An intermediate coupler is used to improve inductive coupling between an external charger and an implantable medical device having a battery requiring charging. The intermediate coupler comprises a coil (inductor) coupled to a capacitor, whose values are chosen to resonate at the frequency of the magnetic field emitted by the external charger. The intermediate coupler preferably contains no power source such as a battery, and can operate passively. When the intermediate coupler receives the magnetic field from the external charger, a current is induced in its coil, and the intermediate coupler generates its own magnetic field which is captured by the implantable medical device and used to charge its battery.
