의료용 인체 삽입물을 위한 무선 저전력 송수신기에 관한 연구

Abstract

This thesis presents the wireless transceiver for medical implant application. The high propagation loss in human body which has high relative permittivity and conductive makes the implantable device be required for high sensitivity. Moreover, the device should have low power consumption to use for wireless implant medical application due to a restricted battery life. Also, this problem should be solved for on-body device considering integration with mobile device in the future. Simultaneously, the specific medical application such as epiretinal prosthesis, multi-channel electroencephalogram sensor demand high-data rate. Therefore, it is a main challenge that enhancing the devices power consumption and data-rate for implantable medical application. In order to enhance the performance of the device, several techniques are proposed in implantable human body transceivers. Firstly, the propagation loss in human-body is calculated for determine the frequency for medical implant application. The frequency bands allocated by FCC or MICS are too narrow and high lossy bands in human-body. For this reason, the optimum frequency for Implantable medical device is found by using Frisss formula and the link budget is calculated for capsule endoscopy system. The optimum frequency is verified through image recovery experiment in liquid human phantom and pig by using designed capsule endoscopy system. Secondly, the Super-Regenerative Receiver (SRR) with Digital Self-Quenching Loop (DSQL) is proposed for low power consumption. The proposed DSQL replaces the envelope detector used in a conventional SRR and minimizes power consumption by generating a self-quench signal digitally for a super-regenerative oscillator. The measurement results are given to show the performance of the proposed receiver. Thirdly, the RF Current Reused and Current Combining (CRCC) Power Amplifier (PA) is proposed for low power and high-speed transmitter. Normally, the PA having low output power has a feasibility issue that an optimum impedance of PA is too high to match with antenna impedance. For this reason, obtaining the maximum efficiency of PA is difficult for conventional structure. Moreover, conventional PAs output bandwidth is to be narrow due to high impedance transform ratio between PAs output and antennas input impedances. The CRCC structure solves this issue by decreasing the impedance transform ratio. The transmitter with CRCC PA is designed and verified through the measurement.