This set of Microelectronics Multiple Choice Questions & Answers (MCQs) focuses on “Microelectronics Basics – Set 2”.
1. From the following Energy Band diagram, choose the correct order of materials.
a) A-Insulator; B-Si; C-Ge
b) A-Semiconductor; B-Si; C-Ge
c) A-Semiconductor; B-Ge; C-Si
d) A-Insulator; B-Ge; C-Si
View Answer
Explanation: The bandgap energy represent in case of A makes it more of a semi-conductor rather than an insulator while we know that the bandgap energy of Si is more than Ge.
2. From the following Energy Band Diagram, choose the correct order of material.
a) Semiconductor, Metal, Metal
b) Metal, Metal, Semiconductor
c) Metal, Metal, Insulator
d) Metal, Semiconductor, Metal
View Answer
Explanation: The 2nd E.B.G. is showing a metal where the conduction and valence bands have overlapped while the 1st E.B.G. is showing a metal where the energy band gap is almost negligible. The 3rd E.B.G. shows a semiconductor with a finite energy band-gap.
3. What is the minimum number of variables required to represent a signal?
a) One
b) Two
c) Three
d) Four
View Answer
Explanation: A signal is always a function of at least two variables. Since a signal represents information, it has to be a function of at least two variables or we won’t be able to characterize this signal as some information.
4. Which of the following is a transducer?
a) Ear
b) Guitar
c) Ear and Guitar
d) Ear, guitar and wire
View Answer
Explanation: A transducer is said to convert one form of energy to another. The ear converts the vibrations or mechanical energy to sound energy while a guitar creates sound energy from mechanical energy. The wire simply allows the electrical energy to flow, it is not a transducer.
5. If n resistors are connected between two nodes and n-p resistors have resistance a while (n-q) resistors have resistance b- Choose the correct result derived among the following.
a) Each resistor of resistance a has a current – 1/q * (p/b)/(q/a + p/b) * Iin
b) Each resistor of resistance b has a voltage – 1/n * (p/b)/(q/a + p/b) * Vin
c) Each resistor of resistance a has a voltage – 1/n * (p/b)/(q/a + p/b) * Vin
d) Each resistor of resistance b has a current – 1/q * (p/b)/(q/a + p/b) * Iin
View Answer
Explanation: Firstly, we observe two sets of resistance – q number of a Ohms and p number of b Ohms. The input current will face a current divider and get divided into Ia and Ib which gets divided q times and p times while flowing through each resistor. Now, Ia is (p/b)/(q/a + p/b) * Iin which further gets divided q times and hence the correct result derived is 1/q * (p/b)/(q/a + p/b) * Iin.
6. What happens to the output of an amplifier if it is kept in saturation?
a) Amplified
b) Buffered
c) Clipped
d) Amplified but clipped
View Answer
Explanation: Keeping the amplifier in a linear region of operation is necessary if we want to keep the output varying with respect to the input. Otherwise the amplified output would get clipped at a certain level if the amplifier reaches saturation owing to high input.
7. Can we use an amplifier as a current source.
a) True
b) False
View Answer
Explanation: Amplifiers in saturation mode can be used as a source of current or voltage since they will supply a certain amount of it constantly.
8. What is the need for biasing?
a) Work in the q-point
b) Voltage Amplification
c) Increase and maintain the transconductance
d) Current amplification
View Answer
Explanation: Biasing an amplifier is helpful to keep it in the linear region and the q-point is a point in the Output current vs Input voltage where the transistor is said to be biased. The transconductance, a ratio of output current and input voltage, is an important parameter which allows us to characterize the efficient working of the amplifier and biasing maintains the transconductance which further keep the amplifier in the linear region.
9. What is the ratio of output resistance of a transconductance amplifier to that of a trans-resistance amplifier?
a) Very much greater to 1
b) More than 1
c) Less than 1
d) Very much greater than 1
View Answer
Explanation: The output resistance of a transconductance amplifier is much less than that of a transconductance amplifier. The former has to deliver a voltage to the load which shouldn’t suffer loss due to coupling with the output resistance. The latter has to deliver a current and no amount of current should flow into the output resistance of the amplifier.
10. Which of the following A.C. signal doesn’t change shape while passing through a circuit of electrical elements?
a) Sinusoidal
b) Triangular
c) Sigmoid
d) Square Pulse
View Answer
Explanation: The sinusoidal signal doesn’t suffer from a change of shape and is known to be the only signal to do so. This is because it contains only 1 frequency and would generate a response to the excitation of that particular frequency.
11. Based on frequency response, which of the following behavior is shown by a D.C. coupled amplifier?
a) Low-pass Amplifier
b) High-pass Amplifier
c) Band-stop Amplifier
d) Band-pass Amplifier
View Answer
Explanation: A D.C. coupled amplifier shows low pass characteristics while a Tuned amplifier shows band-pass characteristics.
12. The noise margin is a measure of _____ to signals.
a) Insensitivity
b) Sensitivity
c) Noise
d) Resistance
View Answer
Explanation: The output stays saturated to an extent until the Noise margin is crossed. This typical feature of integrated circuits is referred to as the insensitivity property and is helpful to make the output more immune to noise.
Sanfoundry Global Education & Learning Series – Microelectronics.
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