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Can anyone guide me how can we make layout of resistor in magic with sky130 pdk, considering 'ndiffr...
# magic
d
Can anyone guide me how can we make layout of resistor in magic with sky130 pdk, considering 'ndiffres' or 'pdiffres' or' ppolyres' or 'npolyres'? Out of these available res layers which one is a good choice?
a
Use magic to generate the resistor you want. Use their characteristics to determine which one is better in sky's docs
Some have better stability over pvt others have better density
t
Avoid using diffusion resistors (ndiffres, pdiffres) unless you are certain that your circuit keeps the diffusion firmly reverse-biased at all times, and can tolerate the diode leakage. The best choice is the high-sheet-rho poly, if you need a resistor in the range of several kohms and upward. Choose the type so that the resistor isn't too short---if you get below an aspect ratio L:W of, say, 10:1, then proportionally more of the resistor is in the contacts, and the total resistance will be more variable, less accurate, and less well matched between similar layouts.
d
okay thanks @User @User
@User, I tried to make resistor using 'res0p69'' layer then 'ppolyres'on top of it. Due to large length of poly taken, i tried to make it in snake style. But in case of snake style it shows drc error as shown in image, we can't draw bends in poly res.
t
Sorry, that's my fault in interpreting rule poly.11. You can ignore the DRC error. I will correct the magic tech file.
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There is also a rule for distance between precision resistors that is incorrect. I took a conservative approach to the rules while I was still trying to understand them.
d
okay, that sounds good..
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