FACULTY OF ENGINEERING-BIN-SUEF UNIVERSITY
SHEET
1
Department: Electronics and Communications Engineering
Lecturer: Associate Professor Fathy Mohamed Mustafa
Course Title: Analog Electronic Circuits 1
Course Code: ECE-212
BJT
1- For the circuits in figure a, b, c, d, assumes that the transistors have very large
β. Some measurements have been made on these circuits, with the results
indicated in the figure. Find the values of the other labeled voltages and
currents.
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My best wishes
Associate Professor
Dr. Fathy M. Mustafa
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2- Measurements on the circuits of figure a, b, c, produce labeled voltages as
indicated. Find the value of β for each transistor.
3- For each of the circuits shown in figure a, b, c, d, find the emitter, base, and
collector voltages and currents. Use β = 50, but assume independent of current
level.
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My best wishes
Associate Professor
Dr. Fathy M. Mustafa
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4- For the circuit in Fig. P6.49 let VCC = 5 V, RC = 1 KΩ and RB= 20 KΩ. The
BJT has β = 50. Find the value of VBB that result in the transistor operating
(a) In the active mode with VC = 1 V;
(b) At the edge of saturation;
(c) Deep in saturation with βforced = 10.
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My best wishes
Associate Professor
Dr. Fathy M. Mustafa
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5- A single measurement indicates the emitter voltage of the transistor in the
circuit of Fig. 1 to be 1.2 V. Under the assumption that = 0.7 V, what are VB,
IB, IE, IC, VC, β, and α? (Note: Isn’t it surprising what a little measurement
can lead to?).
6- For the transistor shown in Fig. 2, assume α = 1 and V = 0.5 V at the edge of
conduction. What are the values of VE and VC for VB = 0 V? For what value of
VB does the transistor cut off? Saturate? In each case, what values of V E and
VC result?
Figure 1
Figure 2
7- For the circuit shown in figure, find the labeled node voltages for β = 100.
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Associate Professor
Dr. Fathy M. Mustafa
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8- For the circuit shown in figure, draw a complete small-signal equivalent
circuit for the BJT (use α = 0.99). Your circuit should show the values of all
components, including the model parameters. What is the input resistance
Rin? Calculate the overall voltage gain (Vo / VSig).
9- For the common-emitter amplifier shown in figure, let VCC = 15 V, R1 = 27
kΩ, R2 = 15 kΩ, RE = 2.4 kΩ, and RC = 3.9 kΩ. The transistor has β = 100.
Calculate the dc bias current IC. If the amplifier operates between a source
for which Rsig = 2 kΩ and a load of 2 kΩ, replace the transistor with its
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Associate Professor
Dr. Fathy M. Mustafa
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hybrid-π model, and find the values of Rin, and the overall voltage gain Vo /
VSig.
10The amplifier of figure consists of two identical common-emitter
amplifiers connected in cascade. Observe that the input resistance of the
second stage, Rin2, constitutes the load resistance of the first stage.
(a) For VCC = 9 V, R1 = 100 kΩ, R2 = 47 kΩ, RE = 3.9 kΩ, RC = 6.8 kΩ, and β =
100, determine the dc collector current and dc collector voltage of each
transistor.
(b) Draw the small-signal equivalent circuit of the entire amplifier and give
the values of all its components.
(c) Find Rin1 and Vb1 / VSig. for Rsig = 5 kΩ.
(d) Find Rin2 and Vb2 / Vb1.
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My best wishes
Associate Professor
Dr. Fathy M. Mustafa
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11- For the emitter follower in figure, the signal source is directly coupled to the
transistor base. If the dc component of Vsig is zero, find the dc emitter
current. Assume β = 100. Neglecting ro, find Rin, the voltage gain Vo / Vsig, the
current gain Io / Ii.and the output resistance Rout.
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My best wishes
Associate Professor
Dr. Fathy M. Mustafa
10