Code: A-20

AMIETE – ET/CS/IT (NEW SCHEME) - Code: AE54/AC54/AT54

Subject: LINEAR ICs & DIGITAL ELECTRONICS

Time: 3 Hours Max. Marks: 100

NOTE: There are 9 Questions in all.

· Question 1 is compulsory and carries 20 marks. Answer to Q. 1 must be written in the space provided for it in the answer book supplied and nowhere else.

· Out of the remaining EIGHT Questions answer any FIVE Questions. Each question carries 16 marks.

· Any required data not explicitly given, may be suitably assumed and stated.

Q.1 Choose the correct or the best alternative in the following: (210)

a. An op-amp has common mode gain of 50 dB and its CMRR is 150 dB. The differential gain of it will be__________

(A) 7500 dB (B) 200 dB

(C) 100 dB (D) 3 dB

b. The output voltage V_o in the given op-amp circuit as shown in Fig. 1 (b) is

(A) – 10 V (B) + 6 V

(C) + 8 V (D) + 10 V

c. Schmitt trigger is also called as____________

(A) Astable Multivibrator. (B) Monostable Multivibrator

(C) Bistable Multivibrator (D) Square wave Generator

d. The main advantage in using a three op-amp instrumentation amplifier over a single op-amp difference amplifier lies in

(A) Higher value of CMRR

(B) Lower noise Figure

(C) Elimination of the need for accurate matching of resistors

(D) Simplicity of gain adjustment

e. The output voltage of the op-amp as shown in Fig. 1(e), will be

(A) – 210 mV (B) 200 mV

(C) – 200 mV (D) + 210 mV

f. The number of bytes in a 32-bit string is

(A) 2 (B) 4

(C) 6 (D) 8

g. According to Demorgan’s Second theorem _________

(A) A NAND gate is always complementary to an AND gate

(B) An AND gate is equivalent to a bubbled NAND gate

(C) A NAND gate is equivalent to a bubbled AND gate

(D) A NAND gate is equivalent to a bubbled OR gate

h. An EX-OR gate produces high output only when two inputs are

(A) High (B) Low

(C) Different (D) Equal

i. A square wave with a period of 10 drives a T-flip flop. The period of the output signal will be

(A) 100 (B) 20

(C) 10 (D) 5

j. The factors to be considered in the design and application of Successive-approximation ADC’s are

(A) Stability and regulation of the reference voltage source

(B) Overload and recovery characteristics of the comparator

(C) Characteristics of analog switches speed and response of the ladder network

(D) All the above

Answer any FIVE Questions out of EIGHT Questions.

Each question carries 16 marks.

Q.2 a. List six characteristics of an ideal op-amp. (3)

b. Obtain closed loop gain of practical Non-Inverting operational amplifier. (7)

c. In Non-Inverting amplifier, the input voltage V_in = 0.6 V, feed back resistor

R_f = 10 k, R₁= 2.2 k, load resistor connected at output with respect to

ground is 1 k. Calculate (i) closed loop gain (ii) output voltage (iii) load current (iv) output current I_o flowing from the output terminal of the op-amp.

(6)

Q.3 a. Draw and explain the compensating circuit

(a) for input offset voltage

(b) Bias current in op-amp inverting amplifier (6)

b. With neat circuit diagram, explain the working of three op-amp Instrumentation amplifier. (6)

c. In inverting summing amplifier shown in Fig. 3 (c) below, solve for R₁and R₂ if output voltage V_o is average of two inputs V₁ and V_2. (4)

Fig. 3 (c)

Q.4 a. Draw sample and hold circuit. Explain its operation and indicate its uses. (6)

b. Design practical op-amp differentiator that will differentiate an input signal with f_max = 500 Hz. (5)

c. Design Schmitt Trigger circuit for the following specifications:

= +3 V, = + 1 V, V_sat = 10 V. (5)

Q.5 a. With neat circuit diagram and waveform, explain the working of op-amp as a Astable Multivibrator and show that T = 2 RC ln . (8)

b. With neat circuit diagram, explain the 3-bit DAC (R-2R Ladder DAC). (5)

c. Design the values of R and C in Monostable Multivibrator using 555 timer, so that output remains in high state for 0.5 m seconds. (3)

Q.6 a. Explain functional diagram of Digital Computer. (6)

b. What is parity bit? Explain Even parity and Odd parity method for Error detection. Why can’t the parity method detect a double error in transmitted data? (4)

c. Perform the following conversions:

(i) (5467)₁₀(?)₁₆(ii)(6327.45)₈(?)₁₀ (iii) (3FC.82)₁₆(?)₈ (6)