Introduction to active and passive components

This presentation is for beginners of electronics. This will give you a brief about all the important basic building blocks of electronics and hence will be helpful in creating a good foundation.

1. Introduction to Electronic Components -Deependra Goswami

2. Electronic Component : Electronic component is basic fundamental building block of any electronic system precisely used to affect electrons and their associated fields. Each component may have one or more basic properties and it behaves accordingly.

3. Classification of Electronic Components

4. Active Components Active components are those which conduct upon providing some external energy i.e. require electrical power to operate. Usually they inject power into the circuit. Examples – Diodes, Transister, ICs, Transformer etc.

5. DIODES Diode is a one way valve for electricity. It is a two terminal semiconductor device, these two terminals are called the anode and cathode. It lets the electricity to flow only in one direction.

6. Most diodes have painted line on one end showing the direction or flow. The negative side is normally white Current flow through diode only when positive voltage is applied to anode and negative voltage is connected to cathode If these voltages are reversed, then the current will not flow.

7. DIODE V-I CHARACTERSTICS

8. VARIOUS TYPES OF DIODE

9. LIGHT EMITTING DIODE (LED) This is one of the most popular diodes used in our daily life. This is also a normal PN junction diode except instead of silicone and germanium, the materials like gallium arsenide, gallium arsenide phosphide used in construction.

10. Structure Of LED

11. WORKING PRINCIPLE OF LED Like a normal PN junction diode, this is connected in forward bias condition so that the diode conducts. The conduction takes place in a LED when the free electrons in the conduction band combine with the holes in the valence band. This process of recombination emits  light . This process is called as  Electroluminescence .

12. The color of the light emitted depends upon the gap between the energy bands. The materials used also effect the colors like, gallium arsenide phosphide emits either red or yellow, gallium phosphide emits either red or green and gallium nitrate emits blue light. Whereas gallium arsenide emits infrared light. The LEDs for non-visible Infrared light are used mostly in remote controls.

13. TRANSISTOR A transistor is a 3 three terminal semiconductor device in which a voltage is applied to one of the terminal (called base) can control current that flows across the other two terminals (called collector and base). These 3 terminals are called Emitter, Base and Collector

14. It is a fundamental building block of circuitory in mobile phones, computers, and several other electronic devices. Transistor has very fast response and is used in number of functions including voltage regulations, amplification, switching, oscillators etc. Transistors may be packed individually or they can be a part of an IC (integrated circuit). Some of the ICs have billions of transistors ia very small area.

15. TYPES OF TRANSISTORS NPN : When a P-type semiconductor is sandwitched between two N-type semiconductor then it is called NPN. Majority charge carriers are electrons. PNP : When a N-type semiconductor is sandwitched between two P-type semiconductor then it is called NPN. Majority charge carriers are holes.

16. FIELD EFFECT TRANSISTORS (FET) The FET is a transistor that uses a electric field to control the electrical behaviour of device. FETs are also known as unipolar transistors since they involve single carrier type operation. The device consist of an active channel through which charge carriers, electrons or holes flow from source to drain. The conductivity of channel is function of potential applied across the gate and source terminals.

17. FET’s 3 terminals are : 1. Source(S), through which the carriers enter the channel. Conventionally, the current entering the channel is designated by Is. 2. Drain(D), through which the carriers leave the channel. Conventionally, the current entering the drain is designated by I D . Drain to source voltage is V DS. 3. Gate(G), the terminal that modulates the channel conductivity. By applying voltage to G one can control I D.

18. TYPES OF FETs The JFET: Junction field effect transistor The MOSFET: Metal oxide semiconductor field effect transistor The MNOS: Metal nitride oxide semiconductor transistor The DGMOSFET: Dual gate MOSFET The MODFET: Modulation doped FET The TFET: Tunnel field effect Transistor etc.

19. MOSFET MOSFET stands for Metal Oxide Silicon Field Effect Transistor or Metal Oxide Semiconductor Field Effect Transistor. This is also called as IGFET meaning Insulated Gate Field Effect Transistor. The FET is operated in both depletion and enhancement modes of operation.

