open-source-silicon.dev

sonos_magic.png

sonos_cross.png

Hello!
I have some questions regarding the sonos cell.

1. In readthedocs there are schematic for 2-T sonos cell. However, in magic sonosfet_star instantiation shows only one device. Is there any script available to generate 2-T sonos cell in magic?
2. If I want to use the 1-T sonos cell currently available in magic as 2-T cell, is there any specific choice of device (regualr, nvt, lvt?) that need to need to use as the second fet?
3. I cannot seem to instantiate the sonos cell in magic without the guard ring. Is it a must for the sonos cell?


The failure to generate a SONOS cell without a guard ring was an error in the PDK script, and I just tracked down the problem and fixed it.  (pushed to open_pdks master branch on <http://opencircuitdesign.com|opencircuitdesign.com> and will update the github mirror overnight.)

<@U01BVA014EN>:  The 2nd device in the illustration is type "npass".  I should break out the SRAM-specific FET types into their own category and include the devices npass, npd, ppu, etc.  You can create such a device by hand by drawing poly over diffusion, then drawing type "npass" over the existing gate to change the type.  Note that "npass" has a specific device width and length;  I would have to look up the existing netlist or layout to remember the dimensions.  It is essentially a standard nFET but with a special device model for the specific W and L used in the SRAM cells.