Re: DRAM output IV curves

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Greg,

we have done this succeessfully with a simple test fixture which had an
oscillator on it to keep the data refreshed. You don't have to refresh the
whole array, it is enough to repetitively read from the same cell while you are
curve tracing. If you are reading for about 14.5 us and then let go for 0.5 us
and repeat this forever, the (slowly sweeping) curve tracer will not notice
anything. You can build this circuit so that you can write first a zero or one
into the cell and then just read it forever.

Arpad
===============================================================================

Does anyone have experience trying to extract output IV curves from
DRAMs in the lab? This seems like a tough nut to crack since DRAMs lose
their data unless you throw refresh patterns at them continuously. I
haven't actually tried to do this myself, but I would guess you could
get the pull-down curve all right since the memory cells should default
to a zero state if you don't refresh them. To get the pull-up curve,
you have to get your curve tracer to work in conjunction with a pattern
generator.

It sure would be nice to have some way of jamming the outputs to make
these measurements...

----------
Greg Edlund , Principal Engineer
Alpha Server Signal Integrity
Digital Equipment Corp.
129 Parker St. PKO3-1/20C
Maynard, MA 01754
(508) 493-4157 voice
(508) 493-0941 FAX
edlund@eng.pko.dec.com

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Subject: DRAM output IV curves
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