Design of an Exponential Current Generator for Neural Stimulation

This paper proposes a new exponential current generation circuit design for neural stimulation. The use of exponential output current can improve the power efficiency. The proposed exponential current generator is designed based on the Taylor series approximation, which can produce the continuous-time exponential decaying current with improved dynamic range and accuracy. The circuit is designed based on 180 nm CMOS process in Cadence. Simulation results show the relative error is smaller than 1% when the pulse width is 700 μs. The maximum current decaying dynamic ratio of the stimulator is 11.96 dB, which is improved by 2.3 times compared with similar neural stimulators.