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The German University in Cairo Electronics 5 Semester
Faculty of Information Engineering & Technology Semiconductors (Elct 503)
Electronics Department Fall 2006
Problem Set 1
1) Write the Volt-Ampere relation for a pn junction and give the significance of each term.
2) Why can the reverse-saturation current be considered a scale factor for diode current
ratings?
3) What is meant by the cut-in voltage?
4) a) Sketch the volt-ampere characteristic of an ideal diode.
b) Explain how this resembles a switch
c) Sketch the volt-ampere characteristic of a practical diode.
5) What is the significance of the load line?
6) What is meant by transfer function?
7)
a) The ammeter reading in the diode circuit shown is 0.1 pA. Determine Is of the diode
given v T =25mV.
D1
A 100k
5V
b) If the battery in the above circuit is reversed, estimate I assuming v y = 0.5 V
and rf =0.
8) In the diode circuit shown, determine the voltmeter reading given that Is =1pA
at 300K and v T =25mV.
1m A
9) Find the current I in the shown circuit [ Vγ =0.6, rf =0]
10) Find the current I in the shown the shown circuit. [ Vγ =0.6V, rf =0]
1k D10 5k
2V 4V
11) Find the current I in the circuit shown. [Vγ = 0.7 and rf = 0].
12) In the diode circuit shown, determine the voltmeter reading V for
a) Switch in position 1
b) Switch in position 2
Assume silicon diodes with Vγ = 0.7 and rf = 0.
D2
D1
13) What do the following circuits imply? (Inputs are either high or low)
5V
Va
R1
Vb
Va
Vc
vo
Vb
R vo
Vc
14)
a) Find the transfer characteristic of the shown circuit.
2k
vi vo
2V
2k
b) Sketch the output signal if the input signal is v i (t)= 6 sin ωt
[Assume ideal switch diodes Vγ = 0 and rf = 0.]
15) For the following circuits, find the transfer function and v o
vo
vi R
vi vo
Vref
Vref
a
b
1k
R
vi vo
vi vo
Vref
Vref
d
c
vi vo
Vref Vref
Vref2 > Vref1
1 2
16) If v s is a sinusoidal signal with 24V peak amplitude;
100
1k
Vs 12V
a) Find the fraction of each cycle during which the diode conducts.
b) Find the peak value of the diode current.
c) Find the max. reverse voltage that appears across the diode.
17) For circuit shown (assume ideal diode)
a) Sketch the output voltage Vo(t).
b) Calculate the average output voltage and current.
R1
1k Vo(t)
Vi(t)
18) Sketch the output voltage Vo(t) and the transfer function for the circuit shown
assuming that the diode is :
a) ideal
b) Represented by Vγ = 0.6 and rf = 0.
200
Vi(t) 200 Vo(t)
19) Obtain the voltage transfer characteristics for the circuit shown assuming
diodes are identical and having Vγ = 0.6 and rf = 0.
D1
15k
D2
7.5k 5k Vo(t)
Vi(t)
20) Find the values of I&V in the circuits shown
21) Calculate Vs if the two diodes operating at room temperature, having
I=0.1mA, η =2 and
a) Is1 = Is2 = 1nA
b) D1: Is1=1nA
D2: Is2=2nA 1k
Vs
D1 D2
-
22) Graphically obtain the operating point in the shown circuit at room temperature
if Is=1nA, η =2
D1
1V 1k
23) Graphically obtain the current I in the resistor at room temperature if both
diodes have Is=1nA, η =2.
1k
0.8V
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