Examination Material for Analogue Electronics Unit - Manchester Metropolitan University, Exams of Electrical Engineering

Download Examination Material for Analogue Electronics Unit - Manchester Metropolitan University and more Exams Electrical Engineering in PDF only on Docsity! S157 24/01/03 THE MANCHESTER METROPOLITAN UNIVERSITY FACULTY OF SCIENCE AND ENGINEERING DEPARTMENT OF ENGINEERING AND TECHNOLOGY SESSION 2002/2003 Examination for the BEng (HONS) ELECTRICAL AND ELECTRONIC ENGINEERING HND ELECTRONIC ENGINEERING YEAR ONE UNIT 64EE1102 : ANALOGUE ELECTRONICS Friday 16 May 2003 9.30 am to 11.30 am Instructions to Candidates Attempt FOUR questions. Marks for each section are shown in parentheses. 1 24/01/03 continued 1. (a) Briefly explain, with the aid of a diagram, the problem of crossover distortion experienced in Class B push-pull amplifiers. [5] (b) (i) Explain, with the aid of a circuit diagram, how the problem of crossover distortion can be overcome using a Class AB amplifier configuration. (ii) Is the Class AB amplifier more or less efficient than a Class B amplifier? Explain your answer. [7] (c) State the maximum theoretical efficiency of a Class B amplifier and a Class A amplifier with a resistive load. [3] (d) For a particular Class B amplifier the dc input power is 50 watts and the efficiency of the amplifier is 60%. The maximum junction temperature of the power transistors is 200 degrees Centigrade and θJC = 2 deg C/W. Determine the maximum thermal resistance of a suitable heatsink, assuming both output power transistors are mounted on the same heatsink and the maximum ambient temperature is 30 degrees Centigrade. [10] 4 24/01/03 continued 4. (a) (i) Explain briefly, (including appropriate diagrams) the operation of an ENHANCEMENT mode MOSFET. [5] (ii) Integrated MOSFET electrical characteristics can be designed by variations in manufacturing process technology and MOSFET layout geometry. State using appropriate equations and explain using diagrams and script : - The meaning and significance of the commonly used terms β, W and L and the ratio W/L. [10] (b) For ONE of the following, write an essay describing: (i) the operation and manufacture of the MOSFET; (ii) the circuit topology and operation of MOSFET, tri-state binary logic. [10] 5 S157 24/01/03 5. Figure Q5 depicts the trajectories of 6 holes within a vertical, silicon, PNP Bipolar Junction Transistor. Figure Q5 (© Milward 1955) (i) State what is meant by carrier ‘recombination’. [2] (ii) State how base width changes BJT operation. [3] (iii) State why there is a depression seen in the ‘surface’ around the base terminal. [2] (iv) State what is occurring when the base region is energised to the potential depicted by the letters A & B. [2] (v) Sketch an electronic circuit schematic that could provide these bias conditions. [2] (vi) Labelling the holes shown, (from left to right), numbers 1 -> 6; state, creating a table to help in your explanation, the electrical conditions that gave rise to the paths illustrated for holes 1, 2, 4 and 5. [12] (vii) If the transistor were manufactured from germanium instead of silicon, explain how appearance of Figure Q5 might change. [2] END