Digital Circuits Questions and Answers – Characteristics of CMOS

Digital Circuits Questions and Answers – Characteristics of CMOS

This set of Digital Electronics/Circuits Multiple Choice Questions & Answers (MCQs) focuses on “Characteristics of CMOS”.

1. The full form of CMOS is ____________
a) Capacitive metal oxide semiconductor
b) Capacitive metallic oxide semiconductor
c) Complementary metal oxide semiconductor
d) Complemented metal oxide semiconductor

Answer: c
Explanation: The full form of CMOS is complementary metal oxide semiconductor. In this type of device, both n-type and p-type transistors are used in a complementary way.

2. The full form of COS-MOS is ____________
a) Complementary symmetry metal oxide semiconductor
b) Complementary systematic metal oxide semiconductor
c) Capacitive symmetry metal oxide semiconductor
d) Complemented systematic metal oxide semiconductor

Answer: a
Explanation: The full form of COS-MOS is complementary systematic metal oxide semiconductor. In this type of device, both n-type and p-type transistors are used in a complementary way. Usually, the transistors used are MOSFETs.

3. CMOS is also sometimes referred to as ____________
a) Capacitive metal oxide semiconductor
b) Capacitive symmetry metal oxide semiconductor
c) Complementary symmetry metal oxide semiconductor
d) Complemented symmetry metal oxide semiconductor

Answer: c
Explanation: CMOS is also sometimes referred to as complementary systematic metal oxide–semiconductor (COS-MOS). In this type of device, both n-type and p-type transistors are used in a complementary way. Usually, the transistors used are MOSFETs.

4. CMOS technology is used in ____________
a) Inverter
b) Microprocessor
c) Digital logic
d) Both microprocessor and digital logic

Answer: d
Explanation: CMOS technology is used in Microprocessor, Microcontroller, static RAM and other digital logic circuits. CMOS technology is also used for several analog circuits such as image sensors (CMOS sensor), data converters and highly integrated transceivers for many types of communication.

5. Two important characteristics of CMOS devices are ____________
a) High noise immunity
b) Low static power consumption
c) High resistivity
d) Both high noise immunity and low static power consumption

Answer: d
Explanation: Two important characteristics of CMOS devices are high noise immunity and low static power consumption. Since one transistor of the pair is always off and the series combination draws significant power only momentarily during switching between on and off states. Also, the performance of CMOS is not altered with the presence of noise and thus it has high noise immunity.

6. CMOS behaves as a/an ____________
a) Adder
b) Subtractor
c) Inverter
d) Comparator

Answer: c
Explanation: Since, the outputs of the PMOS and NMOS transistors are complementary such that when the input is low, the output is high and when the input is high, the output is low. Because of this behaviour of input and output, the CMOS circuit’s output is the inverse of the input. Whereas, adders and subtractors are combinational circuits.

7. An important characteristic of a CMOS circuit is the ____________
a) Noise immunity
b) Duality
c) Symmetricity
d) Noise Margin

Answer: b
Explanation: An important characteristic of a CMOS circuit is the duality that exists between its PMOS transistors and NMOS transistors. Due to the presence of two different types of transistors, the device has the complementary function.

8. CMOS logic dissipates _______ power than NMOS logic circuits.
a) More
b) Less
c) Equal
d) Very High

Answer: b
Explanation: CMOS logic dissipates less power than NMOS logic circuits because CMOS dissipates power only when switching (“dynamic power”). Thus, CMOS has less power consumption and is more efficient.

9. Semiconductors are made of ____________
a) Ge and Si
b) Si and Pb
c) Ge and Pb
d) Pb and Au

Answer: a
Explanation: Semiconductors are made of Silicon (Si) and Germanium (Ge). Semiconductors are devices having conductivity between conductors and insulators.

10. Which chip were the first RTC and CMOS RAM chip to be used in early IBM computers, capable of storing a total of 64 bytes?
a) The Samsung 146818
b) The Samsung 146819
c) The Motorola 146818
d) The Motorola 146819

Answer: c
Explanation: The Motorola 146818 was the first RTC and CMOS RAM chip to be used in early IBM computers; capable of storing a total of 64 bytes.

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