20. The following figure shows how a practical MOSFET looks like.

21. CONSTRUCTION OF MOSFET The construction of a MOSFET is a bit similar to the JFET. An oxide layer is deposited on the substrate to which the gate terminal is connected. This oxide layer acts as an insulator (sio 2  insulates from the substrate), and hence the MOSFET has another name as IGFET (Insulated gate FET). With negative gate bias voltage, it acts as  depletion MOSFET  while with positive gate bias voltage it acts as an  Enhancement MOSFET .

22. The following figure shows the construction of a MOSFET.

23. The voltage at gate controls the operation of the MOSFET. In this case, both positive and negative voltages can be applied on the gate as it is insulated from the channel. In the construction of MOSFET, a lightly doped substrate, is diffused with a heavily doped region. Depending upon the substrate used, they are called as  P-type  and  N-type  MOSFETs.

24. CLASSIFICATION OF MOSFET Depending upon the type of materials used in the construction, and the type of operation, the MOSFETs are classified as in the following figure.

25. Let us consider an N-channel MOSFET to understand its working. A lightly doped P-type substrate is taken into which two heavily doped N-type regions are diffused, which act as source and drain. Between these two N+ regions, there occurs diffusion to form an N-channel, connecting drain and source. A thin layer of  Silicon dioxide (SiO 2 )  is grown over the entire surface and holes are made to draw ohmic contacts for drain and source terminals. N-MOSFET

26. STRUCTURE OF N-MOSFET

27. A conducting layer of  aluminum  is laid over the entire channel, upon this  SiO 2 layer from source to drain which constitutes the gate. The  SiO 2  substrate  is connected to the common or ground terminals. Because of its construction, the MOSFET has a very less chip area than BJT, which is 5% of the occupancy when compared to bipolar junction transistor. This device can be operated in modes. They are depletion and enhancement modes.

28. Working of N - Channel (depletion mode) MOSFET For now, we have an idea that there is no PN junction present between gate and channel in this, unlike a FET.

29. We can also observe that, the diffused channel N (between two N+ regions), the  insulating dielectric SiO 2  and the aluminum metal layer of the gate together form a  parallel plate capacitor . If the NMOS has to be worked in depletion mode, the gate terminal should be at negative potential while drain is at positive potential. When no voltage is applied between gate and source, some current flows due to the voltage between drain and source. Let some negative voltage is applied at  V GG . Then the minority carriers i.e. holes, get attracted and settle near  SiO 2  layer. But the majority carriers, i.e., electrons get repelled.

30. With some amount of negative potential at  V GG  a certain amount of drain current  I D  flows through source to drain.  When this negative potential is further increased, the electrons get depleted and the current  I D  decreases. Hence the more negative the applied  V GG , the lesser the value of drain current  I D  will be. The channel nearer to drain gets more depleted than at source (like in FET) and the current flow decreases due to this effect. Hence it is called as depletion mode MOSFET.

31. Working of N - Channel (Enhancement mode) MOSFET The same MOSFET can be worked in enhancement mode, if we can change the polarities of the voltage  V GG . So, let us consider the MOSFET with gate source voltage  V GG  being positive as shown in the following figure.

32. When no voltage is applied between gate and source, some current flows due to the voltage between drain and source. Let some positive voltage is applied at  V GG . Then the minority carriers i.e. holes, get repelled and the majority carriers i.e. electrons gets attracted towards the  SiO 2  layer. With some amount of positive potential at  V GG  a certain amount of drain current  I D  flows through source to drain. When this positive potential is further increased, the current  I D  increases due to the flow of electrons from source and these are pushed further due to the voltage applied at  V GG . Hence the more positive the applied  V GG , the more the value of drain current  I D  will be. The current flow gets enhanced due to the increase in electron flow better than in depletion mode. Hence this mode is termed as  Enhanced Mode MOSFET .

