Design And Research On Integrated Circuit Used In Implantable Transcutaneous Energy Transmission

With the development of medical technology, there are more and more researches inimplantable medical products bringing the hope to the patient. In these fields, a hot topic istranscutaneous energy transfer, which helps to supply energy to medical device and avoid thedrawbacks of traditional wired energy transfer. This technology using electromagneticcoupling between the inductor coils to transmit energy, electromagnetic energy received bythe body coil must be converted and managed to the medical probe device implanted in thebody. At present, most of the studies are based on discrete devices to build energy recoveryand management systems, which have too large circuit size and power consumption,increasing the difficulty for implant. In this article by the National Natural Science Fund, ahighly integrated wireless power recovery system with multiple functions, which isimplemented with integrated circuits and achieve a smaller implant size, lower powerconsumption and improve transport efficiency and safety, is presented.First of all, this paper analyzes the energy recovery and management system link, and thepart which is implemented with integrated circuits, then a detailed statement on the workingprinciple of each module and circuit design is presented. Energy recovery module includes arectifier circuit, bandgap reference, low dropout linear regulator (LDO). In LDO design, thispaper proposes a dynamic pole-zero compensation mechanism and VCCS control methods toimprove the stability of the system, and a forword-transconductance path is given to improvethe power supply rejection ratio; Energy management module includes a feedback circuit,over-current and over-temperature protection circuit. The feedback regulation circuit involvesa triangular wave generator which can easily set the high and low voltage, using the principleof PWM DC error amplifier and the load capacitance modulation to achieve energy feedbackregulation. In contrast to the traditional scheme, this circuit is easily to implemented andreliable. All the modules have the design specifications and performance parameters, andsimulation results.Circuit and layout design of the module in the paper is implemented by the process ofGlobal Foundry0.18um CMOS. Post-layout simulation results show that Energy recoverymodule can recover the AC power to1.8V DC energy which has the load of60mA, and thequiescent current is less than200uA, the power supply rejection ratio is less than-90dB at DC,when the1MHz is less than-30dB, and LDO phase margin of LDO is greater than60degreeswhen the output change from no load to60mA. The feedback regulation protection circuitprotects the device under poor working conditions, which improves the safety of implantable medical devices.