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Magic Mailing List |
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From: Stefanos Sidiropoulos (stefanos AT rambus DOT com) Date: Wed Apr 05 2000 - 17:58:57 EDT
> maybe i've misunderstood you. what i'm talking about is that, if you You indeed misunderstand me... > look at the attached .mag file with a non-silicided process techfile, > like SCNA.80.tech27, the wells labelled 'pw' and 'nw' will *not* be > connected to gnd and vdd, respectively, since there will be n+/p+ > junctions between the transistor diffusions and the ohmic diffusions > (well-contacts). however, if you use a silicided process techfile, > like SCN3M_SUBM.30.tech27, you will see that the wells are connected > to their respective supplies, since the silicide removes those n+/p+ > junctions, reflecting the fabricated part. it may be a "weak" > connection but it doesn't have to carry much current (hopefully) to > keep the wells biased. however, how can i make this clearer, it's NOT > weak! > Now take a look on the attached magic file (which is the same as yours with just a slight change). I am not saying that a designer would do that willingly but the point of extraction/LVS/simulation is to catch such mistakes. However, your SCN3M_SUBM.30.tech27 will happilly say that the source of the PMOS is connected nicely to vdd. You can argue that this particular cell might work but a similar connection can carry a LOT of current and definitely is VERY WEAK. Hope that is clear now. -- Stefanos magic tech scmos timestamp 954970860 << pwell >> rect 3 0 19 24 << nwell >> rect 3 24 19 48 << polysilicon >> rect 4 34 9 36 rect 13 34 15 36 rect 4 26 6 34 rect 4 14 6 22 rect 4 12 9 14 rect 13 12 15 14 << ndiffusion >> rect 9 14 13 15 rect 9 11 13 12 << pdiffusion >> rect 9 36 13 41 rect 9 33 13 34 << metal1 >> rect 0 41 9 45 rect 13 41 19 45 rect 9 26 13 29 rect 9 22 17 26 rect 9 19 13 22 rect 0 7 9 11 rect 13 7 19 11 rect 0 3 19 7 << ntransistor >> rect 9 12 13 14 << ptransistor >> rect 9 34 13 36 << polycontact >> rect 2 22 6 26 << ndcontact >> rect 9 15 13 19 rect 9 7 13 11 << pdcontact >> rect 9 29 13 33 << nsubstratencontact >> rect 9 41 13 45 << psubstratepdiff >> rect 9 3 13 7 << labels >> rlabel metal1 6 7 6 7 2 gnd:1 rlabel metal1 6 41 6 41 4 vdd:1 rlabel pwell 17 18 17 18 7 pw rlabel nwell 17 29 17 29 7 nw << end >>
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