Multi-level DRAM?

By: Carson (carson.delete@this.example.edu), January 5, 2021 12:14 pm
Room: Moderated Discussions
Brett (ggtgp.delete@this.yahoo.com) on December 20, 2020 8:07 pm wrote:
> So when does DRAM convert over to multi-level charges like flash storage?

Never.

To all the people talking about 3D stacking of DRAM cells, you're answering the wrong question. Brett was asking about multiple voltage levels storing multiple bits per cell, like MLC, TLC, QLC in flash.

And, to repeat, the answer is never.

Reading a multi-level ROM cell is a sequential process where you try various gate voltages to see where the threshold voltage is. This is straightforward because reading a ROM cell doesn't change the charge in the floating gate and thus the threshold voltage.

Reading a DRAM cell is fundamentally different because reads are destructive. You pick a voltage level, precharge the matched bit lines, then connect the DRAM capacitor to one and let the sense amplifier compare the resultant voltages. It's possible to design a sense amplifier that doesn't cause a refresh, but that wouldn't help, because the DRAM capacitor is discharged and no longer available to read.

You can't compare the voltage at the sense end of the bit line with a static threshold because EMI would kill you. You need to compare two carefully matched and parallel bit lines which pick up disturbances identically. (Most DRAM arrays exchange the bit lines periodically for the full twisted pair effect.)

