本篇論文展示了用於微波加熱系統的915 MHz 700 W連續波固態射頻放大器設計與600 W模組製作流程。此射頻放大器採用了推挽式操作以獲得較純的頻譜，以利於未來研究微波加熱效果與頻率的關係。推挽式操作係利用一新提出的縮小版馬相巴倫達成。此巴倫由一個橢圓狀的上下耦合線構成，材料損耗僅1.5 %並且相較同軸巴倫更利於批量生產。我們先利用HFSS做放大器初步阻抗匹配電路設計接著再在高功率實驗中手動調整匹配電路。根據實驗經驗，放大器的增益主要與輸入匹配電路有關，而汲極效率主要與輸出匹配電路有關。最終設計出的放大器使用NXP推出的MRF13750H電晶體，採用class AB操作(工作點150 mA)，在915 MHz達到700瓦連續波輸出、64.2 %汲極效率與21.5 dB增益。我們也新提出了一個高方向性的耦合器做功率監測，此耦合器由多段非對稱的微帶耦合線構成，在915 MHz達到39.6 dB方向性。我們整合了設計出的放大器、輸入與輸出耦合器、環行器、溫度與電流感測器、與功率偵測器組成一個放大器模組，提供600 W左右的微波輸出。我們亦製作了一個30 W前級放大器並整合了Arduino無段功率控制系統與TFT監控面板。3個600 W功率放大器模組未來會做功率合成得到最大1.8 kW功率輸出，並將應用在大型碳纖維預氧化系統甚至大型微波烘豆系統中。

We demonstrate the development of the 700W (CW) solid-state RF power amplifier and 600 W (CW) power amplifier module for use in the lab-scaled 915 MHz heating system. The amplifier adopts push-pull operation for better spectrum purity – an important issue in investigating the influence of microwave frequency on material processing. The push-pull operation is achieved by a newly-proposed miniaturized Marchand balun. The balun consists of broadside-coupled lines with elliptical structure, achieving a 1.5% material loss comparable to other types of baluns while easier for batch production. The power amplifier matching circuit is initially designed in HFSS and manually tuned in high power experiment. According to the experience, the amplifier gain/efficiency is mainly influence by the input/output matching circuit. The finalized amplifier uses NXP’s MRF13750H transistor, adopting class AB operation (IDQ = 150 mA) and achieving 700 W (CW) output power, 64.2 % drain efficiency and 21.5 dB gain. We also proposed a novel high-directivity directional coupler for power monitoring. The coupler is a multi-section microstrip coupler specially designed for high-power purpose. We integrate the amplifier with the input/output directional couplers, the isolator, the temperature and current monitor, and the power detectors into a 600 W amplifier module. We fabricate a 30 W pre amplifier as the driver amplifier, integrating it with a stepless power control system realized by Arduino micro-controller and a TFT monitor that displays up to 3 module information. Three of the developed modules will be combined to yield 1.8 kW max output power, and will be used in a 915 MHz large-area PAN fiber processing system.

誌謝-----------------------------------------------------------------i
中文摘要------------------------------------------------------------ii
ABSTRACT-----------------------------------------------------------iii
CONTENTS------------------------------------------------------------iv
LIST OF FIGURES---------------------------------------------------viii
LIST OF TABLES------------------------------------------------------xi
Chapter 1 簡介------------------------------------------------------1
1.1 研究動機---------------------------------------------------------1
1.2 功率放大器衡量指標------------------------------------------------1
1.2.1 穩定性因子-----------------------------------------------------1
1.2.2 增益-----------------------------------------------------------2
1.2.3 效率-----------------------------------------------------------3
1.2.4 線性度與諧波----------------------------------------------------3
1.2.5 雜訊(spurs)----------------------------------------------------5
1.3 功率放大器基本工作原理---------------------------------------------5
1.3.1 負載線(load line)----------------------------------------------5
1.3.2 導通角(conduction angle)---------------------------------------6
1.3.3 各class效率比較------------------------------------------------8
1.3.4 提高效率方法----------------------------------------------------9
1.4 常見功率放大器架構-----------------------------------------------11
1.4.1 平衡式放大器---------------------------------------------------11
1.4.2 推挽式放大器---------------------------------------------------11
Chapter 2 915 MHz推挽功率放大器設計與模組製作------------------------13
2.1 915 MHz上下耦合(Broadside-Coupled)平面式巴倫[1-6]----------------13
2.1.1 平面式巴倫設計概念---------------------------------------------13
2.1.2 平面式巴倫模擬-------------------------------------------------15
2.2 915 MHz推挽高功率放大器電路設計[7-16]-----------------------------18
2.2.1 功率放大器架構-------------------------------------------------18
2.2.2 阻抗匹配電路與偏壓電路設計--------------------------------------19
2.2.3 電路佈局圖----------------------------------------------------23
2.2.4 功率放大器零件表-----------------------------------------------24
2.3 915 MHz高功率放大器製作與測試-------------------------------------25
2.3.1 功率放大器製作-------------------------------------------------25
2.3.2 功率放大器測試平台---------------------------------------------27
2.3.3 功率放大器測試流程---------------------------------------------28
2.3.4 功率放大器量測結果---------------------------------------------29
2.4 915 MHz高方向性微帶耦合器設計與製作[17-20]------------------------31
2.4.1 方向耦合器設計-------------------------------------------------31
2.4.2 方向耦合器量測結果---------------------------------------------34
2.5 功率放大器模組整合-----------------------------------------------35
2.5.1 放大器模組主要元件介紹------------------------------------------35
2.5.2 600瓦放大器模組整合與高功率測試---------------------------------36
2.5.3 放大器資訊監控-------------------------------------------------37
2.6 功率放大器模組零件採買網址----------------------------------------38
Chapter 3 30 W 可調功率訊號產生模組---------------------------------40
3.1 模組設計與製作---------------------------------------------------40
3.1.1 模組架構------------------------------------------------------40
3.1.2 模組主要元件介紹-----------------------------------------------41
3.1.3 模組整合------------------------------------------------------41
3.1.4 模組零件採買清單-----------------------------------------------42
3.2 模組控制--------------------------------------------------------43
3.2.1 SPI通訊介紹---------------------------------------------------43
3.2.2 ADF4351控制---------------------------------------------------43
3.2.3 DAC8552控制---------------------------------------------------43
3.2.4 ST7735控制----------------------------------------------------43
3.2.5 自製訊號產生器通訊方法-----------------------------------------44
3.3 放大器模組與訊號產生模組整合測試----------------------------------44
Chapter 4 功率放大器模組未來應用領域---------------------------------45
4.1 PAN絲處理系統---------------------------------------------------45
4.2 大型烘豆系統-----------------------------------------------------46
Chapter 5 結論-----------------------------------------------------47
參考文獻------------------------------------------------------------48
附錄一、功率放大器實驗記錄表格----------------------------------------50
附錄二、功率放大器模組機械加工圖--------------------------------------51
附錄三、功率放大器模組NANO程式----------------------------------------77
附錄四、訊號產生模組NANO程式------------------------------------------81
附錄五、訊號產生模組MEGA2560程式--------------------------------------86

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