US Patent 9396766 Semiconductor device having memory chip stacks with TSV

A semiconductor memory device may include a plurality of memory chips stacked upon one another, and electrically coupled to one another through a plurality of first TSVs. The semiconductor memory device may include a plurality of second memory chips stacked separately from the first memory chips, and the plurality of second memory chips electrically coupled to one another through a plurality of second TSVs. The semiconductor memory device may include a plurality of external connection electrodes coupled to both to the first memory chips and the second memory chips. Wherein one of the first and second memory chips may be accessed in response to chip select signals inputted through the external connection electrodes.