1. Capacitors and Inductors Instructor: Chia-Ming Tsai Electronics Engineering National Chiao Tung University Hsinchu, Taiwan, R.O.C.

2. Contents Introduction Capacitors Series and Parallel Capacitors Inductors Series and Parallel Inductors Applications

3. Introduction Ideal capacitors and inductors are storage elements that dissipate no energy during operation Both exhibit frequency-dependent characteristics

4. Capacitors A capacitor consists of two conducting plates separated by an insulator (or dielectric) The energy is stored in its electric field

5. Cont’d Types of capacitors –Electrolytic: low-frequency and high-capacitance (10 4  F) applications –Ceramic: high-frequency and small-capacitance (~1pF) applications –Polyester, mica, film, etc Capacitors are used to select RF channel, block dc, pass ac, shift phase, store energy, start motor, and suppress noise

6. Linear Capacitors Slope = C q q vv Linear Nonlinear

7. I-V Characteristic of Capacitor (a) fixed capacitor (b) variable capacitor

8. Power and Energy in Capacitor 0

9. Cont’d v t i t v +_+_ v +_+_ ISIS ISIS ISIS ISIS Charging Discharging ii

10. Properties of Capacitor A capacitor is an open circuit to dc. The voltage on a capacitor cannot change abruptly. Not allowedAllowed

11. Cont’d An ideal capacitor dose not dissipate energy. Capacitors can be used as memory devices –Volatile: DRAM –Nonvolatile: EPROM, Flash, etc The circuit model of a practical capacitor is shown below (100M  ) ()()

12. Example Find energy stored in each capacitor under dc conditions Capacitors replaced by open circuits

13. Parallel Capacitors

14. Series Capacitors

15. Inductors An inductor consists of a coil of conducting wire The energy is stored in its magnetic field

16. I-V Characteristic of Inductor (a) air-core (b) iron-core (c) variable iron-core

17. Power and Energy in Inductor 0

18. Properties of Inductor An inductor acts like a short circuit to dc. The current through an inductor cannot change abruptly. Not allowedAllowed

19. Cont’d An ideal inductor dose not dissipate energy. The circuit model of a practical inductor is shown below : winding capacitance : winding resistance

20. Example

21. Series Inductors

22. Parallel Inductors

23. Summary Parallel connectionsSeries connections

24. Linearity Investigations Homogeneity property: Additivity property: Both exhibit linearity properties

25. Applications: Integrator

26. Alternative Integrator Problem: Large i L due to small L under dc

27. Applications: Differentiator

28. Alternative Differentiator Problem: Large L is difficult to realize