Sabit akım stimülatörler için uyarlanabilir bir dönüştürücü

Functional electrical stimulation (FES) has been used to remedy neurological or physiological ailments for many years. Several methods for functional electrical stimulation exist, among which constant current stimulation is adopted by many devices thanks to its safety and charge control. One of the most successful among these devices is the cochlear implant. More than 120.000 people use them to improve the quality of their lives. In the last decade or so, the amount of research done to fully implant these cochlear implants has increased dramatically. To comply with the requirements of such a fully implanted device, rigorous specifications are necessary. One of the most important among these specifications is related to power consumption. Due to weight and volume restrictions the device must operate with ultra-low power. This, however, is quite difficult due to the necessity of high voltage compliance that is required for constant current stimulation. The high voltage must be generated with a converter circuit, which further degrades the efficiency of the system. To alleviate these issues an adaptive converter is designed in this thesis. The system tracks the voltages of an 8- channel stimulation electrode array. Accordingly, with the utilization of a 3-stage charge pump, the necessary supply voltage for the stimulator ranging from 1.8 V to 5.5 V is generated. This way up to 35% power dissipation reduction is observed within the neural stimulator compared to when the converter is operating in its constant 5.5 V configuration, resulting in a much more efficient overall system.