Darío San Martín Molina02/17/2022, 10:20 PM
), and from there I gathered minimum width & length for the nfet_01v8 were 0.36um/0.15um. My circuit needs small devices to minimize capacitance on certain nodes for high speed, so I set some devices in my schematic to that size, and it simulated without issues. I designed & verified (pre-layout) my circuit with those dimensions, but then when I get to the layout stage, Magic says that "Mos width must be >= 0.42 um" for that device... And it won't let me draw a 0.36um wide device. Why is there this inconsistency between Magic and the Sky130 model files? Which one is correct/to be trusted? Thanks
Tim Edwards02/17/2022, 10:41 PM
length is only approved by SkyWater for use in the SRAM cells, where the density and regularity of the array allow for considerably smaller devices. Magic's device generator follows the guidelines for devices outside a standard cell or SRAM core cell. If you use such a device you will be adding risk to your design, as the device behavior is likely to be considerably off from the model. However, such a device does not violate any manufacturing rules, so you are free to experiment with it. In magic, you would need to draw the layers by hand rather than use the parameterized device generator, since the parameterized device generator will enforce the regular DRC rules.
Stefan Schippers02/17/2022, 10:50 PM
Tim Edwards02/17/2022, 11:02 PM
Stefan Schippers02/17/2022, 11:30 PM
Darío San Martín Molina02/18/2022, 8:48 AM
notice from Magic? I don't think it's even a DRC, it's a message that appears on Magic's command console as soon as I click "Apply" on the params window for that device when trying to enter 0.36um width. And Magic won't even draw the 0.36um device, it just closes the form and sets the device back to 0.42um width.
"Mos width must be >= 0.42 um"
Tim Edwards02/18/2022, 1:59 PM
Darío San Martín Molina02/19/2022, 10:35 AM