Abstract: An apparatus includes: a ZQ connection configured to provide a reference resistance level for a ZQ calibration process that tunes one or more resistance levels associated with input/output signals at a corresponding one of a plurality of dies; one or more slave dies that are configured to implement the ZQ calibration process or a portion thereof; a master die configured to implement the ZQ calibration process or a portion thereof; and a calibration channel configured to communicate signals between the master die and the one or more of the slave dies for coordinating access to the ZQ connection across the connected dies in implementing the ZQ calibration process, wherein the plurality of dies includes the master die and the one or more slave dies.