Andhra University BE/B.Tech Electronics Previous Paper 2004
Question No.1 is compulsory.
Answer any FOUR questions from the remaining.
All Questions carry equal marks.
Answer all parts of any questions at one place.
1(a)Define diffusion current density and Hall effect.
(b)A force of F=3αx PN and an electric field of 5αx µ v/m exist in a charged region. Find the charge in the region.
(c)Define forward and reverse recovery times in PN diodes.
(d)Draw the V-I characteristics of UJT.
(e)Draw the simplest possible transistor amplifier circuit.
(f)Define operating point in a transistor and stability factors.
(g)Define ripple factor and percentage regulation.
2(a)List out the characteristics of Silicon and Germanium.
(b)What are the applications of Hall effect and describe a method of determination of N or P-type of materials.
3(a)Describe Transition and diffusion capacitances in PN diodes.
(b)The current in the reverse biased PN diode made of Ge is 0.2 µA. When the applied voltage is 0.1v.Find the current at room temperature. Also find out the current in silicon diode.
4(a)Obtain the relation between α and β of transistors.
(b)If the emitter current ,IE=1.2 mA and β=60,find α, IB and IC.
5(a)Derive and expression for the stability factor S of self-bias transistor circuit.
(b)For the circuit of fig1,find RB required to obtain the optimum operating point when VBE=0.6V,β=100,VCE=5V
6(a) Compare the characteristics of JFET and BJT in detail.
(b)If two JFETS are connected in parallel with rd1=20KΩ,rd2=30KΩ and gm1=2 mmho,gm2= 4mmho,find effective gm and rd.
7(a)Draw the circuit of full-wave rectifier with capacitor filter and its output waveform. Obtain an expression for its ripple factor.
(b)Design a π-section filter full wave circuit to obtain a ripple factor of 0.01 at a frequency of 50Hz.
8 Write short notes on:
(c)Tunnel diodeshttp://www.stepinau.com/2013/09/26/andhra-university-beb-tech-electronics-previous-paper-2004/IT 2.1 Previous PapersCSE,CSE Previous Papers,Electronics Previous Papers,IT,IT Previous Papers