Structure and method for coupling signals to and/or from stacked semiconductor dies

Abstract

Signals are coupled to and from stacked semiconductor dies through first and second sets of external terminals. The external terminals in the second set are connected to respective conductive paths extending through each of the dies. Signals are coupled to and from the first die through the first set of external terminals. Signals are also coupled to and from the second die through the conductive paths in the first die and the second set of external terminals. The external terminals in first and second sets of each of a plurality of pairs are connected to an electrical circuit through respective multiplexers. The multiplexers in each of the dies are controlled by respective control circuits that sense whether a die in the first set is active. The multiplexers connect the external terminals in either the first set or the second set depending on whether the bonding pad in the first set is active.

What is claimed is: 
     
         1 . A semiconductor die, comprising:
 an electrical circuit;   a plurality of conductive paths extending at least partially through the die;   a first set of external terminals;   a second set of terminals, each of the terminals of the second set being paired with a respective one of the terminals of the first set, each of the terminals of the second set being coupled to a respective one of the conductive paths;   a plurality of multiplexers, wherein each of the multiplexers is coupled to a respective pair of terminals from the first and second sets, each of the multiplexers including a control terminal and respective input terminals coupled to respective ones of the external terminals of the first and second sets, each of the multiplexers being operable to couple either the respective external terminal of the first set or the respective external terminal of the second set to the electrical circuit; and   a control circuit having an input coupled to one of the external terminals of the first set, the control circuit being operable to determine whether the external terminal to which it is coupled is active, and, at least partially in response thereto, to apply a signal to the control terminals of the multiplexers that cause the multiplexers to couple the external terminals of the first set or the external terminals of the second set to the electrical circuit.