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Altera_Forum
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14 years ago

DDR Reflection Phenomenon

Hi everybody, These days I have been asking some questions in relationship with some problems in a new pcb design and the communication between the Cyclone III and the DDR. Finally I think I ha...
Altera_Forum's avatar
Altera_Forum
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14 years ago

Yes, I use series resistors of (25 ohm) and a pull up to (vccio/2) resistor of 56 ohm. These lines belongs to the addresses signals from the FPGA to the ddr-sdram. I attach the schematic and the pcb. The PCB characteristics are: 16 mil layer thick, fr4, cupper 1.4mil, 8mil track thick, 2850 x 2820 mil .

I use a high impedance oscilloscope probe with an input impedance of 1 Mohm shunted by 20 pF .