This doesn't seem likely to be solved without a pretty major redesign of the basic DRAM cell. At which point it won't be DRAM any more. (And we all know how often that's succeeded. MRAM, FRAM, ZRAM, ...)
< Previous Post in ThreadNext Post in Thread >
TopicPosted ByDate
In-band ECC support in recent Atom SoCsGabriele Svelto2020/12/15 03:24 PM
  In-band ECC support in recent Atom SoCsanon2020/12/15 05:40 PM
  In-band ECC support in recent Atom SoCsanon32020/12/15 07:07 PM
  In-band ECC support in recent Atom SoCsEtienne Lorrain2020/12/16 01:48 AM
    In-band ECC support in recent Atom SoCsAdrian2020/12/16 07:43 AM
      ECC in SoCsKonrad Schwarz2020/12/17 07:37 AM
        ECC in SoCsAdrian2020/12/17 08:43 AM
          ECC in SoCsMichael S2020/12/17 12:06 PM
  In-band ECC support in recent Atom SoCs & Tiger Lake UAdrian2020/12/16 07:31 AM
    In-band ECC support in recent Atom SoCs & Tiger Lake UJS2020/12/16 09:07 PM
      In-band ECC support in recent Atom SoCs & Tiger Lake UGabriele Svelto2020/12/16 10:00 PM
        In-band ECC support in recent Atom SoCs & Tiger Lake UJS2020/12/17 12:39 AM
          In-band ECC support in recent Atom SoCs & Tiger Lake UEtienne Lorrain2020/12/17 02:15 AM
            In-band ECC support in recent Atom SoCs & Tiger Lake UJames2020/12/17 07:28 AM
              In-band ECC support in recent Atom SoCs & Tiger Lake UEtienne Lorrain2020/12/17 09:16 AM
                In-band ECC support in recent Atom SoCs & Tiger Lake Urwessel2020/12/17 09:51 AM
                  In-band ECC support in recent Atom SoCs & Tiger Lake UMichael S2020/12/17 12:22 PM
    Enough with the idiocy ... let's have proper ECC again.Björn Ragnar Björnsson2020/12/16 10:09 PM
      Enough with the idiocy ... let's have proper ECC again.Maxwell2020/12/17 12:58 AM
        Enough with the idiocy ... let's have proper ECC again.pixiespeed2020/12/17 09:04 AM
      Enough with the idiocy ... let's have proper ECC again.Adrian2020/12/17 07:40 AM
      Enough with the idiocy ... let's have proper ECC again.Maynard Handley2020/12/17 09:09 AM
        Enough with the idiocy ... let's have proper ECC again.Etienne Lorrain2020/12/17 09:26 AM
          Enough with the idiocy ... let's have proper ECC again.Maynard Handley2020/12/17 09:42 AM
            Enough with the idiocy ... let's have proper ECC again.David Kanter2020/12/17 12:04 PM
              Enough with the idiocy ... let's have proper ECC again.Doug S2020/12/17 01:03 PM
              Enough with the idiocy ... let's have proper ECC again.phonon2020/12/17 03:25 PM
                Internal array ECC vs. memory controllerDavid Kanter2020/12/19 10:39 AM
                  Internal array ECC vs. memory controllerJörn Engel2020/12/20 10:42 AM
                    Internal array ECC vs. memory controllerrwessel2020/12/20 10:52 AM
                    Internal array ECC vs. memory controllerDavid Kanter2020/12/20 03:44 PM
              Enough with the idiocy ... let's have proper ECC again.Maynard Handley2020/12/17 04:55 PM
                Enough with the idiocy ... let's have proper ECC again.rwessel2020/12/17 07:34 PM
                  Enough with the idiocy ... let's have proper ECC again.Maynard Handley2020/12/17 09:10 PM
                    Enough with the idiocy ... let's have proper ECC again.Maynard Handley2020/12/17 09:43 PM
                      Enough with the idiocy ... let's have proper ECC again.Maynard Handley2020/12/18 09:30 AM
                        Enough with the idiocy ... let's have proper ECC again.anon22020/12/19 01:00 AM
                          Enough with the idiocy ... let's have proper ECC again.Maynard Handley2020/12/19 10:23 AM
                            Enough with the idiocy ... let's have proper ECC again.anon22020/12/19 03:01 PM
                              Enough with the idiocy ... let's have proper ECC again.Maynard Handley2020/12/19 04:23 PM
                                Enough with the idiocy ... let's have proper ECC again.anon22020/12/19 04:30 PM
              Enough with the idiocy ... let's have proper ECC again.Björn Ragnar Björnsson2020/12/17 07:41 PM
                Enough with the idiocy ... let's have proper ECC again.David Hess2020/12/19 08:48 PM
              Enough with the idiocy ... let's have proper ECC again.Memory Guy2020/12/17 09:19 PM
      Enough with the idiocy ... let's have proper ECC again.rwessel2020/12/17 10:01 AM
      Enough with the idiocy ... let's have proper ECC again.Wes Felter2020/12/18 09:38 PM
        Thanks for the confirmation!David Kanter2020/12/19 11:51 AM
          Thanks for the confirmation!Konrad Schwarz2020/12/20 09:34 AM
            Thanks for the confirmation!Niels Jørgen Kruse2020/12/20 11:01 AM
              Thanks for the confirmation!David Kanter2020/12/20 03:45 PM
              Thanks for the confirmation!Gionatan Danti2020/12/21 12:50 AM
                Thanks for the confirmation!Niels Jørgen Kruse2020/12/21 09:07 AM
