Department of EEE Analog System Design [ELE 210]

First Assignment Date of Assignment : 23-02-2012 Last Date for Submission :08-02-2012

1. For the circuit shown in fig. (1) , (a) evaluate the overall gain A, (b) specify suitable

components to make overall gain A variable over the range -100 V/V ≤ A ≤ 0 by means of

100 kΩ pot. Try minimising the numbers of resistors you use.

Fig. (1)

2. Using two Op-amps, design a circuit such that output VO = 4VA -3VB + 2VC –VD. Select

feedback resistance Rf = 30 kΩ.

3. Design a two input, two output circuit that yields the sum and the difference of inputs: VS =

V1 + V2, and VD = V1 – V2.

4. For a basic differentiator circuit with C = 10nF and R = 100 kΩ, let VI be a periodic signal

alternating between 0 V and 2 V with a frequency of 100 Hz. Sketch VI and VO versus time if

VI is (a) a sine wave ; (b) a triangular wave.

5. Using just one op amp powered from ± 15 V supply voltages, design a circuit that accepts

an ac input VI and yields VO = VI + 5V, under the constraint that the resistance seen by the

ac source be 100 kΩ.

6. From pole-zero concept obtain the 6th order Butterworth polynomial. Hence design 6th

order High Pass Butterworth filter with half power frequency equal to 10 kHz. Assume C =

0.1 µF and feedback resistance Rf = 10 kΩ.

7. Design a narrowband bandpass filter with a resonant frequency 100Hz and Q =10 and mid-

band gain 50 V/V. Assume C = 0.1 µF.

8. Design a wideband band pass filter with half power frequencies 1 KHz and 10 KHz and stop

band roll off equal to 40 dB/decade. Assume C = 0.1 µF and Rf = 10 kΩ.

9. Realize a circuit to implement a VTC as shown in fig 9(a) and 9(b).Vsat=12V and a sine wave

is applied to the input terminal .Draw the output voltage along with the input waveform.

OA1

OA2

+-

R3

VoVi

R1

R2

R4

10. Derive an expression for the input resistance Ri in the circuit shown in fig Q10. Assume

open loop gain of op-amp is A(very large)

11. Show that the floating load V-I converter in the circuit shown in fig Q11 yields i0=KR

vi

/1

where K=1+R2/R3.

12. Using comparators, Zener diodes(IR≈1mA Vz=5V), resistors, LED’s( ILED≈1mA, VLED≈1.8V) design a circuit that monitors a 12V car battery and causes the first LED to glow whenever the battery voltage rises above 13V, and causes the second LED to glow whenever it drops below 10V. Use Vcc = ±12V as bias voltage.

13. From the fundamentals, derive an expression for the non inverting Schmitt trigger with

VLTP<0 and VUTP>0 and = .

14. With a neat circuit diagram explain the following

I. Peak detector

II. Sample and Hold

III. Full wave precision rectifier

10V

-7V

2V 5V

Fig(9 b)

vin

vout

+9v

-4v

vin

vout

5v-2.5v

fig 9a

R1

R2

R3

Ri Fig Q10

R1

R2

R3

Fig Q11

Load

i0Vi

15. Derive an expression for the output V0of the Op-amp based circuit shown in figure Q1. Hence plot

the output with respect to time. Simulate using Spice to verify your result.

16. Design and develop a circuit to solve differential equations. Assume initial conditions are zero.

a)

.

b)

.

17. Discuss the difference between Active and Passive filters.

Note: Simulate the questions 2,4,6,7,8,9,12,15 using PSpice and verify your results.

+

-

1K 1K

1K

1K2sin(314t)

1V

V0

Fig Q15.