What is a delay locked loop (DLL)?
A DLL is used to generate finely controlled delays that are a fraction of the period of a reference clock. A DLL has the unique property of making these delays independent of operating conditions (i.e. independent of voltage, process variation, temperature, etc.) Unlike PLLs, DLLs can not generally perform frequency multiplication. DLLs are often used in applications such as DDR interfaces, which require synchronous data transmission/recovery.
