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#sky130
Title
# sky130
c

Connie Duong

03/03/2022, 7:25 AM
Sorry if this is a really basic question, but is it possible to separate the body and attach it to different nodes? I see in the device details website (https://skywater-pdk.readthedocs.io/en/main/rules/device-details.html#v-nmos-fet) that there is a DNW for the pwell to be isolated, but it says that is optional. How do I specify this? When I use the 4 terminal symbol in xschem to generate the spice file, I can separate the body nodes, but when I regenerate the spice file in magic, the body nodes seem to always be tied to together? Is there an extra step I need to do in magic?
a

Arman Avetisyan

03/03/2022, 9:24 AM
You need to use deep nwell. It is used to isolate two pwell bulks from each other. Take a loot at:https://github.com/armleo/armleo_gpio/blob/main/gds/user_analog_project_wrapper.gds.gz It contains a armleo_gpio module which has two power domains with dnwell. You can use it as reference. Pay attention to nwell and dnwell.
🙌 2
You use taps to connect to nwell. Nwell can be used to connect to dnwell. Dnwell had to have certain distance from another dnwell
"inside" is the pwell which is connected to ground and the nwell is connected to vdd. This creates a closed diode, which is used for isolation purposes.
Google: deep nwell and take a look at pictures. Pictures may help you visualize
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Connie Duong

03/03/2022, 6:08 PM
@User thanks so much for the clarification!