학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2016. 2. 남상욱.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.Chapter 1. Introduction 1
1.1. WBAN (Wireless Body Area Network) 1
1.2. Challenges in Designing Transceiver for Medical Implant Application 7
Chapter 2. Propagation Loss in Human Body 10
2.1. Introduction 10
2.2. Far field approximation in human-body 13
2.3. Calculation of propagation loss in human-body 15
2.3.1. Frisss formula 15
2.3.2. Efficiency of transmitting antenna in human-body 17
2.4. Calculation of propagation loss in human-body and conclusion 19
Chapter 3. A Design of Transceiver for Capsule Endoscopy Application 21
3.1. Introduction 21
3.2. System Link Budget Calculation 24
3.3. Implementation 26
3.3.1. Transmitter with class B amplifier 26
3.3.2. Super-heterodyne receiver with AGC 28
3.3.3. Measurement results 30
3.4. Image recovery experiment 35
3.4.1. Integration of capsule endoscopy 35
3.4.2. Image recovery in the liquid human phantom 38
3.4.3. Image recovery in a pigs stomach and large intestine 40
3.5. Conclusion 41
Chapter 4. Super-Regenerative Receiver with Digitally Self-Quenching Loop 42
4.1. Introduction 42
4.1.1. Selection of receivers architecture for implantable medical device 44
4.1.2. Previous study of super-regenerative receiver 50
4.2. Main idea of proposed super-regenerative receiver 51
4.3. Description of proposed receiver 53
4.3.1. Digital self-quenching loop 55
4.3.2. Low noise amplifier and super-regenerative oscillator 57
4.3.3. Active RC filter for low power consumption 59
4.4. Experimental results 63
4.5. Summary and conclusion 69
Chapter 5. A Transmitter with Current-Reused and Current-Combining PA 71
5.1. Introduction 71
5.1.1. Previous study of OOK transmitter 72
5.2. Main idea of proposed transmitter 73
5.3. Description of proposed transmitter 79
5.3.1. Current-combining and current-reused PA 79
5.3.2. Ring oscillator with driving buffer 83
5.4. Experimental Results 85
5.5. Summary and conclusion 93
Chapter 6. Conclusion 95
Chapter 7. Appendix 97
7.1. Output spectrum of OOK signal 97
7.2. Theoretical BER of OOK comunication 99
Bibliography 101
초 록 109Docto
