Industry Expert Blogs

As a provider of DDR PHY and controller IP, the question we get asked the most goes something like this: “Will your PHY support a {insert short description of system here} at {fill in the speed here} Mbps? Lately, I am receiving a lot of questions around DDR4 such as “Will your DDR4 PHY support one dual rank UDIMM at 2667Mbps”?

Unfortunately, the answer is never what someone wants to hear. The answer is usually “It depends”. For example, DDR4 at 2667Mbps is a very high data rate for a parallel, single ended, 72-bit channel populated with 2 ranks of 4-bit wide SDRAMs. That is a load of 2 SDRAMs per bit of data and 36 SDRAMs on the address/command bus! That’s why RDIMMs and LRDIMMs were invented – to isolate the address/command (RDIMM) and data (LRDIMM) loading from the channel.

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