US Patent 7236411 Programmable memory access parameters

A programmable device can configure memory access parameters to optimize the performance of one or more of its memory units. A memory unit includes one or more programmable delay units connected with clock, control and/or data signals. The configuration data of the programmable device specifies delay values for each programmable delay unit. A programmable delay unit includes at least two signal paths having different timing characteristics. A switching circuit controlled by configuration data is used to select one of the signal paths as the output of the programmable delay unit. Programmable delay units can be connected in series or in parallel to increase the number of possible delays and/or to specify timing parameters of portions of the memory unit in absolute or relative terms. Programmable delay units can be used to vary the timing characteristics of the memory unit and to control the voltage split used to read data.