            Thanks for the confirmation!David Kanter2020/12/20 03:42 PM
              Thanks for the confirmation!Foo_2020/12/21 02:01 AM
                Thanks for the confirmation!David Kanter2020/12/21 08:39 AM
            Thanks for the confirmation!Paul2020/12/20 11:29 PM
              Thanks for the confirmation!Michael S2020/12/21 01:00 AM
                Thanks for the confirmation!anon20202020/12/21 01:44 AM
                Thanks for the confirmation!Paul2020/12/22 12:42 PM
                  Thanks for the confirmation!Michael S2020/12/22 02:28 PM
                    Thanks for the confirmation!Paul2020/12/22 06:12 PM
                      Thanks for the confirmation!Michael S2020/12/23 02:55 PM
                        Thanks for the confirmation!Paul2020/12/23 03:54 PM
                          Thanks for the confirmation!Dan Fay2020/12/23 04:38 PM
                            Thanks for the confirmation!Paul2020/12/26 04:10 AM
                              Thanks for the confirmation!Björn Ragnar Björnsson2020/12/26 08:37 PM
                                Thanks for the confirmation!anon22020/12/27 02:00 AM
                                Thanks for the confirmation!Doug S2020/12/28 12:47 PM
            Thanks for the confirmation!David Hess2020/12/21 06:35 PM
              Thanks for the confirmation!Konrad Schwarz2020/12/22 12:08 AM
                Thanks for the confirmation!Doug S2020/12/22 10:42 AM
                  Thanks for the confirmation!David Hess2020/12/22 12:32 PM
                Thanks for the confirmation!David Hess2020/12/22 12:21 PM
        Enough with the idiocy ... let's have proper ECC again.Björn Ragnar Björnsson2020/12/19 04:25 PM
          Enough with the idiocy ... let's have proper ECC again.Brett2020/12/19 08:13 PM
            Enough with the idiocy ... let's have proper ECC again.David Hess2020/12/19 09:17 PM
              Enough with the idiocy ... let's have proper ECC again.Konrad Schwarz2020/12/21 03:29 AM
                Enough with the idiocy ... let's have proper ECC again.David Hess2020/12/21 06:49 PM
            Enough with the idiocy ... let's have proper ECC again.Björn Ragnar Björnsson2020/12/19 09:57 PM
              Enough with the idiocy ... let's have proper ECC again.Björn Ragnar Björnsson2020/12/19 10:14 PM
            Enough with the idiocy ... let's have proper ECC again.Adrian2020/12/20 02:06 AM
              Enough with the idiocy ... let's have proper ECC again.rwessel2020/12/20 08:43 AM
             Multi-level DRAM?Brett2020/12/20 08:07 PM
               Multi-level DRAM?Heikki Kultala2020/12/21 11:58 AM
               Multi-level DRAM?David Hess2020/12/21 07:25 PM
                 Multi-level DRAM?Adrian2020/12/22 05:15 AM
                   Multi-level DRAM?Dan Fay2020/12/22 10:11 AM
                     Multi-level DRAM?Paul2020/12/22 06:01 PM
                       Multi-level DRAM?Dan Fay2020/12/23 12:29 PM
                         Multi-level DRAM?Paul2020/12/23 01:00 PM
                           Multi-level DRAM?Dan Fay2020/12/23 04:30 PM
                             Multi-level DRAM?David Hess2020/12/23 05:05 PM
                           Multi-level DRAM?Björn Ragnar Björnsson2020/12/25 06:44 PM
                             Multi-level DRAM?Paul2020/12/26 04:04 AM
                               Multi-level DRAM?Michael S2020/12/26 08:11 AM
                                 DIMM binsPaul2020/12/26 08:55 AM
                                   DIMM binsBjörn Ragnar Björnsson2020/12/26 08:09 PM
                                     DIMM binsBjörn Ragnar Björnsson2020/12/26 08:19 PM
                                       DIMM binsDaniel Fay2020/12/27 07:51 PM
                                  Is binning at the module or die level? (NT)anonymous22020/12/27 02:36 PM
                                    Is binning at the module or die level?David Hess2020/12/28 01:31 PM
                               Multi-level DRAM?Doug S2020/12/28 12:55 PM
                               Multi-level DRAM?David Hess2020/12/28 01:36 PM
                             Multi-level DRAM?anon­­32020/12/26 10:22 PM
                               Multi-level DRAM?Björn Ragnar Björnsson2020/12/27 07:12 PM
                               Multi-level DRAM?Paul2021/01/04 04:20 AM
               Multi-level DRAM?Carson2021/01/05 12:14 PM
                 Multi-level DRAM?Brett2021/01/05 02:05 PM
        Enough with the idiocy ... let's have proper ECC again.Björn Ragnar Björnsson2020/12/19 04:35 PM
        Enough with the idiocy ... let's have proper ECC again.David Hess2020/12/19 08:59 PM
          Enough with the idiocy ... let's have proper ECC again.rwessel2020/12/20 08:56 AM
          Enough with the idiocy ... let's have proper ECC again.Doug S2020/12/20 10:16 AM
Reply to this Topic
Name:
Email:
Topic:
Body: No Text
How do you spell tangerine? 🍊