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Altera_Forum
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18 years ago

Cyclone3-Overshoot/Undershoot

Hi, After PCB Design CIII – EP3C40 based board, in the post routing SI Simulation we are getting some overshoots and undershoots in DDR Signals and LVDS (As receiver) signals. As we are using DDR1 s...
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Altera_Forum
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17 years ago

Looks like you went a bit over the top with your trace length matching, but didn't control the trace spacing of your differential pairs so well. A small change here can create some nasty mismatches.

If I had to do terminators like this I'd be tempted to use 0402 surface mount resistors on the back of the BGA. You can make this work by shaving the corners off the pads (making them octagonal) and still have the pads fit in between the BGA ball breakout VIAs.