NMOS is constructed with the n-type source and drain and a p-type substrate, while PMOS is constructed with the p-type source and drain and an n-type substrate. In an NMOS, carriers are electrons, while in a PMOS carrier are holes. Where CMOS is the combination of NMOS and PMOS. CMOS technology uses less energy to operate at the same output and produces less noise during operation.
Lets check in details.
What is NMOS?
NMOS (nMOSFET) is a kind of MOSFET. An NMOS transistor consists of n-type source and drain and a p-type substrate. When a voltage is applied to the gate, holes in the body (p-type substrate) are driven away from the gate. This allows the formation of an n-type channel between the source and the drain, and a current is conducted from electrons from the source to the drain through an induced n-type channel.
Logic gates and other digital devices implemented using NMOSs are said to have NMOS logic. There are three operating modes in a NMOS called cut-off, triode and saturation. NMOS logic is easy to design and manufacture. Circuits with NMOS logic gates, however, consume static power when the circuit is idle, since DC current flows through the logic gate when the output is low.
What is PMOS?
PMOS (pMOSFET) is a MOSFET type. A PMOS transistor consists of a p-type source and drain and an n-type substrate. When a positive voltage is applied between source and gate (negative voltage between gate and source), a p-type channel with opposite polarities is formed between source and drain. A current is passed through holes from the source to the drain through a p-type induced channel.
A high voltage at the gate causes a PMOS to not conduct, while a low voltage at the gate causes it to conduct. Logic gates and other digital devices implemented using PMOS should have PMOS logic. The PMOS technology is inexpensive and has good immunity to interference.
What is CMOS?
Complementary Metal-Oxide-Semiconductor (CMOS) is an integrated circuit technology. CMOS technology is used in microprocessors, microcontrollers, static RAM and other digital logic circuits.
The CMOS technology is also used for various analog circuits such as image sensors (CMOS sensor), data converters and highly integrated transceivers for many types of communication.
The difference between NMOS, PMOS and CMOS transistors
NMOS:
- NMOS consists of n-type source and drain and a p-type substrate.
- In an NMOS, carriers are electrons When a high voltage is applied to the gate, the NMOS conducts If there is a low voltage at the gate, the NMOS will not conduct NMOS are said to be faster than PMOS because the charge carriers in NMOS, which are electrons, travel twice as fast as holes.
- NMOS ICs would be smaller than PMOS ICs NMOS can deliver half of the impedance delivered by a PMOS NMOS represents an N-type MOS transistor.
PMOS:
- PMOS is constructed with p-source and drain and an n-substrate.
- PMOS, carriers are holes. If a high voltage is applied to the gate, the PMOS will not conduct When a low voltage is applied to the gate,
- PMOS conducts Which are the carriers in PMOS.
- PMOS devices are less susceptible to interference than NMOS devices. PMOS represents a P-type MOS transistor.
CMOS:
- CMOS means complementary metal oxide semiconductor transistor.
- The CMOS circuit includes a PMOS transistor and an NMOS transistor.
- CMOS is more of a term from process technology.
Why do we use CMOS instead of PMOS and NMOS?
An advantage of CMOS over NMOS logic is that both low-high and high-low output transitions are fast since the on-state (PMOS) pull-up transistors are in contrast to the load resistors in NMOS logic have a low resistance. In addition, the output signal oscillates the full voltage between low and high rail.
