Difference between CMOS and NMOS Technology

Last Updated : 30 Apr, 2024

In this article, we are going to know about CMOS and NMOS technology. We will explore what is CMOS technology and it’s advantages. Then we will look at NMOS technology and its advantages. Then we will have insights into the differences between the CMOS and NMOS technology.

Table of Content

CMOS Technology
Operation of CMOS
NMOS Technology
Operation of NMOS
CMOS Vs NMOS Technology
Applications of CMOS and NMOS
Why CMOS Technology is Preferred?

What is CMOS Technology?

CMOS is an abbreviation that is used for Complementary Metal Oxide semiconductors. This technology is generally used for the construction of ICs. This CMOS technology is formed when PMOS and NMOS technology are combined together. It is often utilized in digital logic circuits, microcontrollers, microprocessors and static RAM. This CMOS technology is also identified as one of the leading semiconductor technologies. Its main features include low power consumption and high immunity against noise. Basically, CMOS is an onboard semiconductor chip that is utilized for the storage of data. It is powered by the battery.

CMOS Battery Lifetime

The Battery Lifetime of Complementary Metal Oxide Semiconductor Battery is dependent on various factors. The lifetime of the battery of CMOS is typically from 3 to 10 years. The battery lifetime is affected by various factors:

Storage Time: When the battery is not used for a very long time, then the lifespan of the battery may be reduced a little bit.
Temperature : The battery lifetime is also dependent on the temperature. When the temperature rises, the chemical reactions occurring within the battery is accelerated and so the battery lifetime decreases.
Quality : The battery lifetime of CMOS is also dependent on the manufacturer. The manufacturer of higher quality will make higher quality batteries, so that it lasts longer.
Environmental Factors : The battery lifetime of CMOS is also dependent on various environmental factors. Factors like humidity have effect on the battery lifetime.

CMOS Inverter

The lifetime of CMOS Inverter is different from that of CMOS battery. It doesn’t have any limitation on the lifetime. However it’s lifetime is dependent on the various factors:-

Electromigration : The CMOS inverter has some metal traces present in it’s structure. The metal traces present in the inverter may experience some electromigration. This led to the movement of metal atoms and this can led to failure of CMOS inverter.
Low Power Consumption : The CMOS inverters are designed in such a way that it utilizes less power. So, due to the usage of less power, it generates less heat and thus it increases it’s lifespan.
Physical Damage : The lifetime of the CMOS inverter is also dependent on various factors. It can get damaged due to physical obstruction.

CMOS

Operation of CMOS

In CMOS technology, it’s operation is done with the help of N-type and P-type transistors. We use both these transistors to construct the logic functions. In this technology, when one type of transistor is turned on by a signal. Then the same signal which turned on one signal will turn off the other transistor. We don’t need to use any extra resistors or equipment to control them. In CMOS technology, one network of transistors helps to bring down the output to the ground. While the other network of transistors helps to keep the voltage to a higher amount of voltage. So, in this way when one network is on then the other network is in off state.

What is NMOS Technology?

NMOS is an abbreviation which is used for N-Channel Metal Oxide Semiconductor. This NMOS technology is formed when two N-type semiconductor material and a P-type semiconductor material are combined together. It is that type of semiconductor which charges negatively. It is generally used for the designing of a variety of microelectronic circuits. Then these circuits are utilized in logic chips and memory chips. This technology operates faster than others because they contain electrons as the charge carriers having higher mobility.

NMOS Inverter

NMOS Inverters are the basic building blocks in digital electronic circuits. NMOS Inverters also consists of NMOS transistors. The NMOS transistors are an integral part of NMOS inverters. It is made up of N-type semiconductor material. It provides operation like shifting of input voltage level, inversion of input, etc. It is also used for the construction of of various digital logic gates. Logic gates like NAND, NOR, XOR gates are constructed by usage of NMOS inverter. It is less efficient when it comes to power consumption. It takes use of more power as compared to CMOS inverters.

NMOS

Operation of NMOS

The working of NMOS technology is like a switch. It can be turned on or turned off by utilizing a voltage control at its gate. In NMOS technology, whenever it receives voltage which becomes non-negligible then it forms a closed circuit. In this scenario, the connection between the drain and the source terminal only works as a wire. So, in this situation the flow of current is from the gate terminal to the source. When the received voltage is approximately 0V, then it leads to the formation of an open circuit. In open circuit, the connection between the drain and the source terminal is broken. Since the connection is broken between the drain and the source terminal, the flow of current is from gate terminal to the drain.

