Help me overcome problems with reading data from DDR IO

[neyee]

I design a ddr1 io in our chip, when I read data from memery with parallel terminations resistor the result is OK, the trace on pcb is about 6 inch(15cm),but
when I take off the parallel terminations resistance and only left the series resistor, I find I can't read right data from the memory chip, I think it is because of reflection, I want to know if I put the memory chip closer to our chip and only with series resistor, Can the ddr io work succesfully? How can simulation this?
thanks very much for your answer!!!

 

[chekunidze]

ddr io

for what you take off terminators?

if I put the memory chip closer to our chip and only with series resistor, Can the ddr io work succesfully...

50/50
because - long-transmission line, when (net length) >> (signal wave lengh),
and what tells specification of DDR about terminations?

look on attach, for example

 

[neyee]

Re: about DDR io design

Thank you very much , according to system cost so we need take off the parallel resistor

 

[dhawalkadao]

Re: about DDR io design

Thank you very much

 

[sigint]

Re: about DDR io design

Muntzing, gone crazy - the resistors save you about .5 Euro.

SiGiNT