A Reconfigurable 13.56MHz Wireless Powered CMOS Integrated Nerve Stimulator

This paper presents a nerve stimulation system implementation that contains full-wave rectifier-based energy harvester switching at 13.56MHz to generate stimulation current for accelerating the regeneration time of recovering damaged nerve. Reconfigurable eight-bit driver cells provide the selective option of controlling the stimulation current from as low as $4 \mu \mathrm{A}$ up to 0.92mA. The design is implemented in a standard 180nm CMOS process with a core area of 0.22mm
²
excluding a 3.6nF on-chip integrated capacitor which occupies 0.34mm
²
of the chip area. The fabricated chip is measured and characterized with coupled AC input amplitude of 2.2V and a driver load of $1 \mathrm{k} \Omega$. Furthermore, the measurement results verify the rectified DC output of 2V which implies a conversion ratio of 0.91.