Abstract: The invention relates to an implantable pulse generator (100), IPG, for stimulation of a neurological cellular mass comprising a casing (2) that at least partially encloses the pulse generating module (PGM) (4) and that is transparent to radio-frequency electromagnetic fields, or wherein the pulse generating module (4) includes a controller circuit (18) provided as two or more circuit boards (20, 22), co-operatively connected, one such circuit board being an interface circuit board, where at least one component of the controller circuit (8) is located on the interface circuit board (20), and feed through wires for connector block (6) are connected thereto (20), and one of the opposing surfaces of the interface circuit board (20) is aligned over apertures (48, 50, 52) in the PGM housing for the feed through wires.