transistor width and pvt variations

[midhs]

how transistor width is affected by pvt variations

if two transistors, which have different widths, is fabricated
both transistors are placed close to each other so process variation can be negletted.
voltage and temperature variations will affect the transistor in same way becuase they are close to each other.

but the change in the tractoristics will be same?
will delays of those transistor will remain in the same ratio as before?

please help me

 

[artmalik]

The transistor width is only impacted by process and NOT voltage/temperature. Width is a physical thing which will be the same. Voltage and temperature effect the performance of the device because the mobility of carriers depends on voltage and temperature etc.

Placing two devices close to each other means the other parameters like optical effects,oxide thickness, dopant implants will match each other because of physical proximity. A simple text book equation of Id= k(vgs-vt)2 equation will tell you the impact. k=uWCox/L .... mu,W,L,Cox will depend on how the transistor is fabricated.....

so if Id changes the delay changes ....

how transistor width is affected by pvt variations

if two transistors, which have different widths, is fabricated
both transistors are placed close to each other so process variation can be negletted.
voltage and temperature variations will affect the transistor in same way becuase they are close to each other.

but the change in the tractoristics will be same?
will delays of those transistor will remain in the same ratio as before?

please help me

 

[midhs]

thank you

let me clear my question once again

because of temp and volt the delay changes
is the amount of change same for two transistors having same width?

 

[Prashanthanilm]

thank you

is the amount of change same for two transistors having same width?

Yes, It is almost same. Also depends upon whether the Transistor is nMOS or pMOS. Since they have different mobility their variation changes.

But for the same MOS, the variation are almost similar provided they are not too far placed to each other.

 

[yadavvlsi]

I think smaller transistor will have more variation.

 

[midhs]

thank you everyone

sorry for the late response

can you pls refer a book dealing with pvt variations

 

[Prashanthanilm]

This will help you to understand the variations better (Need not give you direct answer )

Hope this Helps!!