Electronic Circuits and Devices Question Paper of 3rd Semester ECE16 Download Previous Years Question Paper 3

Electronic Devices & Circuits

(EC-201, DEC-2005)

Note: Section A is compulsory. Attempt any four questions from Section B and any two questions from  Section C.

Section-A

1.

(a) What is the main important difference between the characteristics of a simple switch and those  of an ideal diode?

(b) Compare JFET and MOSFET. Mention at least four points.

(c) What is reverse Recovery Time?

(d) A dc voltage supply provides 60V when output is unloaded. When connected to a load the  output drops to 56V. Calculate the values of voltage regulation.

(e) What is “Dark current” of a photodiode?

(f) What is negative resistance region?

(g) Which two methods makes the collector current constant. Explain them.

(h) What is fold back limiting?

(i) Calculate dc voltage across 1 Kr load for a RC filter (R=120r, C=10m F). The dc voltage across  the initial filter capacitor is 60V.

(j) Draw the piecewise linear equivalent circuit of diode and explain it briefly.

Section-B

2. Explain the working of CMOS Invertor. Also mention the applications and advantages over other  approaches.

3.

(a) Describe the differences between re and hybrid equivalent for a BJT transistor.

(b) For each model, list the conditions under which it should be applied.

4. A full wave bridge rectifier with 120V rms sinusoidal input has a load resistor of 1kΩ.

 (i) If silicon diodes are employed, what is dc voltage available at load?

 (ii) Determine required PIV rating of each diode.

 (iii) Find maximum current through each diode during condition.

 (iv) What is required power rating of each diode?

5. A silicon transistor with β = 100 is to be used in self biasing circuit shown in figure below, such        that  the Q-point corresponds to VCE = 12V and IC = 2m A. Find RE if VCC = 24V and RC = 5KΩ.

Fig.

6.

(a) What is Miller Theorem?

(b) Explain analysis of emitter follower by using this theorem.

Section-C

7.

(a) What is the significant difference between the construction of an enhancement-type MOSFET  and a depletion type MOSFET?

(b) Sketch the circuit of a CS amplifier. Derive the expression for the voltage gain at low  frequencies.

8.

 (a) For a zener diode network shown in below fig. Determine VL , VR, IZ and PZ.

 (b) What do you mean by hot carrier diode? Compare the characteristics of hot carrier and p-n junction diode?

Fig.

9.

 (a) Design a self-bias network using a JFET transistor with IDSS = 8m A and VP = -6V to have a Qpoint at IDQ = 4m A using a supply of 14V. Assume the RD = 3RS and use standard values.

 (b) Discuss the three configurations of FET biasing. Explain any one in detail.