Active-on-active microelectronic devices are described. For example, a first die is on a second die with a bottom surface of a first substrate facing a top surface of a second substrate, respectively, to provide a die stack. The first and second dies each have metal layers in ILD layers to provide a first stack structure and a second stack structure, respectively. The first stack structure is interconnected to an upper end of a TSV of the first die. A metal layer of the second stack structure near a bottom surface of the first substrate is interconnected to a lower end of the TSV. A power distribution network layer of the second stack structure is located between lower and upper layers of the metal layers thereof. A transistor located at least in part in the second substrate is interconnected to the power distribution network layer to receive supply voltage or ground.