在此介紹一種利用E類功率放大器的無線能量傳輸(Wireless Power Transfer)傳送器。在可植入式生物醫學系統的特定應用中，負載條件變化還有線圈相對位置的變化顯著影響接收端的電壓、功率傳輸能力(Power Transfer Capability)和功率轉換效率(Power Transfer Efficiency)，以上都需很大的設計餘量。在提出的設計當中，我們採用阻抗壓縮網路(Impedance Compression Network)來壓抑阻抗的變化並穩定性能。另外，我們引入了佔空比(Duty Cycle)控制系統以進一步改進性能。
設計並實作在0.18 微米互補式金屬氧化物半導體製程，且操作頻率為13.56百萬茲，此無線能量傳輸系統包含了我們所提出的功率傳送器以及先前設計的功率接受器。在負載變化範圍從65到85歐姆條件下，量測結果顯示整流器的輸出電壓在線圈相對距離介於9.5毫米到32毫米之間(相對於耦合係數(k) 為0.038 到0.22)均可達到1.3 伏特以上，而輸出功率可達到26 毫瓦以上。系統最大輸出功率在耦合係數為0.2 時可達到48.8 毫瓦，在耦合係數為0.2 且伴隨著汲極效率為81% 時，系統最大輸出功率轉換效率為45.6% 。從量測中也得到可調式開關佔空比範圍在10% 到90% 之間。相較於傳統架構，我們所提出的設計達到目標輸出電壓和輸出功率同時實現了較廣的動態範圍。

A wireless power transfer (WPT) transmitter with class E power amplifier is presented in this work. In the target application of
implantable biomedical systems, variations of load condition as well as coil separation have significant impact on received voltage, power transfer capability (PTC), and power transfer efficiency (PTE), demanding for large design margin. In the proposed design, we adopted an impedance compression network (ICN) to compress the resulting impedance variation and, therefore, stabilize the performance. Duty-cycle control (DCC) system is introduced for further improvement.
Implemented in a 0.18 mm CMOS process, at 13.56 MHz, the WPT system includes the proposed transmitter and a previously designed power receiver. With load resistance varying from 65 to 85 W, measurement results show the rectifier’s output voltage of more than 1.3 V and power of more than 26 mW as the coil distance varies from 9.5 to 32 mm, which corresponds to a k range of 0.038 to 0.22. The maximum output power is 48.8 mW at k of 0.075, and the maximum PTE is 45.6% with PA drain efficiency of 81% at k of 0.2. Adjustable switching duty cycle can be obtained in the range of 10% to 90%, and further helps to improve the performance by up to 78.7%. Compared to conventional structures, the proposed design achieves wide dynamic range while meeting the target output voltage and power.

Abstract
Contents i
List of Tables iv
List of Figures v
1 Introduction 1
1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.3 Thesis Overview . . . . . . . . . . . . . . . . . . . . . . 5
2 Inductive-Based Wireless Power Transfer System . . . . . . 6
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2 General Structures of Inductive-based WPT system . . . . . . 8
2.2.1 Transmitter System . . . . . . . . . . . . . . . . . . . . 8
2.2.2 Coupling Coil . . . . . . . . . . . . . . . . . . . . . . 12
2.2.3 Receiver System . . . . . . . . . . . . . . . . . . . . . 15
2.3 Analysis of Inductive WPT Circuit . . . . . . . . . . . . . 17
2.3.1 Equivalent Circuit Model . . . . . . . . . . . . . . . . .17
2.3.2 Analysis of Power and Transfer Efficiency in WPT system 21
2.3.3 Basic Structures of Resonant Topology . . . . . . . . . . 23
2.4 Design Specifications . . . . . . . . . . . . . . . . . . . 31
3 Power Transmitter Design with Impedance Compression Network 34
3.1 Theorem of Class E Power Amplifier . . . . . . . . . . . . .34
3.1.1 Basic Structure and Operation . . . . . . . . . . . . . . 34
3.1.2 Analysis and Introduction . . . . . . . . . . . . . . . . 37
3.1.3 Derivation of Formula . . . . . . . . . . . . . . . . . . 40
3.2 Impedance Compression Network . . . . . . . . . . . . . . . 56
3.3 Control Circuit Implementation . . . . . . . . . . . . . . .66
4 Measurement Results 72
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . .72
4.2 Inductive Circuit Implementation . . . . . . . . . . . . . .73
4.2.1 Coupling Coil with Resonant Capacitor . . . . . . . . . . 73
4.2.2 Measurement of Coupling Coefficient . . . . . . . . . . . 78
4.3 Measurement of WPT System . . . . . . . . . . . . . . . . . 80
4.3.1 PCB . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
4.3.2 Measurement Setup . . . . . . . . . . . . . . . . . . . . 82
4.3.3 Measurement of WPT System . . . . . . . . . . . . . . . . 83
5 Conclusion 93
Bibliography 94

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