An Energy-Efficient, Scalable Neural Stimulation IC with Adaptive Dynamic Voltage Switching for Cochlear Implant System

We present an energy-efficient, scalable neural stim-ulation IC with adaptive dynamic voltage switching, which can be applied to cochlear implant (CI) systems. The stimulation IC generates three different voltage outputs by operating a single-inductor multiple-output (SIMO) boost converter, while an adaptive dynamic voltage switching (ADVS) block selects an appropriate supply voltage for each stimulation channel among those SIMO outputs. The SIMO boost converter is designed to operate over a wide range of its input, which is the rectifier output of the wirelessly powered CI system. The ADVS control as well as the stimulation amplitude control are performed remotely by an external sound processor (SP) of the CI system in real time. For the ADVS operation, the compliance voltage of each stimulation channel is monitored to be used as an input signal for switching to the appropriate supply voltage for the corresponding stimulation channel. The dynamic voltage switching operation is carried out in sub-us, The stimulation IC with ADVS is implemented using a 180-nm BCD process, and its operation and performance are verified through post-layout simulations. When applying a real audio input using decoded data from a prototype SP, the proposed stimulation IC with ADVS demonstrates 36.6% energy saving compared to the conventional stimulation IC.