How do I calculate the drain length Ld of a nmos/pmos? In BSIM3V3, there is no parameter Ld.. Can anyone suggest what I can do?
Thanks, Megs.
How do I calculate the drain length Ld of a nmos/pmos? In BSIM3V3, there is no parameter Ld.. Can anyone suggest what I can do?
Thanks, Megs.
Thanks for your reply, Kevin.
Here, in the formula given above, L stands for length of the channel.. What I am trying to find out is the length of the drain (or source) so that I can find the area and perimeter of the drain (and source) ..... In the tool LTSpice, I have to enter the area and perimeter of the drain so that the tool can calculate the capacitances.
Meghana.
Look up HDIF. Generally AD, AS, PD, PS, NRD, & NRS are all calculated from L, W & HDIF.
...Jim Thompson
-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | | http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
Thanks for replying, James. But here is no HDIF in LTspice (Swcad III)...
Meghana.
It's in the device model.
...Jim Thompson
-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | |
Width and length are user specified values. They are specified on the net list line, e.g.
m1 1 2 3 nmos L=1.2u W=15u
Some spices (e.g SuperSpice) allow these parameters to be set on the schematic via the GUI.
Ball park values for L and w are often designed from:
I=K.W/L(Vg-Vt)^2
More often, one just runs the sim a few times till the numbers are what you want:-)
Kevin Aylward snipped-for-privacy@anasoft.co.uk
Yes I missed that point of the post. I have the formulas for the above in my SS help file. Of course, in SS you don't need to, its all automatic!
Kevin Aylward snipped-for-privacy@anasoft.co.uk
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