What is the minimun channel length for a CMOS transistor

[Advark]

Hi, can anyone tell me what the minimun channel length for a MOS transistor for AMS 0.35um process, and why follow the LAMBDA rule for width and length for cmos transistor.

 

[ytliang]

If u are using it for low voltage design, I would think 0.35um would be your minimum length??

 

[jecyhale]

Hi, can anyone tell me what the minimun channel length for a MOS transistor for AMS 0.35um process, and why follow the LAMBDA rule for width and length for cmos transistor.

Usually, 0.35um is the minimum length which is detemined by the process.

 

[drDOC]

why follow the LAMBDA rule for width and length

This is mostly layout related. Many conpanies work with a lambda. Minimum lenght is then usually 2 lambda. An designers should always use integer lambda values.

If a newer process comes around you would be able to take the old design and map it onto the new process. This trick usually doesn't work with analog circuits but digital libraries could be mapped from one process to the other. Well at least that's the idea.

Another thing is that layout engineers only see the lambdas and that makes work easier for them. It is easier to always work with a metal spacing of 2 lambda instead of working with a metal spacing of 1um and 0.26um in another project.

 

[k_90]

0.35 u would be the smallest transistor length.

 

[Advark]

ok, is Lmin= 0.35um and using the lambda rule, Lmin=2Lambda => Lambda=0.35um/2 that would be correct, right ?.
This for layout. The thing is i design a circuit who has all the transistor using the minimun length, why because is for high frequency operation.

 

[Loktik_Vitalij]

>>ok, is Lmin= 0.35um and using the lambda rule, Lmin=2Lambda => Lambda=0.35um/2 that would be correct, right ?.

this is correct
>>The thing is i design a circuit who has all the transistor using the minimun length, why because is for high frequency operation.

for the minimum length of channel - maximum the deviation of the parameters
for the example - NMOS Idsat mismatch

 

[wanghs1986]

0.35u