance will be inductive. Resistors of low value and appreciable lead length appear as series RL circuits. Higher value resistors in the range of at least 100 Ω are better modeled as parallel RC circuits. An RLC model for a resistor can be used when required by the modeled behavior. Lead inductance is often a dominant parasitic when the component impedance magnitude is not particularly large. A good rule-of-thumb to remember is that 1 mm of lead length has approximately 1 nH of inductance. Chapter 3 of the ECE 453 Course Notes goes into more detail. Inductors often come in one of two configurations: solenoid and toroid. The solenoid can have an air core, while the toroid is usually wound around a donut-shaped core, which increases inductance and confines the magnetic field better. A significant parasitic effect in inductors is capacitance between its coils. It leads to a parallel resonant frequency as discussed in Chapter 3 of the course notes. The [parallel resonance](parallel%20resonance.md) depends on the construction of the [inductor](inductor.md). In addition, inductors wound on a core material will be subject to dielectric loss in the core material which can be modeled as parallel resistance. [^1] --- # References [^1]: [Lab2_ModelingDiscreteComponents.pdf (illinois.edu)](https://courses.engr.illinois.edu/ece453/sp2019/lab_files/Lab2_ModelingDiscreteComponents.pdf)