Design Of Power Management System Based On Implantable Wireless Charging Device

The development of integrated circuits has greatly advanced the development of medical implantable devices,which can be miniaturized to replace medical treatment.This paper studies the practical application of implantable medical devices based on wireless charging and designs a power management chip system for implantable neural stimulators based on wireless charging.Firstly,the neural stimulator system is planned and studied,and an active implantable neural stimulator system is designed.The system is powered by a lithiumion battery that can be recharged wirelessly.A Buck dc-dc converter controlled by voltage PWM was designed to obtain a stable supply voltage.According to the safety characteristics of lithium battery,the relevant over-voltage/under-voltage charging protection circuit is also designed.The output of the nerve stimulator is a biphasic physiological electrical stimulation module,which is a DAC circuit structure.Therefore,a negative pressure charge pump is designed to provide negative pressure power supply for the stimulator.The input voltage range of the converter is 3-4v,the output voltage is stable 2V,the maximum load current is 100 m A,and the conversion efficiency is 85.4%.An 2MHz oscillator is used inside the circuit,and the external device is simple in structure and small in size.The negative voltage charge pump module can stabilize the output-2v voltage signal,the maximum load current is 5m A,the use of cross coupling circuit,plug-in only needs two capacitors to achieve negative voltage generation,conversion efficiency of 76%.According to the design of the above power management module,this paper USES Sil Terra0.18 m CMOS technology to simulate the system and each sub-module in Cadence software and draw the layout.This power management module can provide a stable ±2V voltage for the biphasic nerve stimulator,which meets the requirements of the designed nerve stimulation power management parameters.