Transistor Bipolar - Komponen Elektronika

Salah satu komponen yang digunakan di Rangkaian Listrik, yaitu Transistor Bipolar. Slide ini menjelaskan Transistor Bipolar secara keseluruhan, dari simbol hingga aplikadi penguat.

1. Bipolar Transistor Instructor: yunita Program Studi Teknologi Rekayasa Sistem Elektronika (TRSE)

2. Introduction – to Transistors What is a Transistor? Semiconductor device used to amplify or switch electronic signals Fundamental building block in electronic devices Types of Transistors Bipolar Junction Transistors (BJTs) Field-Effect Transistors (FETs) Focus on BJTs Emphasis on BJTs, including structures, operation, and applications. 11/15/2024 Komponen Elektronika 2

3. Semiconductor Device Used to Amplify or Switch Electronic Signals A transistor is a small, three-terminal semiconductor device that can control and amplify electrical currents or act as an electronic switch. It works by controlling the flow of electric charge carriers (electrons and holes) through its layers, allowing it to modulate or switch currents in a circuit. Transistors enable precise control of current and voltage, making them essential in signal processing and digital switching. 11/15/2024 Komponen Elektronika 3

4. Fundamental Building Block in Electronic Devices Transistors are foundational elements in virtually all modern electronics, including computers, smartphones, and audio systems. Introduced in the 1940s, transistors replaced vacuum tubes, making devices smaller, faster, and more energy-efficient. Their versatility allows them to be used in a wide range of applications, from analog amplifiers to digital logic circuits. By integrating millions (or billions) of a transistor on a single chip, we can create complex processors and memory devices that drive the functionality of modern technology. 11/15/2024 Komponen Elektronika 4

5. Types of Transistors Bipolar Junction Transistors (BJTs): Uses both electrons and holes for charge transport. Commonly used in amplifiers and switching circuits. Field Effect Transistors (FETs): Controls current using an electric field. Widely used in digital electronics due to their high efficiency and fast switching speeds. 11/15/2024 Komponen Elektronika 5

6. Transistor Structure Basic Structure of a BJT Constructed with three doped semiconductor region separated by two pn junctions Consists of three layers: Emitter, Base, and Collector Two main types: NPN and PNP transistors. Diode Junctions BJTs has two junctions: Base-Emitter and Base-Collector Standard BJT Symbols 11/15/2024 Komponen Elektronika 6

7. Structure and Layers Emitter (E): Heavily doped to inject a large number of charge carriers (electrons in an NPN transistor and holes in a PNP transistor). Base (B): Thin and lightly doped, allowing most charge carriers from the Emitter to pass through to the Collector. Collector (C): Moderately doped and designed to collect carriers from the Emitter, enabling large current flow. 11/15/2024 Komponen Elektronika 7

8. Basic Transistor Operation How a BJT Works Current flow from Emitter to Collector is controlled by Base current Current Amplification Small input current at Base controls larger current from Collector to Emitter Modes of Operation Active Mode: Amplification (Base-Emitter forward biased, Collector-Base reverse-biased) Saturation Mode: Acts as a closed switch Cutoff Mode: Acts as an open switch 11/15/2024 Komponen Elektronika 8

9. Basic Operation Principles – In a NPN BJT A small Base current ( ) flows into the Base, causing a larger Collector current ( ) to flow from the Collector to the Emitter. The Base-Emitter junction is forward-biased (positive voltage applied to Base relative to Emitter), allowing electrons to move from the Emitter to the Base. The Base-Collector junction is reverse-biased (Collector is at a higher positive voltage than Base), which helps “pull” electrons from the Base into the Collector region.   11/15/2024 Sample Footer Text 9

10. Basic Operation Principles – In a PNP BJT The operation is similar but with opposite charge carriers (holes) and voltage polarities. The Base-Emitter junction is forward-biased, allowing holes to move from the Emitter to the Base. The Base-Collector junction is reverse-biased, pulling holes from the Base into the Collector. 11/15/2024 Sample Footer Text 10

