Design and Implement of Wireless Power Telemetry Circuits for Implantable Biomedical Micro-System

近年來微型電子系統在生醫領域方面有蓬勃發展的趨勢，藉由可植入系統的微小化與電氣化，病人的不適症與疼痛感可大幅的減低，診療的正確性也可大幅的提升。這些系統通常由兩個部份所組成：內部可植入式詢答器與外部讀取元件，藉由無線傳輸的方式彼此傳遞資訊與能量。能量從外部元件傳遞到內部植入系統，提供內部系統的感測與運算，再將資訊從內部系統透過無線通訊的方式傳輸到外部元件，而外部元件也可將指令透過無線通訊傳輸到內部系統，因此，能量是單向的，而資訊是雙向的，很多生醫通訊的方式都是透過這樣的方式達成。在應用當中，能量成為了最關鍵性的問題，因為它限制了應用的性能與範圍，為了要確保這些植入系統的性能，在本篇論文中，我們將討論一些可以提升能量效率的方法。 這篇論文中包含了四顆關於無線功率傳輸系統之晶片的設計與實作：由於電感耦合連結的效率主要是由整流效率與傳輸的共振頻率所決定，所以一開始我們提出了一個具備頻率校正功能的無線功率傳輸系統與一個可應用在高電流的全波式整流器。然而，整流後的電壓需要經由穩壓處理之後才可以提供給後續電路作為一個穩定的直流電源，但是整流後的電壓再經過穩壓後，效率往往會浪費一大截，因此我們更進一步設計了一個結合整流與穩壓功能的整流穩壓器來減少電路內部能量浪費。最後，我們設計了一個利用動態零點補償的低壓降線性穩壓器，利用動態的零點去追蹤輸出電流的方式，使得用來提升穩定度之輸出電容與其寄生電阻的可應用範圍增加，如此一來，更可適用在情況多變的無線功率傳輸系統而不失其穩定的特性。Microelectronic systems are currently hot topics in biomedical field to miniaturize implantable devices, reduce the pain of the patients and increase accuracy of the diagnosis. These systems are usually composed of implanted transponder and external components, which connected wirelessly across the skin. Power is transferred form external unit to implant, while data is transmitted between each other. These contribute lots of biomedical communication system. Up to now, power of these devices has been critical issues due to their limitations of performance. In order to confirm the performance of these devices, several methods to enhance power efficiency are discussed in this thesis. This thesis contains four designs and implementations of the blocks of wireless power telemetry system. First, we proposed a wireless power transmission system with frequency calibration together with a high-current full-wave rectifier circuit since the efficiency of an inductive power link is mainly determined by these two factors - rectification efficiency and resonant frequency. Then, an integrated rectified regulator using active diodes is introduced to further enhance the regulation efficiency. By combining active diodes with a resistive feedback loop, sinusoid RF signals are directly converted to a regulated dc output to supply the following circuits. Finally, a CMOS low dropout linear regulator using dynamic zero compensation is proposed. By introducing a dynamic zero to track the output load current, the tolerant range of the output capacitor and equivalent series resistance (ESR) is widened, which is proper for a wireless power transmission system.Abstract ……………………………………………………………….… I Contents ……………………………………………………………….… V List of Figures ……………………………………………………………….… IX List of Tables ……………………………………………………………….… XVII 1 Introduction……………………………………………………………… 1 1.1 Background………………………………………………………………... 1 1.2 Motivation …….…………………………………………………………... 3 1.3 Thesis Organization ………………………………………………………. 4 2 Basics of the Wireless Power Telemetry System ………………………… 7 2.1 Architecture of wireless power telemetry system ………………………… 7 2.1.1 Rectifiers…………………………………………………….............. 9 2.1.2 Regulators and Limiters ……………………………………………… 11 2.1.3 Clock Extractors …………………………………………………….. 13 2.1.4 Class-E amplifier ……………………………………………………. 14 2.1.5 Data Modulations ……………………………………………………. 15 2.2 Analysis of Litz wires …………………………………………….…..…. 17 2.3 Analysis of low dropout linear regulator ………………………………... 20 2.3.1 Dropout Voltage ……………………………………………………... 21 2.3.2 Quiescent Current ……………………………………………………. 22 2.3.3 Power efficiency …………………………………………………….. 23 2.3.4 Line Regulation ……………………………………………………… 24 2.3.5 Load Regulation ……………………………………………………... 25 2.3.6 Power Supply Rejection Ratio ………………………………………... 26 2.3.7 Transient Response of LDO Linear Regulator ………………………… 27 2.3.8 Stability of LDO Linear Regulator …………………………………... 30 3 A Wireless Power Transmission System with Frequency Calibration ……………………………………………………………… 35 3.1 Motivation ………………………………………………………………. 35 3.2 An Active High-Current Full-Wave Rectifier ………………………….. 37 3.2.1 Conventional Full-Wave Rectifier ………………………………….... 37 3.2.2 Proposed Active Full-Wave Rectifier ……………………………….… 38 3.2.3 Simulation Results and Chip Layout ………………………………….. 40 3.2.4 Experimental Results ………………………………………………… 44 3.3 A Wireless Power Transmission System with Frequency Calibration …... 50 3.3.1 Architecture …………………………………………………………. 50 3.3.2 Circuit Design and Simulation Results ………………………………... 53 3.3.3 Chip Layout …………………………………………………………. 58 3.3.4 Experimental Results ………………………………………………… 60 4 An Integrated Rectified Regulator Using Active Diodes………………. 69 4.1 Motivation ………….……………………………………………………. 69 4.2 Architecture ……………………………………………………………… 70 4.3 Circuit Design and Simulation Results ………………………………….. 73 4.4 Layout …………………………………………………………………… 77 4.5 Experimental Results ……………………………………………………. 77 4.5.1 Test Setup …………………………………………………………… 78 4.5.2 Measurement Results ………………………………………………… 79 4.5.3 Performance Summary ………………………………………………. 86 5 A Low Dropout Linear regulator Using Dynamic Zero Compensation 89 5.1 Motivation ……………………………………………………………….. 89 5.2 Architecture ……………………………………………………………… 90 5.3 Circuit Design and Simulation Results ………………………………….. 92 5.3.1 Circuit Design ……………………………………………………….. 92 5.3.2 Frequency Response ………………………………………………… 93 5.3.3 Simulation Results …………………………………………………… 96 5.4 Layout …………………………………………………………………… 99 5.5 Experimental Results …………………………………………………… 99 5.5.1 Test Setup …………………………………………………………… 99 5.5.2 Measurement Results ……………………………………………… 100 5.5.3 Performance Summary ……………………………………………… 102 Chapter 6 Conclusions……………………………………………………. 105 Bibliography………………………………………………………………….. 107 Publication List……………………………………………………………… 11