Hello! I have some questions regarding the sonos c...
# sky130
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?
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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 opencircuitdesign.com and will update the github mirror overnight.)
@Md Munir Hasan: 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.