Can I make a device fabricated in a nm process behave like

a long channel device by making L several microns in length

or even longer? I want to make my devices follow the square-

law equations.

 

Nanometer devices are designed to drop the drain-source voltage

across a very small distance (see pages 144 and 151 in the 3rd

edition concerning dVDS/dXdl). Increasing the channel length

simply increases the amount of inverted charge under the gate

oxide adjacent to the source, Fig. 6.10. Longer channel length

does not significantly change the width of Xd in Fig. 6.10 and

thus short-channel effects (e.g., velocity saturation) are still

present.

 

As mentioned throughout the book devices fabricated in submicron

CMOS process do not (even remotely) follow the square-law

equations and that is why we donít use them when we design in

nm CMOS processes.

 

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