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How does DDR4-2400 (I/O Clock as 1200MHz) achieve higher data rate of 2.4 GT/s when memory clock is only 300MHz and the data width is limited to 144 bits on an Arria10 device?

SKGR0
Beginner
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3 Replies
Deshi_Intel
Moderator
176 Views

Hi,

 

DDR4 bandwidth calculation = DDR4 memory clock frequency x 2 x total DQ width

 

For instance, using your example

DDR4 BW = 300MHz x 2 x 144 = 86.4MT/s

 

I am not sure how does the 2.4GT/s calculation comes from

 

Thanks.

 

Regards,

dlim

SKGR0
Beginner
176 Views

Thanks.

 

I had found the below details in the Wikipedia Page https://en.wikipedia.org/wiki/Double_data_rate

DDR4-2400, PC4-19200

Memory Clock - 300MHz

I/O Bus Clock - 1200MHz

Transfer rate - 2.4GT/s

Theoretical Bandwidth - 19.2GB/s

 

How were these numbers derived?

 

Deshi_Intel
Moderator
176 Views

2.4GT/s Transfer rate =1200MHz x 2

 

19.2GB/s Theoretical Bandwidth = (1200MHz x 2 x 64 bit DQ) = 153.6Gb/s = 19.2GB/s

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