11. Transistor Characteristics and Parameters Current Gain ( ) or DC Beta ( ) Ratio of Collector current ( ) to Base current ( ) Typical values range from 20 to 1000 Input and Output Characteristics Input Characteristics: Relationship between Base-Emitter voltage and Base current Output Characteristics: Relationship between Collector-Emitter voltage and Collector current Other Parameters ( ) : Base-Emitter voltage (usually around 0.7V for silicon BJTs). ( ) (sat): Collector-Emitter saturation voltage h-parameters ( ) : Hybrid parameters used in AC analysis; ( = )   11/15/2024 Komponen Elektronika 11

12. BJT Transistor Currents Three main currents: Emitter Current ( ), Base Current ( ), and Collector Current ( ). In NPN and PNP Transistor: Current flow directions differ based on the type   11/15/2024 Sample Footer Text 12

13. BJT Transistor Currents - Emitter Current ( )   Definition: The total current flowing out of (for NPN) or into (for PNP) the Emitter Supplies charge carriers (electrons for NPN, holes for PNP) to the Base and Collector. In an NPN transistor, ( ) is the sum of electrons injected into the Base and those reaching the Collector. Emitter current is typically the largest of the three currents in BJT   11/15/2024 Sample Footer Text 13

14. BJT Transistor Currents - Base Current ( )   Definition: The small current flowing into (for NPN) or out of (for PNP) the Base Controls the larger Collector-Emitter current and enables the transistor’s amplification ability is a small fraction of , usually around 1% to 5% Determines the transistor’s current gain ( ) Current Gain Relationship:   11/15/2024 Sample Footer Text 14

15. BJT Transistor Currents - Collector Current ( )   Definition: The current flowing into (for NPN) or out of (for PNP) the Collector Controlled by the Base current and usually represents the main current in the BJT depends on and the current gain ( ) of the transistor. Used for amplification; provides larger output current relative to the small input current Relationship with Base Current:   11/15/2024 Sample Footer Text 15

16. BJT Transistor Currents - Collector Current ( )   The ratio of the dc Collector current ( ) to the dc Emitter current ( ) is the dc alpha ( ) The alpha is less-used parameter than beta in transistor circuits. Typically, values of range from 0.95 to 0.99 or greater, but is always less than 1. The reason is that is always slightly less than by the amount of . For example, if and , then and =0.99   11/15/2024 Sample Footer Text 16

17. Current Relationship in a BJT Kirchoff’s Current Law (KCL) Applied to BJTs: The total current entering the transistor is equal to the total current leaving. Equation: In NPN transistors: Electrons flow from Emitter to Collector In PNP transistors: Holes flow from Emitter to Collector.   11/15/2024 Sample Footer Text 17

18. Exercises Given Parameters Assume and Find and   11/15/2024 Komponen Elektronika 18

19. Transistor DC Bias Circuits forward-biases the Base-Emitter junction reverse-biases the Base-Collector junction In practice: the voltages are often derived from a dc power supply. is normally taken directly from the power supply output and (which is smaller) can be produced with a voltage divider   11/15/2024 Sample Footer Text 19

20. Current and Voltage Analysis 11/15/2024 Sample Footer Text 20

21. Current and Voltage Analysis forward-biases the Base-Emitter junction, reverse-biases the Base-Collector junction. When the Base-Emitter junction is forward-biased, it is like a forward-biased diode and has a nominal forward voltage drop of Since the Emitter is at ground (0 V), by Kirchoff’s voltage law, the voltage across is Also, by Ohm’s law,   11/15/2024 Sample Footer Text 21

22. Current and Voltage Analysis The voltage at the Collector with respect to th e grounded Emitter is Since the drop across is Where The voltage across the reverse-biased Collector-Base junction is   11/15/2024 Sample Footer Text 22

23. Example 11/15/2024 Sample Footer Text 23

24. Solution 11/15/2024 Sample Footer Text 24

25. Exercise 11/15/2024 Sample Footer Text 25

26. Collector Characteristic Curves Collector characteristic curves represent the relationship between the Collector-Emitter Voltage ( ) and the Collector Current ( ) at various values of Base Current ( ) . X-Axis ( ): Represents the Collector-Emitter Voltage. This is the voltage applied across the Collector and Emitter terminals. Y-Axis ( ): Represents the Collector Current. This is the main current flowing from the Collector to the Emitter in an NPN transistor (or Emitter to Collector in a PNP transistor). Family of Curves (for different values): Each curve corresponds to a specific Base Current ( ). By changing the Base current, we can observe how the Collector current responds to different values.   11/15/2024 Sample Footer Text 26

