Analog Electronics (INDSC1A) — DU B.Sc. (Hons) Instrumentation Previous Year Question Papers

(c) What are piezoelectric crystals? Why are they used in oscillators? Explain. Name. of the Paper : AnalogElectronics 1. (a) Explain the effect of temperature on diode (3) (b) Discuss the role of couplingand bypass capacitor (3) (c) What is oscillator? Explain the criteria for (d) Derive the relation between a and B of BJT. (3) (e) If the emitter current of a transistor is 8 mA and Ip is 1/50 of lo, determine the levels of I, and Ip. (3) (f) What do you understand by cross-over distortion? How can it be eliminated in Class B-operation? 2. (a) Derive the expression for ripple factor and efficiency of a half-wave rectifier. (b) Discuss the effect of negative feedback on gain and bandwidth in the amplifier circuit. (c) Calculate the closed loop gain for the negative feedback amplifier when open loop gain A, = 200,000 and B = 1/200.Also calculate closed (6) loop gain when A, is increased by 70%. 7. (a) State the working of Colpitts oscillator using BJT 1, and derive the expression for its frequency of (8) sustained oscillations? (b) It is required to generate an output frequency of 140 KHz using Colpitts oscillator. Determine the (3) value of C, and C, given L = 0.7 mH. Assume 5. (a) Derive the expression of frequency of sustained oscillationsgeneratedbyRCphaseshiftoscillator with 3 RC networks. (b) What is the need for 3 RC circuits in a phase shift oscillator? Calculate the frequency of oscillation of a BJT phase shift oscillator using component values R = 100 kQ and (c)Draw and explain the Input and Output I(` characteristics of NPN common base transistor. 6. (a) Derive the expression of input impedance, output impedance and gain of a Voltage shunt feedback circuit. (b) Draw the output for the following circuits (6) (c) Differentiate between transition and diffusion 3. (a) (i) Determine Vy, I, Iz, and Ip for the network of figure given below, if R, = 470S. (it) Determine the value of R, that will establish maximum power conditions for the Zener diode. (iii) Determine the minimum value of R, to ensure that the Zener diode is in the "on" state. (b) Draw the block diagram of a power supply and (6) explain the functioning of each block. : (c) Draw the simplified h-equivalent circuit of common (4) emitter (CE) amplifier. 4. (a) For a voltage divider bias circuit with Vcc = 15V, R,=25kg, R,= 5kg, Rc= 3kQ, R= IkR and 1ge = 50. Determine the operating point current and (b) Explain with the help of a diagram the frequency response of a CE amplifier. Also explain why the gain falls at low and high frequencies. (c) What are power amplifiers? Classify the power amplifiers according to their operating cycle and