# VTU Old Exam Papers BE EC 4th Semester

# Linear IC’s and Applications July 2006

**Note : 1. Answer any Five full questions.**

**2. Missing data, if any may be assumed suitably**

1 a) Show that for a differential amplifier the output voltage depends on the differential mode gain (Ad) as CMRR tends to infinity.

b) Explain the different stages of an OPAMP with a neat circuit diagram.

c) Discuss the conditions and concept of virtual ground.

2 a) Define the following terms and indicate their typical values for MA741C OPAMP i) Slew rate, ii) Gain bandwidth product, iii) Input bias current.

b) The following circuit (fig 2.b) has identical transistors with same beta (/?). Show that

( c) What is the need of compensation? Explain the different methods of compensation in brief.

3.(a) For.a Nonr-Inverting OPAMP with Ri^{=£}», Ro~0, show that A_{V}f=*—where A_{V}f:

(1 + A_{v})R + R_{f} Gain with feed back., Ay: Open loop voltage gain.

b) Design an OPAMP circuit to obtain the following output with Ay= co and R_{x}= go K = -^(8r,-4K+v_{3}) 16

c) An OPAMP has Rj= oo ■ R_{0}~0 and Ay=l 0^{6}. If Rp=47k and R=1 OK, Determine Avf, Z_{if}

4 (a) Design a practical integrator to integrate the frequency range above IKHz. Assume Cf=0.1MF

b) Draw the circuit diagram of a negative peak detected and explain the function.

c) Design a second order Butter worth Low pass filter with cut off frequency of 200Hz and plot the frequency response of the filter.

5 a) Derive the expression for free running frequency of the 555 Astable Multivibration. Explain with neat circuit diagram. –

b) Determine the component values necessary for the 555 timer astable multivibrator having the free running frequency of 900.Hz with 65% duty cycle. Assume timing- capacitor C=0.22 fjF

6 a) Define the following terms : i) Resolution, ii) Linearity, iii) Monotonicity

b) Calculate the values of LSB, MSB, and full scale output and resolution of an 8 bit DA C in the range 0 to 10V.. ‘

c) With a neat circuit diagram and wave forms explain the principle of operation of Dual Slope ADC. Also show that the result is independent of RC time constant.

7 a) Explain the principle of operation of a phase locked loop with a neat block diagram.

b) Explain the application of PLL(IC565) for FSK detection with a neat circuit diagram.

c) Draw the functional block diagram of IC 723 regulator and explain how it can be used as a high voltage regulator.

8 Write short notes on any three of the following :

a) Switching regulator

b) Successive approximation ADC

c) Log and anti log amplifiers

d) Schmitt trigger and its applications*