Bjt biasing pyq yearwise

Related Concepts: bjt biasing pyq theory | Bjt biasing book references | Bjt biasing types

Based on the sources provided, here are all the past year questions (PYQs) that pertain to the topics covered in Chapter 4: DC Biasing—BJTs (such as load-line analysis, operating point/Q-point, various bias configurations, design operations, transistor switching networks, and bias stabilization/thermal runaway).

Year 2023

• 1. a) Define load line and explain it’s significance. Explain the effect of changing the circuit elements of a fixed bias common emitter circuit on the transistor operating point.
• 2. a) Define thermal stability in transistor amplifiers. Explain thermal runway and how it can be prevented using bias stabilization techniques.
• 2. c) Determine $R_C$, $R_E$ and $R_B$ for the emitter bias configuration of shown in figure 2(c). (Includes Figure 2(c))

Year 2022

• 1. a) What is meant by thermal runaway? How does thermal runaway change the operating point of an amplifier?
• 1. c) Explain the factors that affect the stability of a transistor circuit.
• 1. d) Given that $I_{CQ}=2$ mA and $V_{CEQ}=10$ V, determine $R_1$ and $R_C$ for the network of Fig. 1(d). (Includes Figure 1(d))

Year 2021

• 1. a) Explain the effect of changing the levels of base current, collector resistance and $V_{CC}$ on the transistor operating point (Q) using the load line analysis.
• 1. b) Explain the factors that affect the stability of a transistor circuit. How does an additional emitter resistance improve the stability? Explain in brief considering the physical happenings.
• 1. d) Determine the levels of $R_C$, $R_E$, $R_1$ and $R_2$ for the network of Fig. 1(d) for the operating point indicated. (Includes Figure 1(d))
• 2. a) Describe the concept of mid-point biasing.

Year 2020

• 1. a) How can a transistor be used as a switch?
• 1. b) Design a voltage-divider bias network using a supply of 24V, a transistor with a beta of 110 and operating point of $I_{CQ}=4$ mA and $V_{C{E}_Q}=8$V. Choose $V_E=1/8V_{CC}$.

Year 2019

• 1. c) Determine the levels $R_C$, $R_E$, $R_1$ and $R_2$ for the network in Fig. 1(c) with the operating point of $I_{CQ}=10$ mA and $V_{CEQ}=8$ V. (Includes Figure 1(c))
• 1. d) What do you mean by bias stabilization and thermal runway?

Year 2018

• 1. a) What is the necessity of transistor biasing? Design a fixed bias circuit in order to obtain the following load line and Q-point. (Includes Figure 1(a))
• 1. b) How is the operating point of transistor affected by increase of surrounding temperature?
• 1. c) Write the mathematical expressions of stability factors and hence show that voltage divider bias configuration is the most stable.
• 1. d) What is the condition for approximate analysis of voltage divider bias configuration? Determine the values of $I_{CQ}$ and $V_{CEQ}$ of the following network using approximate analysis. (Includes Figure 1(d))

Year 2017

• 1. a) What is load line? Explain the effects of changing the levels of base current, collector resistance, and $V_{cc}$ on the transistor operating point (Q) using the load line analysis.
• 1. b) Explain the factors that affect the stability of a transistor circuit. How does an additional emitter resistance improve the stability? Explain in brief considering the physical happenings.
• 1. c) How can you design an inverter switch using bipolar junction transistor?
• 1. d) Determine the quiescent levels of $I_{CQ}$ and $V_{CEQ}$ for the following network shown in figure 1(d). (Includes Figure 1(d))

Year 2016

• 1. a) What is the necessity of biasing a transistor? Design a fixed bias circuit in order to obtain the following load line and Q-point. (Includes Figure 1(a))
• 1. b) What is meant by bias stabilization? “The Q-point of a bias circuit become more stable if an emitter resistance is connected”- Justify the statement.
• 1. c) Write down the necessary conditions for a transistor to work as an amplifier or switch.
• 1. d) Determine $R_1$ and $R_C$ for the following voltage divider network with the operating point of $I_{CQ}=2$mA and $(V_{CE}{)}_Q=10$V. (Includes Figure 1(d))

Year 2015

• 1. a) What is load line analysis? Explain the switching operation of BJT using load line analysis.
• 1. b) What do you mean by bias stabilization and thermal runway? Explain in brief.
• 1. c) Write the mathematical expressions of stability factors and hence show that voltage divider bias configuration is most stable.
• 1. d) Determine the values of $I_{CQ}$ and $V_{CEQ}$ for the voltage divider configuration of Fig. 1(d). (Includes Figure 1(d))