of fig5 the center frequency of resonance is fc 2 u03c0 sqrt lc u2212 1 where l comprises the inductance of the coil l 17 the effect as with the driving circuit 200 of fig5 is that recovery current i e is shunted to the rechargeable battery 76 during high voltage portions of the resonance providing a very energy efficient solution although vl is clamped to vlmax which limits the magnetic field producible by the coil 17 such magnetic field reduction does not result from energy dissipation caused through the use of a discrete resistor and once again shunting the recovery current i e to the battery assists in dampening the resonance which allows for the transmission of higher data rates additionally and as before such active dampening also tends to widen the resonant response of the resonant circuit easing reception without the need for hardware trimming the various values for the components used in the improved driving circuit 200 u2032 of fig6 may be as follows for the medical implantable device system for which the circuit was originally developed n 1 u02dc 20 turns n 2 u02dc 4 turns l 34 u03bch c 0 047 u03bcf vbat 4 1v cbp 100 u03bcf however in a different application different component values could be chosen the disclosed driving circuits can be used with any switching type amplifier class c d e h etc and for both the transformer feedback configuration fig5 and the autotransformer fig6 configuration while disclosed in the context of a medical implantable device system for which the invention was originally contemplated it should be recognized that the improved driving circuitry disclosed herein is not so limited and can be used in.