Survey and Analysis of Delay-Locked Loops Used in DRAM Interfaces

Memory Interfaces: Past, Present, and Future

“…Because tAC is a function of process, voltage, and temperature (PVT), READ data availability at the memory-control unit (MCU) exhibits both static and dynamic variability. When the MCU attempts to capture all incoming data bits simultaneously, the valid data window disappears and causes a failure to capture the data without DLL for removing the tAC variation, as described in Figure 3; the conceptual block diagram of clocking with DLL is shown in Figure 4 [6], [7].…”