An implantable stimulation system for generating and delivering therapy to a patient, said stimulation system comprising a stimulator 138 for generating the therapy； a conductive stimulation lead 134 having a proximal end electrically coupled to said stimulator 138； a stimulation electrode 132 positioned proximate a distal end of said stimulation lead； and characterised by an impedance matching circuit 154 electrically coupled to said lead 134 configured to substantially match the impedance of said stimulator 138 to the characteristic impedance of said lead 134, said impedance matching circuit 154 comprising a resistive circuit comprising a resistor 144 for producing a frequency independent component； a comparator 162 having a first input, a second input, and an output, said first input coupled to said resistor 144 and said output of said comparator 162 for generating a signal related to the voltage across said resistor 144； a processor 164 having a first input coupled to the output of said comparator 162, a first output coupled to the second input of said comparator 162, and having a second output； and a variable impedance circuit 166 coupled to said resistor 144 and to the second output of said processor 164, said processor for adjusting the impedance of said variable impedance circuit 166 in response to the output of said comparator 162.