33. Hence the more positive the applied  V GG , the more the value of drain current  I D  will be. The current flow gets enhanced due to the increase in electron flow better than in depletion mode. Hence this mode is termed as  Enhanced Mode MOSFET .

34. P-MOSFET The construction and working of a PMOS is same as NMOS. A lightly doped  n-substrate  is taken into which two heavily doped  P+ regions  are diffused. These two P+ regions act as source and drain. A thin layer of  SiO 2  is grown over the surface. Holes are cut through this layer to make contacts with P+ regions, as shown in the following figure.

35. STRUCTURE OF P-MOSFET

36. The drain characteristics of a MOSFET are drawn between the drain current  I D and the drain source voltage  V DS . The characteristic curve is as shown below for different values of inputs. DRAIN CHARACTERSTICS

37. Transfer characteristics define the change in the value of  V DS  with the change in  I D  and  V GS  in both depletion and enhancement modes. The below transfer characteristic curve is drawn for drain current versus gate to source voltage. TRANSFER CHARACTERSTICS

38. OP-AMP (IC-741) An operational amplifier is a direct-coupled high-gain amplifier. It offers the gain of the order of 10 6. Op-Amp IC-741 +V CC -V EE output Noninverting input Inverting input - +

39. An operational amplifier is available as a single integrated circuit package. There are 8 pins in it, 7 pins are active, 4 pins are for excitation/input, 1 pin is not used hence named IC-741. It usually consisting of one or more differential amplifiers and followed by a level translator and an output stage. It is a versatile device that an amplify DC as well as AC. PIN DIAGRAM

40. IDEAL OP-AMP CHARACTERSTICS Infinite voltage gain. Infinite input resistance so that almost any signal source can drive it and there is no loading on the preceding stage. Zero output resistance so that output can drive an infinite number of other devices. Infinite bandwidth so that any frequency signal from 0 to ∞ Hz can be amplified without attenuation. Infinite CMRR so that the output common-mode noise voltage is zero. Infinite slew rate so that output voltage changes occur simultaneously with input voltage changes.

41. Equivalent Circuit of Op-Amp Vo = Ad (V1-V2) = AdVd The op-amp amplifies the difference between the two input voltages. It does not amplify the input voltages themselves. The polarity of the output voltage depends on the polarity of the difference voltage Vd.

42. Ideal Voltage Transfer Characteristics

43. Internal Circuit Of Op-Amp INPUT STAGE INTERMEDIATE STAGE LEVEL SHIFTING STAGE OUTPUT STAGE NON INVERTING I/P INVERTING I/P DUAL I/P BALANCED O/P DIFFERENTIAL AMPLIFIER DUAL I/P UNBALANCED O/P DIFFERENTIAL AMPLIFIER EMITTER FOLLOWER CIRCUIT USING CONSTANT CURRENT SOURCE DUAL I/P BALANCED O/P DIFFERENTIAL AMPLIFIER O/P

44. Continued.... The input stage is the dual input balanced output differential amplifier. This stage generally provides most of the voltage gain of the amplifier and also establishes the input resistance of the op-amp. The intermediate stage is usually another differential amplifier, which is driven by the output of the first stage. On most amplifiers, the intermediate stage is dual input, unbalanced output. Because of direct coupling, the dc voltage at the output of the intermediate stage is well above ground potential. Therefore, the level translator (shifting) circuit is used after the intermediate stage downwards to zero volts with respect to ground. The final stage is usually a push pull complementary symmetry amplifier output stage. The output stage increases the Voltage swing and raises the ground supplying capabilities of the op-amp. A well designed Output stage also provides low output resistance.

45. APPLICATIONS It was originally designed for computing such mathematical functions as addition, subtraction, multiplication, and integration. Thus the name operational amplifier stems from its original use for these mathematical operations and is abbreviated to op-amp. With the addition of suitable external feedback components, the modern day op-amp can be used for a variety of applications, such as ac and dc signal amplification, active filters, oscillators, comparators, regulators, and others.

