PMOS and NMOS

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Timeline

Timeline

2025-12-26

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This article introduces the basic concepts, physical structures, and operating characteristics of PMOS and NMOS, details the definitions of source, drain, and gate, and compares the differences between NMOS and PMOS in terms of voltage control methods, current flow directions, applicable switch types, and semiconductor substrate and doping structures.

PMOS and NMOS

• S: Source

• D: Drain

• G: Gate

• NMOS: Usepositive voltageto control conduction, current flows fromdrain (D) to source (S), suitable forlow-side switch。

• PMOS: UseNegative voltageControls conduction, current flows fromSource (S) → Drain (D), suitable forhigh-side switch。

NMOS transistor

NMOS transistor

d1ea90de-fe61-11ef-9310-92fbcf53809c.jpg

The above figure is a schematic of PMOS. The substrate is N-type semiconductor, and the source and drain are doped with P-type impurities (such as boron B) to form P+ regions. N-type silicon has many electrons.

d1ee6380-fe61-11ef-9310-92fbcf53809c.png

The above figure is a schematic of NMOS. The substrate is P-type silicon, and the source and drain are doped with N-type impurities (such as phosphorus P) to form N+ regions. P-type silicon has many holes.

Reference

[1]

PMOSandNMOSworking principle of

[2]

NMOS and PMOS difference between（Easy to understand）

Reference Bilibili video: