Patent ID: 7844773

Claim:
A refresh method in a semiconductor memory device including a plurality of bank groups each having a plurality of banks, the method comprising: applying an all-refresh command to one of the plurality of bank groups; determining if the one of the plurality of bank groups includes a bank undergoing a refresh operation; and performing an all-refresh operation that is based on the determining in response to the applied all-refresh command, wherein performing the all-refresh operation includes, beginning the all-refresh operation with a bank group refresh of the one of the plurality of bank groups if the determining determines the one of the plurality of bank groups does not include the bank undergoing the refresh operation; and beginning the all-refresh operation with a bank group refresh of a bank group different from the one of the plurality of bank groups if the determining determines the one of the plurality of bank groups does include the bank undergoing the refresh operation, and the determining includes storing information of the bank group including the bank undergoing the refresh, and comparing the stored information with information of the one of the plurality of bank groups to which the all-refresh command is applied; and the performing begins the all-refresh operation with the bank group refresh of the one of the plurality of bank groups if the stored information does not match the information of the one of the plurality of bank groups to which the all-refresh command is applied, and begins the all-refresh command with the bank group refresh of a bank group different from the one of the plurality of bank groups if the stored information matches the information of the one of the plurality of bank groups to which the all-refresh command is applied.