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When SDRAM is manufactured, how do they integrate logic into the IC while they are using a DRAM process for fabrication?
Because SDRAM requires logic to decode its inputs, do the burst ordering, etc. (DRAM too - though it has less logic)

Saad
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  • Why do you think this would be a problem? Regular DRAM has that kind of logic, too. – Dave Tweed Dec 10 '12 at 05:02
  • But I still don't get how they integrate logic into a DRAM process - I've read a CMOS VLSI book, and it says it's not possible to put logic on a DRAM process. – Saad Dec 10 '12 at 05:14

1 Answers1

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... get a better VLSI book?

It's possible; it's just not optimal. Logic processes are designed for speed; they go to great lengths to avoid stored charge, adjusting doping, bias voltages etc to clear it away as fast as possible.

Since stored charge is rather important to DRAM, the DRAM process is tuned in a different way!

Thus while a fast logic process may be able to run faster than 2GHz, logic on a DRAM process is perfectly possible, but its speed may be restricted to the 0.5-0.8 GHz region.

  • +1. Several people have fabbed a CPU and a DRAM on the same chip, using a standard "DRAM process" -- [computational RAM](http://en.wikipedia.org/wiki/computational_RAM). Therefore, it must be possible. – davidcary Dec 10 '12 at 14:42