Biography
Enrollment Date: 2011
Graduation Date：2014
Degree：M.S.
Defense Date：2014.05.29
Advisors：Songping Mai
Department：Graduate School at Shenzhen，Tsinghua University
Title of Dissertation/Thesis：Wireless Front-End With Power Management for Implantable Neurostimulators
Abstract:
With the development of human medical technology, implantable neurostimulators are more and more used in health recovery. Implantable neurostimulators stimulate targeted nerve with current or voltage of certain amplitude, frequency and time duration, in order to recover the function of the brain, nerve or muscle. Implantable neurostimulators are implanted in human body, which need to communicate with external circuits to receive energy and control information, and also inform the external circuits of the operation state of the implanted circuits. Therefore, a high-efficiency, low-power wireless power and data frontend is crucial to the implantable applications. In addition, in order to ensure the implantable neurostimulator operates normally when there is no wireless power, rechargeable batteries are needed in implantable applications to provide stable power supply and store received energy. To address the above requirements, this paper has done the following research in csmc 1μm high-voltage process: A full-wave rectifier with two offset comparators is proposed. The offset comparators control the switching states of the rectifying MOS transistors precisely, preventing the reverse current, which improves the efficiency of the rectifier. The power conversion efficiency achieves as high as 94.1% for input power of 254mW.A simple back telemetry is implemented with LSK modulation, of which the power consumption is very low and the structure is easy to use. Simulation result shows that the data rate is above 30Kbps, which meets the low-data-rate implantable applications.A pre-charge, current-limiting, voltage-limiting scheme Li-Ion charger is designed with linear charging structure. It provides temperature protection and over-charge protection, which achieves power efficiency as high as 88.6%.A classic low-dropout regulator is designed for 3V low-voltage power supply, with output current from 0 to 5mA. And a charge pump is designed for 12V high-voltage power supply with output current from 0 to 12mA, of which the power efficiency is up to 75.1%.