46. INSTRUMENTATION AMPLIFIER Its one of the important application is in construction of instrumentation amplifier . In many industrial and consumer applications the measurement and control of physical conditions are very important. For e.g. measurements of temperature and humidity inside a dairy or meat plant permit the operator to make necessary adjustments to maintain product quality. Similarly, precise temperature control of plastic furnace is needed to produce a particular type of plastic.

47. CIRCUIT DIAGRAM OF INSTRUMENTATION APMLIFIER

48. APPLICATION INPUT STAGE INTERMEDIATE STAGE OUTPUT STAGE Quantity to be measured Transducer + Preamplifier Instrumentation Amplifier Indicator and automatic process controller Transmssion line O/P

49. Continued … Some transducers produce outputs with sufficient strength to perform their use directly, many do not. To amplify the low-level output signal of the transducer so that it can drive the indicator or display is the major function of the instrumentation amplifier. The instrumentation amplifier is intended for precise, low-level signal amplification where low noise, low thermal and time drifts, high input resistance, and accurate closed-loop gain are required. Besides, low power consumption, high common-mode rejection ratio, and high slew rate are desirable for superior performance.

50. TIMER (IC-555) IC 555 was Introduced in 1970 by SIGNATICS corporation. It is used for generation of square wave (asymmetric and symmetric), saw tooth, and various other applications such as Astable, Monostable, and Bistable multivibrator. The most versatile linear integrated circuits is the 555 timer.

51. The 555 is a monolithic timing circuit that can produce accurate and highly stable time delays or oscillation. The device is available as an 8-pin metal can, an 8-pin mini DIP. The timer basically operates in one of the two modes: either as monostable (one-shot) multivibrator or as an astable (free running) multivibrator. The important features of the 555 timer are these: it operates on +5 to + 18 V supply voltage in both free-running (astable) and one- shot (monostable) modes; it has an adjustable duty cycle; timing is from microseconds through hours; it has a high current output; it can source or sink 200 mA. A sample of these applications includes mono-stable and astable multivibrators, dc-dc converters, digital logic probes, waveform generators, analog frequency meters and tachometers, temperature measurement and control, infrared transmitters, burglar and toxic gas alarms, voltage regulators, electric eyes, and many others.

52. PIN DIAGRAM

53. FUNCTIONAL BLOCK DIAGRAM OF 555 TIMER 2/3 V cc 1/3 V cc

54. PIN DESCRIPTION AND WORKING Pin 1: Ground All voltages are measured with respect to this terminal. Pin 2: Trigger The output of the timer depends on the amplitude of the external trigger pulse applied to this pin. The output is low if the voltage at this pin is greater than 2/3 VCC. However, when a negative-going pulse of amplitude larger than 1/3 VCC is applied to this pin, the comparator 2 output goes low, which in turn switches the output of the timer high. The output remains high as long as the trigger terminal is held at a low voltage.

55. Pin 3: Output There are two ways a load can be connected to the output terminal: either between pin 3 and ground (pin 1) or between pin 3 and supply voltage +V CC (pin 8). When the output is low, the load current flows through the load connected between pin 3 and +V CC into the terminal and is called the sink current. However, the current through the grounded load is zero when the output is low. For this reason, the load connected between pin 3 and +V CC is called the normally on load and that connected between pin 3 and ground is called the normally off load. On the other hand, when the output is high, the current through the load connected between pin 3and + VCC (normally on load) is zero. However, the output terminal supplies current to the normally off load. This current is called the source current. The maximum value of sink or source current is 200 mA.

56. Pin 4: Reset. The 555 timer can be reset (disabled) by applying a negative pulse to this pin. When the reset function is not in use, the reset terminal should be connected to + VCC to avoid any possibility of false triggering. Pin 5: Control voltage An external voltage applied to this terminal changes the threshold as well as the trigger voltage . In other words, by imposing a voltage on this pin or by connecting a pot between this pin and ground, the pulse width of the output waveform can be varied. When not used, the control pin should be bypassed to ground with a 0.01-μF capacitor to prevent any noise problems.

