Neven,
I have tested many SDRAMs and have seen quite a difference between
manufacturers. 3 dB is not uncommon in my experience. I think you will have to
obtain parts from different manufacturers and try them out. Some Samsung parts
appear to employ output driver edge shaping for EMI reduction.
Dave Cuthbert
Linear Technology
_____
From: [email protected] [mailto:[email protected]] On Behalf Of
[email protected]
Sent: Friday, February 09, 2007 2:20 PM
To: [email protected]
Subject: Best SDRAM for Low-Emission?
Hello everyone,
I have a 2-layer PCB design, plastic enclosure, using 120 MHz SDRAM, two
stuffing options: 2MB (16 Mb) in 50-pin tsop package or 8MB (64 Mb) in 52-pin
tsop.
It is slightly above class B radiated emission at the multiples of 120 MHz. I
troubleshot it and I determined the SDRAM is the only source of the failing
frequencies, everything else is quiet.
I wonder if anyone has looked in how various manufacturers' memory chips
perform emission-wise, particularly the type that I am using. I hope to find a
manufacturer who makes "quieter" modules, so I do not need to change anything
else on my board.
If anyone has done such a comparison/investigation, I would appreciate if you
would be willing to share, on-line or off-line, the results - which
memory/manufacturer works best EMI-wise in such conditions.
Regards, Neven
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