1. Analogue Electronics 电子 2＋2 Prof. Li Chen
School of Electronics and Information Technology
Sun Yat-sen University
中山大学 电子与信息工程学院 陈立 教授
Tel:
Office: 631C, SEIT Building

2. Analogue Electronics 电子 2＋2
Course Agenda:
* Optional content, compulsory otherwise.
Lecture notes:
Textbooks: [1] R. L. Boylestad and L. Nashelsky, Electronic Devices and Circuit Theory, Pearson Education, 2007, ISBN [2] 高玉良, 电路与模拟电子技术, 高教出版社, 2004, ISBN
Chapters
Schedule (weeks)
CH1 Basic Concepts and Circuit Analysis
1 – 2
CH2 Semiconductor Diodes
3 – 5
CH3 Bipolar Junction Transistors (BJTs)
6 – 8
CH4 Field Effect Transistors (FETs)
9 – 11
CH5 Operational Amplifiers
12 – 14
CH6 Feedback Circuits
15 – 16
CH7 AC and DC Converters * 17

3. Chapter 1 - Basic Concepts and Circuit Analysis
1.1 Basic Concepts and Electric Circuits
1.2 Circuit Elements
1.3 Kirchhoff's Current and Voltage Laws
1.4 Thevenin and Norton Theorems
1.5 Frequency Spectrum

4. 1.1 Basic Concepts and Electric Circuits
Current
Amount of electric charges flowing through the surface per unit time.
Constant current
Time rate of change of charge
Time varying current
Unit
(1 A = 1 C/s)
Notation: Current flow represents the flow of positive charge
Alternating versus direct current (AC vs DC)
i(t) t DC AC
Time – varying current
Steady current

5. 1.1 Basic Concepts and Electric Circuits
Current
Positive versus negative current
2 A
-2 A
Negative charge of -2C/s moving
Positive charge of 2C/s moving or
Negative charge of -2C/s moving
Positive charge of 2C/s moving or
P1.1, In the wire electrons moving left to right to create a current of 1 mA. Determine I1 and I2.
Ans: I1 = -1 mA; I2 = +1 mA.
Current is always associated with arrows (directions)

6. 1.1 Basic Concepts and Electric Circuits
Voltage (Potential)
Energy per unit charge.
It is an electrical force drives an electric current.
Voltage
Units: 1 V = 1 J/C
Positive versus negative voltage + –
2 V
-2 V

7. 1.1 Basic Concepts and Electric Circuits
Voltage (Potential)
Example  a b
a、b, which point’s potential is higher？  b a
Vab = ? a b
+Q from point b to point a get energy ，Point a is Positive? or negative ?  

8. 1.1 Basic Concepts and Electric Circuits
Voltage (Potential) a b c´ c d d´
Example I

9. 1.1 Basic Concepts and Electric Circuits
Voltage (Potential)
Example
Va = ?
K Open I
K Close I

10. 1.1 Basic Concepts and Electric Circuits
Example I I

11. 1.1 Basic Concepts and Electric Circuits
Power
One joules of energy is expanded per second.
P = W/t
Rate of change of energy + –
v(t)
i(t)
p(t) = v(t) i(t)
v(t) is defined as the voltage with
positive reference at the same
terminal that the current i(t) is entering.
Used to determine the electrical power is being absorbed or supplied
if P is positive (+), power is absorbed
if P is negative (–), power is supplied

12. 1.1 Basic Concepts and Electric Circuits
Power
Example 2A + –
-5V
Power is supplied. delivered power to external element. + – 5V 2A
Power is absorbed. Power delivered to
Note : + –
+5V
-5V 2A
-2A
Power is absorbed

13. 1.1 Basic Concepts and Electric Circuits
Power
Power absorbed by a resistor:
Note: In circuit analysis, p(t) is often referred as the instantaneous power at time t, while P as the average power over a certain period.

14. 1.1 Basic Concepts and Electric Circuits
Power
Find the power absorbed by each element in the circuit. 1 2 3 4 5 I1 I2 I3 + - + - - + + -
Supply energy : element 1、3、4 .
Absorb energy : element 2、5

15. 1.1 Basic Concepts and Electric Circuits
Open Circuit
R=
I=0, V=E , P=0 E R0
Short Circuit
R=0 E R0
R＝0

16. 1.1 Basic Concepts and Electric Circuits
Loaded Circuit E R0 R I

17. 1.2 Circuit Elements Passive elements (cannot generate energy)
e.g., resistors, capacitors, inductors, etc.
Active elements (capable of generating energy)
batteries, generators, etc.
Important active elements
Independent voltage source
Independent current source
Dependent voltage source
voltage dependent and current dependent
Dependent current source

