What is the effect of varying the gate length in both AC and DC characteristics?

[protonixs]

In CMOS, what is the effect of varying the gate length in both AC and DC characteristics?
Does it affect the current-carrying capacity of the device?

Thanks and regards,
protonixs

 

[A.Anand Srinivasan]

Re: gate length

it affects and we all the know that drain current is inversely proportional to length... but in fabs the length is generally a fixed value... it affects the AC and DC parameters because change in length changes the capacitance and resistance too...

 

[pichuang]

gate length

This is my little 2 cents.

The drain current is proportional to the W/L ratio. Therefore, it is a better practice to just adjust one parameter, and i guess the common practice is to keep L at minimum level and adjusting W accordingly.

varying the gate length will definitely change the AC and DC characteristic. I do not have any references with me at this moment so I can't provide any details about it.

Back to your problem, I think the answer is Yes, it will affect the current-carrying capacity of the device

Hope that helps,

 

[lijianheng]

Re: gate length

For DC affect Vdsat, for AC affect gm, rds.

 

[protonixs]

Re: gate length

leaving a constant W, increasing/reducing the gate length reduces/increases the current that flows from source to drain, is that right?

 

[A.Anand Srinivasan]

Re: gate length

ya.... you are right...