Design of High Output Impedance, Large Voltage Compliance Output Stage of Implantable Hypoglossal Nerve Stimulator (HGNS) for OSA Treatment

Abstract

Obstructive Sleep Apnea (OSA) is a potentially common sleep disorder manifested in upper airways' collapse, either partially or completely. If diagnosed late and untreated, it may result in serious complications. The standard golden method, useful for treating OSA, remains the full night Continuous Positive Airway Pressure (CPAP). Yet, due to the ensuing discomfort it incurs on patients, researchers have been motivated to investigate other efficient alternatives, whereby, OSA can be effectively treated. More recently, an increasingly popular OSA treatment solution has been developed that consists in activating the protrusion muscles of the tongue by stimulating the Hypoglossal Nerve (HGN). After discussing the classification topologies of some neural stimulator output design stages, we consider putting forward the design of output stage of Hypoglossal Nerve Stimulator (HGNS), in compliance with the HGN requirements. The proposed HGNS is simulated in cadence software using the 0.35µm CMOS technology and Matlab software. It proved to enable the delivery of a maximum stimulation current of 1mA through 1kΩ resistive load under 3.3V voltage supply. The output stage managed to achieve large voltage compliance of 94% of the voltage supply and high output impedance of 275MΩ at full scale stimulus current. The total power consumption is about 705.87µW.