Analogue Electronics and Instrumentation - 1999 2000 Exam - Electrical Engineering, Exams of Electrical Engineering

Download Analogue Electronics and Instrumentation - 1999 2000 Exam - Electrical Engineering and more Exams Electrical Engineering in PDF only on Docsity! S451 02/09/02 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 19 9 9 /2000 Exam ination for th e BEng (H O NS) ELECTR ICA L AND ELECTR O NIC ENGINEER ING (FULL-TIME/PA R T-TIME/SA N D W ICH ) BEng (H O NS) ELECTR O NIC ENGINEER ING (PA R T-TIME) YEA R TW O UNIT 64EE2072: ANALO GUE ELECTR O NICS AND INSTRUMENTATIO N W ednesday 17 May 2000 9 .30am to 11.30am Instructions to Candidates A nsw er any FO UR questions. A ll questions carry equal m ark s. 1 continued Break dow n of m ark s for each question is sh ow n in square parenth eses. 4 continued 3 (a) D e scrib e b riefly th e effect on a real operational am plifier circuit of th e im perfection Input O ffset Voltage. D e scrib e th e source of th is property and state an equation th at defines th e term . State a typical value for a 741 op-am p and th e factors on w h ich its m agnitude depends. [6] (b) D e scrib e h ow th e circuit in Figure Q 3 can be used to analyse th e effect of input offset voltage on th e am plifier perform ance. [3] Figure Q 3 (c) A nalyse th is circuit to derive an expression for th e output voltage due to an input offset voltage Vos. H ence state an equation for th e total am plifier output voltage due to both input voltages. [10] (d) H ence calculate th e value of Vos for an am plifier of th e form in Figure Q 3 w h ere V0 = -0.2 V, Vin = + 3 m V, R 1 = 1 k Ω and R 2 = 100 k Ω. [6] 4 (a) State th e m ain reason for th e finite bandw idth of an integrated circuit operational am plifier. W rite an equation for its open loop voltage gain and define th e various term s involved. Sk etch curves to sh ow th e variations of gain and ph ase sh ift w ith frequency. W rite th e com m only used approxim ation for th e gain equation th at is used in m ost circum stances.[10] Figure Q 4 (b) W rite four equations th at describ e th e b e h aviour of various aspects of th e op-am p and th e circuit in Figure Q 4 for sinusoidal input signals of frequency f H z. H ence derive an expression for th e am plifier voltage gain. From th is equation state expressions for th e passband am plifier gain and th e 3 dB bandw idth . [15] + _ R2 R1 V0 G Vos + G Vin = 0 ideal op amp + _ R2 R1 G vin v0 5 S451 02/09/02 5 (a) D raw a circuit diagram of th e tw o-stage instrum entation am plifier and explain b riefly th e functions of each stage. State th e m ain advantages of th is form of am plifier com pared w ith th ose containing only one op-am p. [9 ] (b) A nalyse each of th ese stages and h ence derive an expression for th e transfer function of th e w h ole am plifier. [16] 6 (a) W ith th e aid of a suitable graph and an equation, describ e b riefly th e ch aracteristic of a resistance tem perature detector (R TD ) th at enables it to be used to m easure tem perature. D e scrib e b riefly th e principle norm ally used for tem perature m easurem ent. State also th e possible problem arising from th e level of current passing th rough th e device and state th e equations th at determ ine th is b e h aviour. [10] (b) D raw th e diagram of a signal conditioning circuit for an R TD and, w ith th e aid of suitable graph s, describ e th e b e h aviour of th e circuit. [15] 7 (a) D raw a diagram of th e dual ram p digital voltm eter and, w ith th e aid of a suitable tim ing diagram , explain th e various stages in th e m easurem ent process. [10] (b) A nalyse th e circuit to derive an expression for th e output reading from th is instrum ent. [10] (c) H ence deduce w h y th is instrum ent can claim h igh m easurem ent accuracy. Explain som e aspects of circuit design w h ich lim it its accuracy. [5] END