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TH E MANCH ESTER M ETR O PO LITAN UNIVER SITY
FACULTY O F SCIENCE AND ENGINEER ING
D EPA R TMENT O F ENGINEER ING AND TECH NO LO GY
SESSIO N 2000/
Exam ination for th e BEng (H O NS) ELECTR ICA LAND ELECTR O NIC ENGINEER ING (PA R T TIME) BEng (H O NS) ELECTR O NIC ENGINEER ING (PA R T TIME) YEA R O NE
UNIT 64EE2027/64EE2028 : ELECTR ICALENGINEER ING ANALYSIS/
ANALO GUE ELECTR O NICS
Th ursday 24 May 2001
2.00 pm to 4.00 pm
Instructions to Candidates
A ttem pt TW O questions from each section.
It is recom m ended th at you spend an h our on each section.
SECTIO N A
- (a) Th e circuit of a com m on em itter am plifier is sh ow n in Figure Q 1. If th e quiescent voltages at th e em itter and collector are 2V and 10V respectively, calculate th e follow ing but do not use NPV (nearest preferred values):
(i) th e value of R 3 assum ing IE=IC; [2]
(ii) suitab le values for R 1 and R 2 assum ing h (^) FE(MIN)=200 and VBE=0.7V for th e transistor; [4]
(iii) a new value of R 3 to ob tain m axim um output sw ing. [4]
(b ) R 2 is now rem oved from th e circuit and R 1 is replaced by a 2MΩ resistor. Using th e originalvalue for R 3 found in (a) ab ove, calculate th e quiescent voltages at th e collector and em itter assum ing h (^) FE=300 and VBE=0.7V. Briefly explain w h y th is circuit is less desirab le th an th e original. [15]
Figure Q 1
- (a) Nam e th ree properties of an idealoperationalam plifier. [6]
(b ) Explain w h at is m eant by th e term ‘virtualearth ’w h en applied to an operationalam plifier circuit. [3]
(c) D raw th e circuit diagram of a differentialam plifier and derive an expression for th e output voltage in term s of th e input voltages and resistances in th e circuit. [16]
R 3
R 4
1k Ω
R 1
R 2
Vcc = 20V
SECTIO N B
- (a) W rite dow n th e equations of th e circuit of Figure Q 5 using:
(i) Mesh analysis; [6] (ii) Nodalanalysis. [6]
(b ) Using a suitab le diagram , clearly sh ow allth e currents flow ing and voltages in th e circuit. [10]
(c) State th e pow er output of th e 10∠ 00 V source. [3]
Figure Q 5
-j 1 Ω + j 1 Ω
4 Ω 6 Ω^
10 ∠ 00 V
G
- (a) D e rive from first principles th e expressions for ch aracteristic im pedance, Z (^) o, and propagation constant, γ= α+ jβ, for th e four term inalnetw ork sh ow n in Figure Q 6. [13]
Figure Q 6
(b ) State th e ch aracteristic im pedance and propagation constant of th e netw ork w h ich h as a series im pedance of 1+ 2jΩ and sh unt im pedance of - j 5 Ω. [6]
(c) Tw o of th ese netw ork s are connected in series and term inated in th eir ch aracteristic im pedance.
State th e ch aracteristic im pedance and propagation constant attenuation of th e com b ined netw ork s. [6]
Z 2 2
Z 1
Z 1
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- A t tim e t=0, th e sw itch is closed in th e circuit of Figure Q 8. Th is connects th e ram p generator to th e capacitor, C, th rough th e resistor, R. A lloth er initial conditions are zero.
(a) State w h at you th ink th e voltage across th e capacitor w illb e lik e. Consider a ram p voltage th at is greater and less th an th e tim e constant of th e circuit. [5]
(b ) Using Laplace tech niques, determ ine th e current flow ing in th e circuit after th e sw itch is closed, and h ence th e voltage across th e capacitor. [15]
(c) Calculate th e voltage across th e capacitor 1m s after th e sw itch is closed, w h en k =10, R = 1k Ω and C = 1μF. [5]
Figure Q 8
END
Vk t G
t=
C
R