57. Pin 6: Threshold This is the non-inverting input terminal of comparator 1, which monitors the voltage across the external capacitor. When the voltage at this pin is threshold voltage 2/3 V, the output of comparator 1 goes high, which in turn switches the output of the timer low. Pin 7: Discharge This pin is connected internally to the collector of transistor, When the output is high, Transistor is off and acts as an open circuit to the external capacitor C connected across it. On the other hand, when the output is low, Q1 is saturated and acts as a short circuit, shorting out the external capacitor C to ground. Pin 8: + VCC The supply voltage of +5 V to +18 is applied to this pin with respect to ground (pin 1).

58. EQUIVALENT CIRCUIT OF 555 TIMER

59. Passive Components Passive electronic components are those that don’t have the ability to control current by means of another signal. They start their operation once they are connected. No external energy is needed for their operation. E.g. Resistors, capacitors, inductors, LDR etc.

60. RESISTOR It is device that resists the flow of current. Resistors comes in variety of resistance values(how much they resist current, measured in unit called ohm) and power rating (how much power they can handle without burning up, measured in watts).

61. RESISTOR SYMBOL

62. POTENTIOMETER A potentiometer is a 3 terminal resistor with a sliding or rotating contact that forms an adjustable voltage divider. If only two terminals are used, one end and the wiper, it act as a variable resistor

63. LIGHT DEPENDENT RESISTOR (LDR) An LDR is a component that has a (variable) resistance that change with the light intensity that falls upon it. This allows them to be used in light sensing circuits.

64. CAPACITOR It is a device that can temporarily store an electric charge. Capacitors come in several varieties, the two most common being ceramic disk and electrolyte. The amount of capacitance of a given capacitor is usually measured in micro farads, uf.

65. INDUCTOR An inductor is also called a coil, choke, or reactor, is a passive two terminal electrical component that stores energy in form of magnetic field when electric current flows through it. An inductor typically consists of an insulated wire wound into a coil around a core.

66. CAPACITOR SYMBOL VARIOUS TYPES OF CAPACITORS

67. LOGIC GATES Logic gates are the basic building blocks of any digital system. It is an electronic circuit having one or more than one input and only one output.  At any given moment, every terminal is in one of the two binary conditions  low  (0) or  high  (1), represented by different voltage levels. The relationship between the input and the output is based on a  certain logic . Based on this, There are 7 different logic gates : AND, OR, NOT, NAND, NOR, XOR, XNOR etc.

68. AND GATE A circuit which performs an AND operation is shown in figure. It has n input (n >= 2) and one output. Logic diagram: Truth table:

69. OR GATE A circuit which performs an OR operation is shown in figure. It has n input (n >= 2) and one output. Logic diagram: Truth table:

70. NOT GATE NOT gate is also known as  Inverter . It has one input A and one output Y. Logic diagram: Truth table:

71. NAND GATE A NOT-AND operation is known as NAND operation. It has n input (n >= 2) and one output. Logic diagram: Truth table:

72. NOR GATE A NOT-OR operation is known as NOR operation. It has n input (n >= 2) and one output. Logic diagram: Truth table:

73. XOR GATE XOR or Ex-OR or exclusive-OR gate is a special type of gate. It can be used in the half adder, full adder and subtractor. It has n input (n >= 2) and one output. Logic diagram: Truth table:

74. XNOR GATE XNOR or EX- NOR or exclusive-NOR gate is a special type of gate. It can be used in the half adder, full adder and subtractor. It has n input (n >= 2) and one output. Logic diagram: Truth table:

75. DC TO DC BOOSTER CIRCUIT OR BOOST CONVERTER A process that changes one DC voltage to a different DC voltage is called DC to DC conversion. A boost converter is a DC to DC converter with output voltage greater than the source voltage. A boost converter is sometimes called step-up converter since it “steps-up” the source voltage. DC to DC boosters are available as ICs requiring few more components and are also available as complete hybrid circuit modules, ready for use with in a electronic assembly.

76. THE BASIC SCHEMATIC OF DC TO DC BOOST CONVERTER

77. Thank you