ELECTRONIC CIRCUITS — I QUESTION BANKS PREVIOUS YEAR COLLECTIONS WITH SOLUTIONS ANSWER KEY

B.E./B.Tech. DEGREE EXAMINATION, APRIL/MAY 2010

Third Semester

Electronics and Communication Engineering

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EC2205 — ELECTRONIC CIRCUITS — I

(Regulation 2008)

Time: Three hours Maximum: 100 Marks

Answer ALL Questions

PART A — (10 × 2 = 20 Marks)

1. Define stability factor.2. Calculate the value of feedback resistor (Rs) required to self bias an N-channelJFET with IDSS = 40 mA, Vp = -10 v and VGSQ = -5V.3. Define Miller's theorem.4. What is the coupling schemes used in multistage amplifiers?5. Give the expressions for gain bandwidth product for voltage and current.6. What do you mean by amplifier rise time?7. What is cross over distortion?8. Draw the circuit of Class-D amplifier.9. Compare the half-wave and full-wave rectifiers.10. What are the advantages of SMPS?PART B — (5 × 16 = 80 Marks)11. (a) (i) Explain the fixed bias method and derive an expression for thestability factor. (8)(ii) Explain the voltage divider bias method and derive an expressionfor the stability factor. (8)Or(b) (i) Explain the circuit which uses a diode to compensate for changes inVBE and in ICO. (12)(ii) Discuss the operation of thermistor compensation. (4)12. (a) (i) Derive the expressions for the following of a small signal transistoramplifier in terms of the h-parameters(1) current gain(2) voltage gain(3) input impedance(4) output admittance. (12)(ii) Compare CB, CE and CC amplifiers. (4)Or(b) (i) Explain the operation of emitter coupled differential amplifier. (12)(ii) Discuss the transfer characteristics of the differential amplifier. (4)13. (a) Discuss the low frequency response and the high frequency response ofan amplifier. (16)Or(b) Explain the operation of high frequency common source FET amplifierwith neat diagram. Derive the expression for (i) voltage gain (ii) inputadmittance (iii) input capacitance (iv) output admittance. (16)14. (a) (i) Explain the operation of the transformer coupled class A audiopower amplifier. (12)(ii) Explain the terms conversion efficiency and maximum value ofefficiency used in audio power amplifiers. (4)Or(b) Explain the operation of the class-B push pull power amplifier with neatdiagram and list its advantages. (16)15. (a) Derive the expressions for the rectification efficiency, ripple factor,transformer utilization factor, form factor and peak factor of(i) half wave rectifier(ii) full wave rectifier. (16)Or(b) Explain the operation of(i) Voltage multiplier (8)(ii) Switched mode power supply. (8)