By Scott Schaefer, Micron Technology
Embedded.com (11/25/08, 03:40:00 PM EST)
DDR2/DDR3 Functionality
Up to this point, the discussion started in Part 1 has focused on clock jitter in terms of a DRAM's functionality as opposed to it working correctly; there is a subtle but important difference. DDR2/DDR3 clock jitter specifications are applied to input timings only; output timings are stated without any clock jitter and any clock jitter effects must be added to them.
Suffice it to say that there is a reasonably good explanation why this became the industry-standard methodology. Thus, clock jitter analysis needs to be separated between input timings concerns (will the device function correctly?) and output timing concerns (will the data eye be big enough?)
Embedded.com (11/25/08, 03:40:00 PM EST)
DDR2/DDR3 Functionality
Up to this point, the discussion started in Part 1 has focused on clock jitter in terms of a DRAM's functionality as opposed to it working correctly; there is a subtle but important difference. DDR2/DDR3 clock jitter specifications are applied to input timings only; output timings are stated without any clock jitter and any clock jitter effects must be added to them.
Suffice it to say that there is a reasonably good explanation why this became the industry-standard methodology. Thus, clock jitter analysis needs to be separated between input timings concerns (will the device function correctly?) and output timing concerns (will the data eye be big enough?)