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What is the meaning of the following sentence:

Simulate a Unit Size NMOS (W=5 * 325nm/L=5 * 65nm) and PMOS (W=5325nm/L=565nm) with in CMOS technology.

Well, this transistor is a MOSFET with 65nm feature size. The multiplier "5*", is vague for me. Does it mean to give value of 5 to "finger" and "multiplier" parameters?

mohammad rezza
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1 Answers1

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A unit transistor is usually just a certain W/L ratio that makes the design flow easier.

The current gain of a transistor is proportional to W/L, so you can then say "2 times the unit transistor" to indicate "2*W/L", without having to say the length of the transistor per se, which is often used to design other properties of the circuit (e.g. output impedance in amplifiers).

In order to avoid short-channel effects for characterizing this "unit transistor", we do not want to use the shortest possible transistor, hence the factor 5 in both W and L (which means that W/L doesn't change and still represents a "unit transistor").

Sven B
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