Disclosed herein, among other things, are systems and methods for improved circuit design for hearing assistance devices. One aspect of the present subject matter includes a hearing assistance device configured to compensate for hearing losses of a user. The hearing assistance device includes a substrate and an interposer embedded into the substrate to form a system in package module. According to various embodiments, the interposer includes one or more integrated circuits (ICs) on the interposer, the one or more ICs configured to provide electronics for the hearing assistance device.