27. Collector Characteristic Curves 11/15/2024 Sample Footer Text 27

28. Key Regions on the Collector Characteristic Curves Cutoff Region In this region, (no Base current), so there is no Collector current ( ≈ 0). The transistor behaves as if it is off, similar to an open switch. The curve is near zero current despite changes in .   11/15/2024 Sample Footer Text 28

29. Key Regions on the Collector Characteristic Curves Active Region Here, is proportional to and relatively independent of ( ≈ β × ). The BJT operates as an amplifier in this region, where a small change in Base current leads to a large change in Collector current. Each curve remains fairly horizontal, indicating that changes only slightly with increases in once it is past a certain threshold (about 0.7V for silicon BJTs). This is the ideal region for analog signal amplification.   11/15/2024 Sample Footer Text 29

30. Key Regions on the Collector Characteristic Curves Saturation Region When is very low (typically below 0.3V for an NPN BJT), the transistor enters saturation. In saturation, both the Base-Emitter and Base-Collector junctions are forward-biased. no longer follows β × because the Collector current has reached its maximum limit for a given , and further increases in have little effect on . The transistor behaves like a closed switch with maximum current flow.   11/15/2024 Sample Footer Text 30

31. DC Load Line The DC Load Line is a graphical representation of all the possible values of Collector current ( ) and Collector-Emitter voltage ( ) for a given circuit when no input signal is applied. It is derived from the Collector-Emitter circuit of the BJT and shows how the output voltage ( ) changes as the output current ( ) varies due to a fixed load resistor ( ) and supply voltage ( ). The load line intersects the transistor's output characteristic curves ( vs. curves for different base currents, ) at different points, representing the possible states of the transistor, including cutoff, active, and saturation regions.   11/15/2024 Sample Footer Text 31

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33. How to Derive the DC Load Line This equation is the equation of a straight line, where: is the y-intercept, is the x-intercept, and is the slope of the line (negative, as an increase in reduces ).   11/15/2024 Sample Footer Text 33

34. Steps to Plot the DC Load Line Determine the x-intercept ( max): This occurs when (the Collector and Emitter are shorted). Set to 0 in the equation: This gives the maximum Collector current ( max) that would flow if the transistor were in saturation (fully on).   11/15/2024 Sample Footer Text 34

35. Steps to Plot the DC Load Line Determine the y-intercept ( max): This occurs when (no current flows through the Collector). Set to 0 in the equation: This is the maximum possible voltage across the Collector and Emitter if the transistor is in cutoff (fully off).   11/15/2024 Sample Footer Text 35

36. Steps to Plot the DC Load Line Plot the DC Load Line: Mark max on the axis (y-axis). Mark max on the axis (x-axis). Draw a straight line between these two points. This is the DC Load Line.   11/15/2024 Sample Footer Text 36

37. Steps to Plot the DC Load Line Interpreting the DC Load Line Once the DC Load Line is plotted, it intersects the BJT characteristic curves for different values of Base current ( ). Each point on this line represents a possible operating point for the BJT under the given load conditions. Cutoff Region: The point on the load line where ≈ 0 and ≈ . The transistor behaves as if it is off, with minimal current flow. Saturation Region: The point on the load line where ≈ 0 and ≈ max. The transistor behaves as if it is fully on, with maximum current flowing. Active Region: The part of the load line between cutoff and saturation where the transistor can function as an amplifier. In this region, and is between its minimum (near 0) and maximum ( ) values.   11/15/2024 Sample Footer Text 37

38. Example 11/15/2024 Sample Footer Text 38

39. Example-Solution 11/15/2024 Sample Footer Text 39

40. Exercise 11/15/2024 Sample Footer Text 40

41. Metode Pembiasan pada transistor Pembiasan Tujuan Pembiasan Jenis Pembiasan

42. 1. Bias Basis Sumber tegangan V BB memberi bias maju pada dioda emitor melalui R B Sumber tegangan V CC memberikan tegangan ke kaki kolektor emitor melalui R C Sehingga I B = (V BB -V BE )/R B Karena I C = β DC . I B Sehingga tegangan kolektor-emitor menjadi V CE = V CC – I C .R C

