UNIVERSITY EXAMINATIONS: 2018/2019
EXAMINATION FOR THE DEGREE OF BACHELOR OF SCIENCE IN
INFORMATION SECURITY AND FORENSICS
BISF1208 SEMICONDUCTORS AND ELECTRONIC DEVICES
FULL TIME/PART TIME
DATE: DECEMBER, 2018 TIME: 2 HOURS
INSTRUCTIONS: Answer Question One & ANY OTHER TWO questions.
QUESTION ONE
a) Using a suitable diagram describe the structure of semiconductor materials [6 Marks]
b) Describe the main steps in semiconductor fabrication [6 Marks]
c) Give the difference between LEDs and LCDs [2 Marks]
d) Define the terms digital and analogue. [2 Marks]
e) Give three advantages of digital systems [3 Marks]
f) Name the logic gates below and give their truth tables [5 Marks]
g) Define the terms below
i. doping
ii. p-n junction
iii.forward bias
iv.free electrons [4 Marks]
QUESTION TWO
a) List four boolean rules that you can use to minimise a circuit [4 Marks]
b) Briefly describe the principle of operation of the LED [4 Marks]
c) Perform the following number conversions [6 Marks]
i. 94.2710 = _______________8
ii. CB.8E16 = ______________2
iii. 1010010.1010112 = __________8
d) List three applications of digital systems [3 Marks]
e) Name three practical logic circuits that are used in computers processors today [3 Marks]
QUESTION THREE
a) Describe how intrinsic semiconductors can be doped to give N-type material [6 Marks]
b) Using suitable circuit diagrams show the construction and operation of the adder [6 Marks]
c) Give the symbols and truth tables any three logic gates [6 Marks]
d) Name two material used as semiconductors [2 Marks]
QUESTION FOUR
a) Describe the p-n junction, explain both the forward bias and reverse bias [8 Marks]
b) Briefly explain the operation of the following electronic devices [12 Marks]
i. diode
ii. BJT
iii. FET
QUESTION FIVE
a) Given the truth table below, minimise the output using a k-map and give the outputs X and Z.
Draw the circuits. [10 Marks]
b) Give the difference between combinational and sequential logic [3 Marks]
c) Perform the following calculations
i. 10010 -1111
ii. 110010 + 10011
iii. 12(10)-17(10). Use 2s complement subtraction [7 Marks]