18. 1.2 Circuit Elements Resistors Dissipation Elements v=iR
P=vi=Ri2=v2/R >0 ，
v-i relationship v i
Resistors connected in series:
Equivalent Resistance is found by Req= R1 + R2 + R3 + … R1 R2 R3
Resistors connected in parallel 1/Req=1/R1 + 1/R2 + 1/R3 + … R1 R2 R3

19. 1.2 Circuit Elements Capacitors
Capacitance occurs when two conductors (plates) are separated by a dielectric (insulator).
Charge on the two conductors creates an electric field that stores energy.
The voltage difference between the two conductors is proportional to the charge: q = C v
The proportionality constant C is called capacitance.
Units of Farads (F) - C/V
1F= one coulomb of charge of each conductor causes a voltage of one volt across the device.
1F=106F, 1F=106PF

20. 1.2 Circuit Elements Capacitors store energy in an electric field+ -
v(t)
The
rest of
the
circuit
v-i relationship
vC(t+) = vC(t-)
Energy stored
Capacitors connected in series:
Equivalent capacitance is found by 1/Ceq=1/C1 + 1/C2 + 1/C3 + …
series
parallel
Capacitors connected in parallel Ceq= C1 + C2 + C3 + …

21. 1.2 Circuit Elements Capacitors For (1) : i(t) + 0.2F v(t) - i(t) 1A

22. 1.2 Circuit Elements Capacitors For (2) : For (1)、(2) : i(t) + 0.2F-
v(t)
0.2F
For (2) :
For (1)、(2) : t
i(t) 1A
-1A 1s 2s t
w (t)
2.5J 1s 2s
(2)

23. 1.2 Circuit Elements Inductors
store energy in a magnetic field that is created by electric passing through it.
v-i relationship
i(t) + -
v(t) L
iL(t+) = iL(t-)
Energy stored:
Inductors connected in series: Leq= L1 + L2 + L3 + …
Inductors connected in parallel: 1/Leq=1/L1 + 1/L2 + 1/L3 + …

24. Independent voltage source
1.2 Circuit Elements
Independent voltage source
RS＝0 + VS v i VS
Ideal
practical

25. 1.2 Circuit Elements Voltage source connected in series:
Voltage source connected in parallel:

26. 1.2 Circuit Elements
Voltage controlled (dependent) voltage source (VCVS) + _
Current controlled (dependent) voltage source (CCVS) + _

27. 1.2 Circuit Elements
Voltage controlled (dependent) current source (VCCS) _ +
Current controlled (dependent) current source (CCCS)

28. 1.2 Circuit Elements Independent source dependent source
Can provide power to the circuit;
Excitation to circuit ;
Output is not controlled by external.
dependent source
Can provide power to the circuit;
No excitation to circuit;
Output is controlled by external.

29. 1.2 Circuit Elements Review
So far, we have talked about two kinds of circuit elements:
Sources (independent and dependent)
active, can provide power to the circuit.
Resistors
passive, can only dissipate power.
The energy supplied by the active elements is equivalent to the energy absorbed by the passive elements!

30. 1.3 Kirchhoff's Current and Voltage Laws
Nodes, Branches, Loops, mesh
Node: point where two or more elements are joined (e.g., big node 1)
Branch: Component connected between two nodes (e.g., component R4)
Loop: A closed path that never goes twice over a node (e.g., the blue line)
Mesh: A loop that does not contain any other loops in it.

31. 1.3 Kirchhoff's Current and Voltage Laws
Nodes, Branches, Loops, mesh
A circuit containing three nodes and five branches.
Node 1 is redrawn to look like two nodes; it is still one nodes.

32. 1.3 Kirchhoff's Current and Voltage Laws
KCL
sum of all currents entering a node is zero
sum of currents entering node is equal to sum of currents leaving node

33. 1.3 Kirchhoff's Current and Voltage Laws
KCL
KCL-Christmas Lights + -
120V
50* 1W Bulbs Is
Find currents through each light bulb:
IB = 1W/120V = 8.3mA
Apply KCL to the top node:
IS - 50IB = 0
Solve for IS: IS = 50 IB = 417mA

34. 1.3 Kirchhoff's Current and Voltage Laws
KCL
Supernode: for the sake of analysis, two nodes can be merged into a supernode by ignoring the current in between.
Node 2
Node 3

35. 1.3 Kirchhoff's Current and Voltage Laws
KVL
sum of voltages around any loop in a circuit is zero.
KVL Mathematically
A voltage encountered + to - is positive.
A voltage encountered - to + is negative.

