Why PLL is used instead of DLL for DDR?

[prashantbabu]

Hi folks,
I have a basic question regarding PLL clock drivers for DDR applications.
Why is it that PLLs are used when a DLL can accomplish the same function.
Since we are not multilpying the input frequency and we are just buffering the input clock to many output channels, I think that a DLL should do just fine rather than a PLL.
Can anybody please clear my doubt?
Thanks in advance!

 

[roli]

PLL vs. DLL for DDR

Please, first explain the differences (and trade-offs) between PLL & DLL, especially in terms of practical implementations in full customed CMOS process.