UPSC Deputy Central Intelligence Officer (Technical) and Joint Assistant Director Previous Year Paper 2019 conducted on 8th March 2020
Which one of the following has negative temperature coefficient ?
(a) Sensistor
(b) Thermistor
(c) Metal
(d) Heavily doped Semiconductor
What is the cutoff frequency of the op-amp, if unity gain frequency is 10 MHz and voltage differential gain is 50,000 ?
(a) 200 Hz
(b) 100 Hz
(c) 1000 Hz
(d) 2000 Hz
Which of the following elements are most frequently used for formation of p-type material by doping a pure germanium or silicon crystal with impurity atoms having three valence electrons ?
(a) Antimony, Arsenic, Boron
(b) Boron, Gallium, Arsenic
(c) Phosphorus, Boron, Gallium
(d) Boron, Gallium, Indium
Consider the following statements for sampling :
1. Flat-top sampling is preferred because of its noise immunity.
2. In natural sampling, the top of each rectangular pulse remains constant and is equal to the instantaneous value of the signal x(t) at the start of sampling.
3. One important reason for intentionally lengthening the duration of each pulse in flat-top sampling is to reduce the bandwidth.
(a) 1 and 2 only
(b) 1 and 3 only
(c) 2 and 3 only
(d) 1, 2 and 3
Consider the following statements regarding the logic circuits :
1. In combinational logic circuits, the outputs at any instant of time are entirely dependent upon the inputs present at that time.
2. The behavior of synchronous sequential circuit depends upon the order in which its input signals change and can be affected at any instant of time.
3. Synchronous sequential circuits that use clock pulses in the inputs of memory elements are called clocked sequential circuits.
Which of the above statements are correct ?
(a) 1,2 and 3
(b) 1 and 2 only
(c) 2 and 3 only
(d) 1 and 3 only
A ROM unit is organized as 512 words of 4 bits each. The number of input lines, output lines and the total storage capacity (in bits) of the unit respectively are
(a) 4, 9, 2048
(b) 9, 4, 4096
(c) 4, 9, 4096
(d) 9, 4, 2048
Which one of the following is intended to compensate for the loss of signal power incurred in the course of transmission ?
(a) Filtering
(b) Tuning
(c) Amplification
(d) Broadcasting
Which of the following major components are required for phase-locked loop ?
(a) Transmitter, receiver and channel
(b) Multiplier, adder and oscillator
(c) Multiplier, a loop filter and a voltage controlled oscillator
(d) Product modulator, adder and feedback resistor
The power spectral density of a wide-sense stationary random process is always
(a) Negative
(b) Zero
(c) Unity
(d) Non-negative
The video signal exhibits a large bandwidth and significant low-frequency content, which suggest the use of
(a) DSB-SC modulation
(b) SSB-SC modulation
(c) VSB modulation
(d) Frequency modulation
What is the frequency range of FM radio receivers ?
(a) 0.525 MHz- 1.605 MHz
(b) 88 MHz – 108 MHz
(c) 0.455 MHz – 10.8 MHz
(d) 8.8 MHz – 10.8 MHz
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