An 8-Channel 9-V-Compliant Crosstalk-Free Bipolar Biphasic Current-Controlled Neural Stimulator in a Standard CMOS Technology

An 8-channel bipolar biphasic current-controlled stimulation IC based on a low-voltage standard CMOS technology is presented in this work. The stimulation IC features the voltage compliance of as much as 9 V through transistor-stacking and achieves reliable operation regardless of the load impedances. The proposed design allows simultaneous multi-channel stimulation without inter-channel crosstalks. A serial peripheral interface (SPI) is employed to program the IC. Seven magnitude levels of the stimulation current from 10 μA to 70 μA can be generated with an inaccuracy of only 1.73%. The IC is fabricated in a 0.18-μm 1.8-V/3.3-V standard CMOS process with each stimulation channel of a compact size. A head-stage including the IC and electrodes along with a custom-designed software user-interface is demonstrated with measurement results.