skywater-pdk/docs/rules/device-details/esd_nfet/index.rst

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NMOS ESD FET
------------
Spice Model Information
~~~~~~~~~~~~~~~~~~~~~~~
- Cell Name: :cell:`sky130_fd_pr__nfet_01v8`
- Model Name: :model:`sky130_fd_pr__esd_nfet_01v8`, :model:`sky130_fd_pr__esd_nfet_g5v0d10v5`, :model:`sky130_fd_pr__esd_nfet_g5v0d10v5_nvt`
Operating Voltages where SPICE models are valid
- V\ :sub:`DS` = 0 to 11.0V (:model:`sky130_fd_pr__nfet_g5v0d10v5*`), 0 to 1.95V (:model:`sky130_fd_pr__nfet_01v8*`)
- V\ :sub:`GS` = 0 to 5.0V (:model:`sky130_fd_pr__nfet_g5v0d10v5*`), 0 to 1.95V (:model:`sky130_fd_pr__nfet_01v8*`)
- V\ :sub:`BS` = 0 to -5.5V, (:model:`sky130_fd_pr__nfet_g5v0d10v5`), +0.3 to -5.5V (:model:`sky130_fd_pr__nfet_05v0_nvt`), 0 to -1.95V (:model:`sky130_fd_pr__nfet_01v8*`)
Details
~~~~~~~
The ESD FETs differ from the regular NMOS devices in several aspects, most notably:
- Increased isolation spacing from contacts to surrounding STI
- Increased drain contact-to-gate spacing
- Placement of n-well under the drain contacts
Major model output parameters are shown below and compared against the EDR (e-test) specs
.. include:: esd_nfet-table0.rst
The symbols of the :model:`sky130_fd_pr__esd_nfet_g5v0d10v5` and :model:`sky130_fd_pr__esd_nfet_g5v0d10v5_nvt` (ESD NMOS FET) are shown below:
|symbol-esd_nfet_g5v0d10v5| |symbol-esd_nfet_g5v0d10v5_nvt|
The cross-section of the ESD NMOS FET is shown below.
|cross-section-esd_nfet|
.. |symbol-esd_nfet_g5v0d10v5| image:: symbol-esd_nfet_g5v0d10v5.svg
.. |symbol-esd_nfet_g5v0d10v5_nvt| image:: symbol-esd_nfet_g5v0d10v5_nvt.svg
.. |cross-section-esd_nfet| image:: cross-section-esd_nfet.svg