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THE MANCHESTER METROPOLITAN UNIVERSITY
FACULTY OF SCIENCE AND ENGINEERING
DEPARTMENT OF ENGINEERING AND TECHNOLOGY
SESSION 2005/
Examination for the BEng (HONS) ELECTRICAL AND ELECTRONIC ENGINEERING HND ELECTRONIC ENGINEERING YEAR ONE
UNIT 64EE1102 : ANALOGUE ELECTRONICS
Tuesday 2 May 2006
2:00 pm to 4:00 pm
Instructions to Candidates
Attempt FOUR questions.
Marks for each section are shown in parentheses.
Candidates are permitted to use their own calculators subject to Faculty Board Examination Procedures and Practices.
S125 11/07/
- (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]
- (a) Define the following terms as applied to an operational amplifier:
(i) input bias current;
(ii) slew rate;
(iii) output voltage range;
(iv) input resistance. [8]
(b) The operational amplifier in the circuit of Figure Q3 is ideal in all respects. Derive an expression for the overall voltage gain Vo/Vin , of the circuit in terms of the resistances R 1 and R 2. Hence find the required value of R 1 and R 2 given that the input resistance of the circuit is to be 1kΩ and the voltage gain –120. [17]
R 2 R 2
R 1
R 1
Vin V
Figure Q
- (a) Integrated MOSFET electrical characteristics can be designed by variations in manufacturing process parameters and MOSFET layout geometry.
For each of the following MOSFET Ids vs Vds output characteristic regions :
o The cut-off region o The linear region o The saturation region.
Explain the electronic operation of an ENHANCEMENT mode MOSFET.
(Your explanation should include both appropriate cross-sectional diagrams and equations that incorporate the commonly used
terms β , W and L .)
[10]
(b) For ONE of the following, write an essay describing in detail:
(i) A complete mains derived power supply unit incorporating mains switch and filter, mains fuse, bridge rectifier full-wave rectification, filter, 78 series 12 volt supply regulator. [8]
How important is the use of a heatsink for the rectifiers or series regulator? [2]
(ii) The circuit topology and operation of MOSFET, tri-state binary logic. [10]
