# Placement Papers - DRDO DRDO Placement Paper Model For ECE ( Technical)
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Rajivkumar
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Paper: DRDO Placement Paper Model For ECE ( Technical)

Direct Theory question:

1. A triangular-square wave generator uses
* A sine wave oscillator and a comparator
* An integrator and a comparator
* A differentiator and comparator
* A sine wave oscillator and a clipper

2. An amplifier has two identical cascaded stages. Each stage has a BW of 20KHz. The overall BW shall be
* 10KHz
* 12.9KHz
* 20KHz
* 28.3HHz

Direct numerical problem:

1. A parabolic dish antenna has a diameter of 1m. the maximum possible ideal gain of the antenna at a wavelength 3.14cm is
* 20 dB
* 30 dB
* 40 dB
* 50 dB

2. The frequency deviation produced in a VHF carrier by a signal of 100Hz is 50KHz. The frequency modulation is

Application based theoretical or numerical problem:

1. Which one of the pulses has the same form in time domain as well as in frequency domain
*Rectangular
*Exponential
*Triangular
*Gaussian

2. Good voice reproduction via PCM requires 128 quantization levels. If the BW of voice channel is 4KHz then data rate is
*256 Kbps
*128 Kbps
*56 Kbps
*28 Kbps

3. Match the following:
1. List 1 List2
A. Thyristor 1. Second break down
B. MOSFET 2. Large on-state drop
C. IGBT 3. Small on state drop
D. BJT 4. Slow device

Codes:
(a) A-4, B-3, C-2, D-1 (b) A-1, B-2, C-3, D-4
(c) A-4, B-2, C-3, D-1 (d) A-1, B-3, C-2, D-4

4. List 1 List2

A. Free and forced response 1. Discrete time systems
B. Z transform 2. Dirichlet conditions
C. Probability theory 3. Non-homogenous differential equation
d. Fourier series 4. Random process
Codes:

(a) A-1, B-3, C-2, D-4 (b) A-3, B-1, C-2, D-4
(c) A-1, B-3, C-4, D-2 (d) A-3, B-1, C-4, D-2

Assertion and reasoning type:

The following item consists of two statements labeled as Assertion A and the other as Reason R. Use the following codes:
(a) Both A&R are individually true and R is the correct explanation of A
(b) Both A & R are individually true and R is not the correct explanation of A
(c) A is true and R is false
(d) A is false and R is true

5. Every materials has a different value of energy band gap except metals which have no band gap
R The energy band gap is decided by the equilibrium lattice constant, which is different in different materials.

6. AOp-amp are commonly used in instrumentation Op-amps do not load the circuit due to their very high input impedance