Analog Electronics 2 - May 2015
Electronics & Telecomm. (Semester 4)
TOTAL MARKS: 80
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any three from the remaining questions.
(3) Assume data if required.
(4) Figures to the right indicate full marks.
Solve any four:
1 (a) Define the CMRR of Differential Amplifier? Why constant current source biasing is preferred for Differential Amplifier.(5 marks) 1 (b) What is the major limitations of class B power amplifier and how to overcome the same?(5 marks) 1 (c) Draw high frequency hybrid pi equivalent circuit of a BJT and define various components in the model.(5 marks) 1 (d) Draw the circuit diagram of widlar current current source and derive the relationship between output current and reference current.(5 marks) 1 (e) A zener voltage regulator as shown below has Vz=6.2 V. The input voltage varies from 10V to 15V and load current is 50 mA. To hold output voltage constant under all conditions what should be the range of series resistance (Rsmin and Rsmax) (Izmin=10mA, Pzmax=2W) (5 marks) 1 (f) Draw subtractor using OPAMP and also derive expression for its output voltage.(5 marks) 2 (a) For the circuit shown in Fig 2a. The transistor parameters are VBE(ON) =0.7V, β=100, CΠ=2 pF, Cμ=0.2 pF. (10 marks) 2 (b) Draw the circuit diagram MOSFET based differential amplifier and derive the expression for differential gain, common mode gain and CMRR.(10 marks) 3 (a) For the circuit shown in below. Transistors parameters are Kn=1m A/V2, Vtn=0.7V, Cgs=2 pF, Cgd=0.2 pF λ=0. Find the miller capacitance, mid band voltage gain and upper cut off frequency. (10 marks) 3 (b) What are the ideal characteristics of OPAMP and also explain effect of high frequency on OPAMP gain and phase.(5 marks) 3 (c) Draw the circuit of VBE multiplier biased class AB amplifier and explain the working and advantages of VBE multiplier biased class AB amplifier.(5 marks) 4 (a) Determine overall input resistance and output resistance of the circuit as shown in below. For the both transistors β=120. (10 marks) 4 (b) For the circuit shown in below. Transistors parameters are β=100, VBE(ON)=0.7V, VA=∞. The constant source has a finite output resistance of 100K. Find : i) Differential and common mode input resistance. ii) Find Ad, Ac and CMRR of the circuit. (10 marks) 5 (a) Draw the circuit of OPAMP based differentiator circuit and derive the expression for output voltage. What are the limitations of ideal differentiator circuit and how to overcome the limitations?(10 marks) 5 (b) In the MOSFET cascode current source shown in below, all transistors are identical with parameters. VTH=1V, Kn=80 μ A/V2 and λ=0 Let IREF=20 μA. The circuit is biased at V+=5V and V=-5V determine i) VGS of each transistors ii) The lowest possible voltage value of VD4. iii) Output resistance Ro. (10 marks)
Write short note on any three:
6 (a) Series Voltage regulator(7 marks) 6 (b) Class AB power amplifier(7 marks) 6 (c) Active filters(7 marks) 6 (d) Power MOSFET(7 marks)