Differences between CMOS Technology and NMOS Technology

Aspect	CMOS	NMOS
Technology	CMOS is an abbreviation which is used for Complementary Metal Oxide Semiconductor.	NMOS is an abbreviation which is used for N-Channel Metal Oxide Semiconductor.
Logic Levels	The logic level of CMOS technology is 0 V / 5 V.	The logic level of NMOS technology depends on the Beta ratio.
Layout	CMOS offers more regular layout.	While NMOS offers irregular layout.
Packing Density	In CMOS, we have less packing density.	While in NMOS, we have high packing density.
Load/Drive Ratio	The load/drive ratio in CMOS is 1:1 or 2:1.	While the load/drive ration in NMOS is 4:1.
Mode of Operation	It make use of both depletion and enhancement mode transistors.	It make use of enhancement mode transistors only.
Characteristics	The noise immunity offered by CMOS technology is higher.	While the noise immunity offered by NMOS technology is lower.
Transmission Time	The transmission time offered by CMOS is higher than the NMOS.	The transmission time offered by NMOS is slower than CMOS.
Power Supply	It requires less power supply voltages to function.	It requires more power supply voltages to function.
Transmission Gate Behavior	It provides more efficient and reliable transmission gate behavior.	It provides less efficient and unreliable transmission gate behavior.
Pre-charging Scheme	It makes use of dynamic pre-charging schemes.	It does not make use of dynamic pre-charging schemes.
Power Dissipation	The power dissipation offered by CMOS is lower.	While the power dissipation offered by NMOS is higher.
Primary Use	It is utilized in the digital integrated circuits.	It is used in digital circuits, but nowadays they are used less.

Advantages and Disadvantages of CMOS

Here are some Advantages and Disadvantages of CMOS given below :

Advantages of CMOS

It offers high immunity against noise.
It have low power consumption.
The overall complexity of the circuit gets reduced when we use CMOS technology.
It provides high density of logic functions on a single chip.
The heat produced by the usage of CMOS technology is very less.

Disadvantages of CMOS

The packaging density of CMOS technology is lower when compared to NMOS technology.
When the processing steps increases in CMOS technology, then it’s cost also increases.
It make use of more number of transistors.
It consumes more amount of space over the chip.
It needs to be protected from getting the static charges.

Advantages and Disadvantages of NMOS

Here are some Advantages and Disadvantages of CMOS given below :

Advantages of NMOS

It offers faster switching speeds.
It operates faster than other technology.
These semiconductors requires less fabrication.
It offers high packing density.
It is used for construction of logic gates and digital circuits.

Disadvantages of NMOS

It consumes more power as compared to CMOS.
It have limited voltage levels for representing the logic states.
The switching speed offered by NMOS is slower as compared to the CMOS.
The usage of NMOS technology is now getting reduced day by day.
It has lower voltage noise margins.

Applications of CMOS and NMOS

Here are some Advantages and Disadvantages of CMOS given below :

Applications of CMOS

CMOS are used for the fabrication purpose of digital integrated circuits.
They are often utilized in Radio Frequency circuits and it’s applications.
They are further used in power management circuits which includes voltage regulators.\
It is used for the stabilization of temperature.
It is taken into use for designing of application-specific integrated circuits (ASICs)

Applications of NMOS

It is used in Educational and Research Purposes.
It is utilized in sensor interface circuits.
They are still used in legacy and older systems and also utilized as a replacement part.
It is used in analog integrated circuits to increase the speed of process.
The fabrication of microprocessors, memory chips, logic circuits, etc are done using this technology.

Why CMOS Technology is Preferred Over NMOS Technology?

CMOS Technology is Preferred Over NMOS Technology because of the following reasons:-
CMOS technology consumes less power as compared to the NMOS technology.
CMOS technology offers higher packing density when compared to the NMOS technology.
CMOS circuits are less susceptible to noise when compared to the NMOS technology.
The switching speed offered by CMOS is faster than NMOS.
The components of CMOS technology is available in extensive quantity, so it is easy to use the CMOS technology.

Conclusion

In conclusion, CMOS and NMOS are the two most known types of Metal Oxide Semiconductor(MOS). Both CMOS and NMOS have their own characteristics. Both have their use cases in various fields. CMOS offers lower power consumption while NMOS offers higher mobility speed.