A Neural Stimulator IC with Dynamic Voltage Scaling Supply and Energy Recycling for Cochlear Implant in Standard 180nm CMOS Process

This paper presents the design of a high-voltage multiplexer (HVMUX) based stimulator with dynamic voltage scaling supply (DVSS) and energy recycling operations for cochlear implant. The proposed device involves a 3-stage charge pump (CP) converting input voltage VDD to multiple output voltages of up to 4VDD, four stimulating channels with fully-integrated HVMUX plus high-voltage adapter (HVA) circuits and additional adaptive control feedback loops. The 3-stage CP generates 4VDD voltage of 12V under a load current of 1.5mA. In case of slow-charging scenario across electrode-tissue interface, the accumulated charge can be recycled in reverse biphasic phase through dynamic control to improve the overall system energy efficiency. The proposed stimulator is implemented using a 180nm standard CMOS process, occupying a total die area of 3.75 mm
²
where each channel only takes up 0.4 mm
²
.