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Length matching the DQS signal with clock signal in DDR2

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venkat_kode

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ddr2 length matching

Hi all,

Can any body explain the skew relationship between DDR2 Clock signal and DQS signal.

Is there any length matching requirement for these two signals?
 

dqs signal for ddr2

Hi,

In DDR2 routing, u have to 3 types of lines

Databyte lanes
Address and command lines
Clock lines

Each databyte lane include 8 databits(DQ0:7), 1 DataMask(DM0), 1 Data strobe(DQS0).
For a single byte lane, u should consider DQS as the clock and route them with 100mils tolerant length matching. like wise, u do for all the bytelanes.

Route address and command lines with length matching with 100 mils matching tolerance.

route clock as separate with 20mils matching betwwn the differential pairs.

There is no need to match the DQS and clock lines.

Regards,
sandhya
Route
 

ddr2 dqs and clock skew

Hi ......

I am working on a motherboard...

and found that there should be only 25 mils mismatch between data lines and DQS0

and DQM0.
 

from dqs to clock

pcb87 said:
Hi ......

I am working on a motherboard...

and found that there should be only 25 mils mismatch between data lines and DQS0

and DQM0.

How much length difference u have between DQS and Clock
 

routing lanes ddr2

In my design, according to the guidelines clock length is between 2 inch and 7 inch.
and i routed all the colock signals as differntial pairs in 80mm length.
I think there is no need to match the length of the clock signals and the DQS and DQM..
these are routed with MD[0:7] data lies.
and mismatch should be less than 25 mils.
 

ddr2 routing lenghth

hi pcb87 r u using SODIMM or Discrete components?
 

relation between dqs and clock in ddr2

I am using DDR2 DIMM.
 

ddr2 clock

hi i am simulating ddr2 clock in hyperlynx but the ibibs model of soc is single neded.Is it copulsary that clock should be diferential.\and also the clock is not coming proper.
 

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