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Modeling >> Semiconductor Devices >> v*???
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Message started by naren on Jun 23^rd, 2004, 5:51am

Title: v*???
Post by naren on Jun 23^rd, 2004, 5:51am

In EECS240 by Prof.Boser....can some one tell me what is V* as a function of Vgs?

Long channel:
V*=VGS-Vth

Short channel:
What is relation between V* and VGS-Vth?

Please tell me the mathematical relation betwen V* and VGS-Vth

If I want to set V*=say ...200mV then what am I supposed to set VGS-Vth=?

Title: Re: v*???
Post by gndod on Jul 8^th, 2004, 5:48am

Hi,
I'm not sure if I get you right because I didn't read your reference...but as war as I know the Vgs-Vth is the "excess gate voltage" of a MOSFET device.
So if this is the case if you wnat V* to be 200mV and if Vth is 300mV, you need to set the Vgs=500mV...
You can find more information in Allen Hambley's book "Electronics", chapter 5.
For short-chanel fet I think that there is a scaling coefficient in the equation but I don't know exactly. You can use as a reference Behzad Razavi's book "Design of analog CMOS Integrated Circuits", chapter 14.

Hope this helps!

Gergana