Cork Institute of Technology
Higher Certificate in Engineering in Electronic Engineering – Stage 1
(NFQ Level 6)
Summer 2006
Analogue Electronics
(Time: 3 Hours)
Answer Question 1 [40 marks] and any
three other questions [each 20 marks]
Examiners: Mr. M. O’Gorman
Mr. D. O’Mahony
Mr. J. Berry
Dr. R. O Dubhghaill
1. (a) Explain why the output voltage of a common emitter transistor amplifier is
180° out of phase with the input voltage. [5 marks]
(b) Explain the term dynamic resistance when applied to a forward-biased diode. [5 marks]
(c) Sketch typical output characteristics for a common emitter transistor and
illustrate the region where the transistor is said to be saturated.
What bias condition exists at the collector-base junction (VCB) when a transistor
operates in the saturated region? [5 marks]
(d) Ignoring any forward voltage dropped across the diodes, calculate the value of
V in the circuit below; [5 marks]
+12V -12V
-6 V
+30 V
V
(e) What is meant by donor doping and acceptor doping?
Explain how the conductivity of a semiconductor material may be improved by
either of the above processes. [5 marks]
(f) Draw a sketch of the electromagnetic spectrum showing the main regions into
which electromagnetic waves of different frequencies are allocated. [5 marks]
(g) Sketch a plot to show how the amplitude of the saturation current through a
reverse-biased diode varies with temperature.
Give a brief explanation. [5 marks]
(h) Briefly explain what is meant by the frequency spectrum of a complex signal.
Sketch the frequency spectrum of a square wave. [5 marks]
