| --- Mon Jun 17 2013 | 00:00 | |
| berndj | http://vlsitechnology.org/html/cells/vgalib013/iv1.html those gates on the far right of each of those cells don't seem to be connected to anything; what's up with that? | 17:27 |
|---|---|---|
| Action: azonenberg looks | 18:48 | |
| azonenberg | Which cells? | 18:48 |
| azonenberg | oh, hmm | 18:48 |
| azonenberg | No | 18:48 |
| azonenberg | They're connected to the power rails | 18:48 |
| azonenberg | for cell-to-cell isolation, forcing the transistors off | 18:48 |
| berndj | azonenberg, you reckon those cells are intended to abutt so the diffusion regions coalesce? | 19:14 |
| azonenberg | Yes | 19:14 |
| azonenberg | And if so, that's the inter-cell isolation | 19:14 |
| azonenberg | Rather than STI they're doing always-off transistors | 19:14 |
| berndj | i can see the rail connections to poly in the zoomed in view now - http://vlsitechnology.org/alliance/gif/vgalib013/iv1v0x2.gif | 19:15 |
| berndj | STI? | 19:15 |
| azonenberg | Why they have those big flags hanging off the side is unclear to me | 19:15 |
| azonenberg | over the wells, i mean | 19:15 |
| azonenberg | That is also a rather unusual isolation design | 19:16 |
| berndj | yeah, if the diffusion regions would connect, then those poly flags would connect too? | 19:16 |
| azonenberg | Hmm | 19:16 |
| azonenberg | good point, i wonder whats up with that | 19:16 |
| berndj | my first though was that the author was being lazy and made all the diffusion regions the same, and then just changed the routing to get different drive strengths | 19:16 |
| azonenberg | In any case the SecurID has space between diffusions | 19:16 |
| azonenberg | which is the more conventional cell structure i see | 19:16 |
| azonenberg | it's a beautiful 1um 2-metal standard cell chip | 19:17 |
| berndj | in http://vlsitechnology.org/alliance/gif/vgalib013/iv1v0x4.gif you can actually see how everything's the same except metal and contact, and the left gates connect to the right gates through a link under the Vdd rail | 19:17 |
| azonenberg | Interesting | 19:17 |
| berndj | is there any reason to treat intra-cell elements as anything other than lumped? if a cell is only a few microns wide, would you have to care about transmission line effects only at ridiculously high frequencies? | 20:54 |
| berndj | practically infrared in fact? | 20:55 |
| Sync_ | meh. | 23:38 |
| Sync_ | I guess that counts as a failure | 23:38 |
| Sync_ | back to the drawing board it is I guess. I probably need linear ball bearings | 23:46 |
| --- Tue Jun 18 2013 | 00:00 | |
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