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Electronics · 2nd Puc Science

Ch 2Transistor Biasing — 2nd PUC Electronics, concept-first.

A transistor (BJT) whose terminals are not connected to any kind of voltage source is called an unbiased transistor. In this state the device does nothing useful, so an unbiased transistor is never used in actual practice.

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Key concepts

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DC Load Line

The DC load line is a straight line on the transistor's output characteristics showing every possible pair of collector current and collector-to-emitter voltage under no-signal conditions.

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Chapter contents

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Introduction

A transistor (BJT) whose terminals are not connected to any kind of voltage source is called an unbiased transistor.

2.1

DC Load Line, Q Point and Transistor Biasing Methods

- setting (IC = 0) gives the X-axis (cutoff) point (VCE(cutoff) = VCC); - setting (VCE = 0) gives the Y-axis (saturation) point (IC(sat) = VCC/RC).

Chapter Summary

This chapter explained how a bipolar junction transistor is set up for use. An unbiased transistor is of no practical use; applying a suitable DC voltage — transistor biasing — fixes the DC currents a…

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+Show 5 questions5 questions
  1. Example 1Illustration 1: Find the end points of the load line for the circuit given (figure 2.1.4). ![Figure 2.1.4 is a CE-mode npn transistor fixed-…Free
  2. Example 2Illustration 2: Compare the load lines for the two circuits of figure 2.1.6a and figure 2.1.6b. ![Two CE-mode npn biasing circuits driven fr…Free
  3. Example 3Find the end points of the load line for the circuit given figure 2.1.11. ![Figure 2.1.11 is a voltage divider bias circuit with an npn tran…Preview
  4. Example 4Find the Q point for the circuit of figure 2.1.11 considering transistor to be of silicon. ![Figure 2.1.11 is a voltage divider bias circuit…Preview
  5. Example 5Draw the load line and estimate the values of Q point of voltage divider bias circuit, if V_CC = 12 V, R_E = 1 kΩ, R_1 = 40 kΩ, R_2 = 5 kΩ a…Preview
+Show 15 questions15 questions
  1. Q1What is biasing of a transistor?Free
  2. Q2Why is the transistor called as current controlled device?Free
  3. Q3What is an unbiased transistor?Free
  4. Q4Define quiescent point.Preview
  5. Q5What is meant by dc load line?Preview
  6. Q6What is thermal runaway?Preview
  7. Q7Define stabilization of a transistor.Preview
  8. Q8Mention any one factor on which stabilization depends.Preview
  9. Q9Name any one parameter of the transistor which is temperature dependent.Preview
  10. Q10What is leakage current?Preview
  11. Q11Mention any one leakage current in a transistor.Preview
  12. Q12Name any one biasing circuit.Preview
  13. Q13Name the biasing circuit which gives excellent stabilization.Preview
  14. Q14What is heat sink?Preview
  15. Q15Write the relation between I_CEO and I_CBO.Preview
+Show 12 questions12 questions
  1. Q1Explain biasing of a transistor.Free
  2. Q2Draw DC load line and mark the end points.Free
  3. Q3What are quiescent point and load line?Free
  4. Q4Mention any two biasing circuits.Preview
  5. Q5Why is the voltage divider bias circuit preferred in the amplification process?Preview
  6. Q6What are the advantages of voltage divider bias?Preview
  7. Q7What is the significance of a load line?Preview
  8. Q8What is leakage current? Mention different types of leakage currents.Preview
  9. Q9Explain collector-to base leakage current and collector-to- emitter leakage current.Preview
  10. Q10What is thermal runaway? Explain.Preview
  11. Q11On what factors does stabilization of a transistor depend on?Preview
  12. Q12What is meant by heat sink? Mention its importance.Preview
+Show 10 questions10 questions
  1. Q1What is an unbiased transistor? Explain the need for biasing the transistor.Free
  2. Q2Describe the steps to draw the dc load line for a transistor.Free
  3. Q3What is a Q point ? Explain its significance.Free
  4. Q4What is voltage divider bias? Mention its advantages.Preview
  5. Q5Explain the steps required to draw the dc load line for voltage divider bias circuit.Preview
  6. Q6Derive the equations to determine the coordinates for Q point in voltage bias circuit.Preview
  7. Q7Explain collector-to base leakage current and collector-to- emitter leakage current.Preview
  8. Q8What is meant by stabilization? Mention the parameters which affect the stabilization.Preview
  9. Q9Name the different biasing circuits. Which biasing circuit is better recommended to get faithful amplification?Preview
  10. Q10Explain the terms thermal runaway, leakage current and heat sink.Preview
+Show 5 questions5 questions
  1. Q1What is an unbiased transistor? Mention different types of biasing a transistor.Free
  2. Q2What is voltage divider bias? Derive the coordinates to draw the load line of voltage divider bias.Free
  3. Q3Derive the expressions for the Q point in voltage divider bias.Preview
  4. Q4Explain i) Stabilization of Q point. ii) Selection of Q points on the load line. iii) Thermal runaway. iv) Heat sink. v) Leakage currents.Preview
  5. Q5How does stabilisation takes place in voltage divider bias? Explain.Preview