36. 1.3 Kirchhoff's Current and Voltage Laws
KVL
KVL is a conservation of energy principle
A positive charge gains electrical energy as it moves to a point with higher voltage and releases electrical energy if it moves to a point with lower voltage
If the charge comes back to the same Initial point the net energy gain Must be zero.

37. 1.3 Kirchhoff's Current and Voltage Laws
KVL
P1.13
Determine the voltages Vae and Vec.
Vec = 0

38. 1.3 Kirchhoff's Current and Voltage Laws
KVL
Voltage divider + + R1 V1 N - V + R2 V2 - -
Important voltage Divider equations

39. 1.3 Kirchhoff's Current and Voltage Laws
KVL
Voltage divider
P1.14
Example: Vs = 9V, R1 = 90kΩ, R2 = 30kΩ
Volume control?

40. Circuit Theory Review: Voltage Division
1.3 Kirchhoff's Current and Voltage Laws
Circuit Theory Review: Voltage Division
and
Applying KVL to the loop,
and
Combining these yields the basic voltage division formula:

41. Circuit Theory Review: Voltage Division
1.3 Kirchhoff's Current and Voltage Laws
Circuit Theory Review: Voltage Division
Using the derived equations with the indicated values,

42. Circuit Theory Review: Current Division
1.3 Kirchhoff's Current and Voltage Laws
Circuit Theory Review: Current Division
where
Combining and solving for vs,
Combining these yields the basic current division formula:

43. Circuit Theory Review: Current Division
1.3 Kirchhoff's Current and Voltage Laws
Circuit Theory Review: Current Division
Using the derived equations with the indicated values,

44. 1.4 Thevenin and Norton Theorems
Thevenin Theorem
Any linear electrical network with voltage and current sources and only resistances can be replaced at terminals A-B by an equivalent voltage source Vth in series connection with an equivalent resistance Rth
This equivalent voltage Vth is the voltage obtained at terminals A-B of the network with terminals A-B open circuited.
This equivalent resistance Rth is the resistance obtained at terminals A-B of the network with all its independent current sources open circuited and all its independent voltage sources short circuited.

45. 1.4 Thevenin and Norton Theorems
Determine the Thévenin Equivalent Voltage
Applying KCL to the upper node,
Applying KVL to the outer loop,
Combine the above equations,

46. 1.4 Thevenin and Norton Theorems
Determine the Thévenin Equivalent Resistance
Applying KCL,

47. 1.4 Thevenin and Norton Theorems
Any linear electrical network with voltage and current sources and only resistances can be replaced at terminals A-B by an equivalent current source In in parallel connection with an equivalent resistance Rth.
This equivalent current In is the current obtained at terminals A-B of the network with terminals A-B short circuited.
This equivalent resistance Rth is the resistance obtained at terminals A-B of the network with all its independent voltage sources short circuited and all its independent current sources open circuited

48. 1.4 Thevenin and Norton Theorems
Determine the Norton Equivalent Circuit
Applying KCL,
Short circuit at the output causes zero current to flow through RS.
Rth is equal to Rth found earlier.

49. 1.4 Thevenin and Norton Theorems
Thévenin and Norton equivalent Circuits
Check of Results: Note that vth = inRth and this can be used to check the calculations: inRth=(2.55 mS)vs(282 ) = 0.719vs, accurate within round-off error.
While the two circuits are identical in terms of voltages and currents at the output terminals, there is one difference between the two circuits. With no load connected, the Norton circuit still dissipates power!

50. Frequency Spectrum of Electronic Signals
Non repetitive signals have continuous spectra often occupying a broad range of frequencies
Fourier theory tells us that repetitive signals are composed of a set of sinusoidal signals with distinct amplitude, frequency and phase.
The set of sinusoidal signals is known as a Fourier series.
The frequency spectrum of a signal is the amplitude and phase components of the signal versus frequency.

51. Frequency Spectrum of Electronic Signals
Any periodic signal can be expressed by Fourier series as
- angular frequency of the signal in rad/sec

52. Frequency Spectrum of Electronic Signals

53. Frequency Spectrum of Electronic Signals
Audible sounds 20 Hz - 20 KHz
Baseband TV MHz
FM Radio MHz
Television (Channels 2-6) MHz
Television (Channels 7-13) MHz
Maritime and Govt. Comm MHz
Cell phones MHz
Satellite TV GHz

54. Frequency Spectrum of Electronic Signals
Any periodic signal contains spectral components only at discrete frequencies related to the period of the original signal.
A square wave is represented by the following Fourier series:
0 = 2/T (rad/s) is the fundamental radian frequency and f0=1/T (Hz) is the fundamental frequency of the signal. 2f0, 3f0, 4f0 and called the second, third and fourth harmonic frequencies.