Refresh initiated precharge technique for dynamic random access memory arrays using look-ahead refresh

摘要

A refresh initiated precharge technique using look-ahead refresh eliminates the need to close banks in a dynamic random access memory ("DRAM") array prior to executing a "refresh" command by taking advantage of the fact that the actual initiation of an internal "refresh" operation is delayed by at least one clock cycle from the execution of the external "refresh" command. The technique is effectuated through the issuance of a "refresh" command to cause all banks within the DRAM array to precharge. This precharge occurs prior to the n-cycle delay (where N=1 or more clock cycles) of the internal "refresh" operation. Consequently, it is then unnecessary to execute specific "precharge" commands to close all open banks prior to executing the "refresh" command which frees otherwise consumed instruction bus bandwidth and guarantees that all banks have been precharged (are idle; a required condition) prior to the initiation of on-chip refresh operations. In this manner, the requirement for precharging all banks is automatically satisfied and the associated controller design may be concomitantly simplified.