1. EMLAB 1 기초 회로 이론 2014. 9. 1.

2. EMLAB 2 Contents 1.Basic concepts 2.Resistive circuits 3.Nodal and loop analysis techniques 4.Operational amplifiers 5.Additional analysis techniques 6.Capacitance and inductance 7.First and second order transient circuits

3. EMLAB 3 Super-computer Rack-mount computer motherboard Printed circuit board Circuits for modern electronic systems Example : ATX power supply schematic

4. EMLAB 4 Electronic circuit design flow System concept Functional specification Schematic circuit Schematic simulation BOM (Bill of materials) PCB layout Test and debugging

5. EMLAB 5 Typical electronic components

6. EMLAB 6 Basic concepts

7. EMLAB 7 Charges : electrons, nucleus

8. EMLAB 8 Friction charges

9. EMLAB 9 Electrons “lost” Electrons “gained” Contact Separation Generation of friction charges

10. EMLAB 10 Electrons(-) are absorbed. (+) charges are generated Electrons(-) are generated. (+) charges are absorbed. Generation of charges : battery Electrons are generated via electro-chemical reaction.

11. EMLAB 11 The globe lights up due to the work done by electric current (moving charges). Steady state current (simple DC circuit) Current

12. EMLAB 12 Charge transport : microscopic view Direction of current is defined as that of positive charges by convention. Direction of current

13. EMLAB 13 Current is electric charges in motion, and is defined as the rate of movement of charges passing a given reference plane. In the above figure, current can be measured by counting charges passing through surface S in a unit time. Definition of current

14. EMLAB 14 Positive charges Negative charges Charge transport mechanism: drift current Charges are drifted by electromagnetic waves. E H E H

15. EMLAB 15 Charge transport : diffusion current Positive charges are plenty. Charges in a wire are moved by diffusion and electromagnetic laws. Charge movement by diffusion Negative charges are plenty. Diffusion Diffusion current is due to density gradient independent of charges.

16. EMLAB 16 Electromotive force Electrons are generated via electro-chemical reaction. Chemical battery (reduction) (oxidation)

17. EMLAB 17 AC(alternating current) generator Electromotive force is generated by changing magnetic flux (Faraday’s law).

18. EMLAB 18 Circuit elements

19. EMLAB 19 Independent sourcesDependent sources Circuit symbols resistorcapacitorinductortransformer Ground (GND)

20. EMLAB 20 voltage sources Voltage source Dry cell Lithium ion battery Lead-acid battery Switching power supply DC power supply i-v characteristics

21. EMLAB 21 Analogy between potential energy and voltage level Absolute value of voltage is not important. Only voltage difference has physical meaning.

22. EMLAB 22 Ground (GND) is used to represent voltage reference (0 V), arbitrarily. Ground symbol

23. EMLAB 23 current source current sources

24. EMLAB 24 resistors

25. EMLAB 25 capacitors

26. EMLAB 26 i-v relation of a capacitor

27. EMLAB 27 inductors

28. EMLAB 28 i-v relation of an inductor

29. EMLAB 29 Passive sign convention A circuit element absorbs power when the current flows into the positive terminal. For passive devices, the terminal into which current comes becomes a positive terminal. For independent sources, current flows out of the positive terminal.

30. EMLAB 30 Example Power is absorbed Power is generated

31. EMLAB 31 Power = 0.1 * 1.5 = 0.15W (absorption) 1.5V 0.1A 1.5V -0.1A Power = -0.1 * 1.5 = -0.15W (generation) Example : passive sign convention

32. EMLAB 32 Power Power is defined to be the energy dissipated per unit time.

33. EMLAB 33 The sum of the powers absorbed by all elements in an electrical network is zero. Another statement of this theorem is that the power supplied in a network is exactly equal to the power absorbed. Tellegen’s theorem -36W 54W -18W -36W + 54W -18W = 0

34. EMLAB 34 Given the two diagrams shown in Fig. 1.12, determine whether the element is absorbing or supplying power and how much. Example 1.2 In Fig. 1.12a the power is P=(2 V)(–4 A)=–8 W. Therefore, the element is supplying power. In Fig. 1.12b, the power is P=(2 V)(–2 A)=–4 W. Therefore, the element is supplying power.

35. EMLAB 35 We wish to determine the unknown voltage or current in Fig. 1.13. Example 1.3 In Fig. 1.13a, a power of –20 W indicates that the element is delivering power. Therefore, the current enters the negative terminal (terminal A), and from Eq. (1.3) the voltage is 4 V. Thus, B is the positive terminal, A is the negative terminal, and the voltage between them is 4 V. In Fig 1.13b, a power of ±40 W indicates that the element is absorbing power and, therefore, the current should enter the positive terminal B. The current thus has a value of –8 A, as shown in the figure.

36. EMLAB 36 Determine the power supplied by the dependent sources in Fig. E1.4. (a) Power supplied = 80 W; (b) power supplied = 160 W. Example E1.4

37. EMLAB 37 Example 1.7 Use Tellegen’s theorem to find the current Io in the network in Fig. 1.19. -12 + 6I o - 108 - 30 - 32 + 176 = 0 I o = 1A

38. EMLAB 38 The charge that enters the BOX is shown in Fig. 1.20. Calculate and sketch the current flowing into and the power absorbed by the BOX between 0 and 10 milliseconds. Example 1.8