Abstract: An implantable device, including a first electrically non-conductive substrate with a plurality of electrically conductive vias. The device also includes a flip-chip multiplexer circuit attached to the electrically non-conductive substrate using conductive bumps, the circuit being electrically connected to at a subset of the plurality of electrically conductive vias. Another a flip-chip driver circuit is attached to the flip-chip multiplexer circuit using conductive bumps while a second electrically non-conductive substrate attached to the flip-chip driver circuit using conductive bumps. Discrete passives are attached to the second electrically non-conductive substrate and a cover is bonded to the first electrically non-conductive substrate. The cover, the first electrically non-conductive substrate and the electrically conductive vias form a hermetic package.