In one embodiment, an implantable pulse generator (IPG) for providing a neurostimulation therapy, comprises: pulse generation circuitry and pulse delivery circuitry for controlling generation and delivery of electrical pulses to a patient using one or more electrodes of a stimulation lead； measurement circuitry for determining characteristics of one or more electrodes selected for delivery of electrical pulses； and a processor for controlling the IPG according to executable code； wherein the IPG is adapted to calculate values for an impedance model of the one or more selected electrodes using the determined plurality of voltage measurements and to adjust current levels for the exponentially decreasing current pattern based on the calculated values for the impedance mode.
