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This document appears to be part of an exam for an electronic circuits course covering transistors. It includes 5 multiple choice questions testing knowledge of transistor terminology and properties. It also includes 6 problems involving calculating currents, voltages, power dissipation, and other transistor parameters in various circuit configurations. The document provides figures to accompany some of the circuit problems.

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Hasnaa Mahmoud
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143 views2 pages

Sheet 1

This document appears to be part of an exam for an electronic circuits course covering transistors. It includes 5 multiple choice questions testing knowledge of transistor terminology and properties. It also includes 6 problems involving calculating currents, voltages, power dissipation, and other transistor parameters in various circuit configurations. The document provides figures to accompany some of the circuit problems.

Uploaded by

Hasnaa Mahmoud
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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Banha University Electronic Circuits

Faculty of Engineering at Shoubra 3rd Year Communications


Electrical Engineering Department (2021 - 2022)

Sheet 1

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Question 1 : Choose the correct answer
1. In a pnp transistor, the p regions are :
a. base and collector b. base and emitter c. emitter and collector
2. For operation as an amplifier, the base of an npn transistor must be
a. positive with respect to the emitter b. positive with respect to the collector
c. negative with respect to the emitter d. 0 V
3. The βDC of a transistor is its :
a. current gain b. voltage gain c. power gain d. internal resistance
4. To saturate a BJT ,
a. IB = IC(sat) b. IB > IC(sat)/βDC
c. VCC must be at least 10 V d. the emitter must be grounded
5. Once in saturation, a further increase in base current will
a. cause the collector current to increase b. not affect the collector current
c. cause the collector current to decrease d. turn the transistor off

Question 2 : Problems
1. Explain the purpose of a thin, lightly doped base region
2. A base current of 50 mA is applied to the transistor in Figure 1, and a voltage of 5 V is
dropped across RC. Determine:
a. the βDC of the transistor
b. the αDC for the transistor
c. Assume that the transistor is replaced with one having a βDC of 200. Determine
IB, IC, IE, and VCE given that VCC 10 V and VBB 3 V.
d. If VCC is increased to 15 V, how much do the currents and VCE change?

figure 1
3. in circuit of Figure 2 Find:
a. VCE, VBE, and VCB
b. whether or not the transistor is saturated
4. Find IB, IE, and IC in Figure 3, αDC = 0.98.

figure 2 figure 3

5. A certain transistor is to be operated at a collector current of 50 mA. How high can


VCE go without exceeding a PD(max) of 1.2 W?
6. The power dissipation derating factor for a certain transistor is 1 mW/°C. The
PD(max) is 0.5 W at 25°C. What is PD(max) at 100°C?

Dr. Sawsan Abdellatif


Eng. Anas Elsayed

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