43. 2. Bias Umpan Balik Kolektor Merupakan upaya perbaikan dari bias basis Resistor basis dihubungkan ke kolektor Tujuannya adalah untuk mendapatkan titik kerja transistor ( titik Q) yang lebih stabil

44. Persamaan garis bebannya adalah I C = (V CC – V CE )/R C Sedangkan persamaan untuk menentukan arus kolektor adalah I C = (V CC – V BE )/(R C + R B / β DC )

45. Contoh 3 : Transistor 2N3904 memiliki β DC yang berubah dari 100 sampai dengan 300. Dengan menggunakan bias umpan balik kolektor seperti pada gambar di bawah, hitunglah arus kolektor minimum dan maksimumnya !

46. 3. Bias Pembagi tegangan Rangkaian pembagi tegangan dibentuk oleh R 1 dan R 2 . Biasanya tegangan yang ada di R 2 dinamakan sebagai tegangan thevenin V TH = (R 2 /(R 1 +R 2 )).V CC V TH = V B V E = V B – V BE = V B – 0,7V Dengan demikian I E = V E /R E Arus emitor nilainya hampir sama dengan arus kolektor , sehingga I E ≈ I C V C = V CC – I C .R C V CE = V C - V E

47. Contoh 4 : Tentukan VB, VE, IE, IC dan VCE dari rangkaian pada gambar di bawah ini !

48. 4. Bias Emitor Merupakan cara pembiasan yang sangat stabil Biasanya menggunakan sumber tegangan positif dan negatif Paling banyak digunakan dalam IC Untuk transistor NPN tegangan emitor kira-kira -1V yaitu sedikit tegangan melintas R B ditambah dengan tegangan jatuh dioda emitor (0,7V). Arus emitor dihitung dengan menggunakan hukum ohm pada resistansi emitor Pendekatan I C ≈ I E masih tetap digunakan untuk menghitung tegangan kolektor yaitu : I E = I C = (V EE – 1V)/R E Sehingga V C = V CC – I C .R C

49. Contoh : Untuk rangkaian bias emitor di bawah ini , tentukan V E , I E , I C dan V CE !

50. The Transistor as a Switch Switching Behavior of BJTs In Cutoff Mode, BJT is off (no current flow). In Saturation Mode, BJT is on (maximum current flow). Application in Digital Electronics Used in logic gates and other digital circuits. Rapid switching allows for high-speed operations in digital systems 11/17/2024 Komponen Elektronika 50

51. Transistor sebagai sakelar

52. Transistor sebagai sakelar Contoh : Untuk rangkaian di samping ini , berapakah VCE pada saat VIN = 0 ? Jika β = 200 dan VCE(sat) = 0, berapakah arus basis minimum yang membuat transistor jenuh ( saturasi ) ? Jika tegangan input 5V, berapakah nilai RB maksimum agar transistor menjadi saturasi ?

53. The Transistor as an Amplifier How Amplification Works A small signal at the Base is amplified at the Collector Types of Amplifiers Using BJTs Common Emitter (CE): Voltage gain and phase inversion Common Base (CB) : Voltage gain without phase inversion Common Collector (CC): Buffer amplifier with high input impedance Applications Audio amplification, signal processing, RF amplifiers 11/15/2024 Komponen Elektronika 53

54. Transistor sebagai penguat Penguat Common Emitter Merupakan jenis penguat transistor yang paling banyak digunakan . Untuk menganalisisnya digunakan dua macam sumber tegangan yaitu tegangan DC (VCC) dan tegangan AC ( sumber sinyal ). 11/17/2024 Sample Footer Text 54

55. Transistor sebagai penguat – Analisa DC

56. Transistor sebagai penguat – Analisa AC Rout = RC

57. Summary Recap of Key Points Structure and types of BJTs (NPN, PNP). How BJTs operate and their modes of operation Characteristics and parameters of BJTs BJTs as amplifiers and switches in electronic circuits. Conclusion BJTs remain essential components in modern electronics for their versatility in amplification and switching applications. 11/15/2024 Komponen Elektronika 57

58. TERIMA KASIH