A multi-chip modular wafer level package of a high voltage unit for an implantable cardiac defibrillator includes one or more high voltage (HV) component chips encapsulated with other components thereof in a polymer mold compound of a single reconstituted wafer, wherein all interconnect segments are preferably located on a single side of the wafer. To electrically couple a contact surface of each HV chip, located on a side of the chip opposite the interconnect side of the wafer, the reconstituted wafer may include conductive through polymer vias; alternately, either wire bonds or layers of conductive polymer are formed to couple the aforementioned contact surface to the corresponding interconnect, prior to encapsulation of the HV chips. In some cases one or more of the components encapsulated in the reconstituted wafer of the package are reconstituted chips.