Design of Low Noise Voltage-Controlled Oscillators for WiMAX

[[abstract]]本論文係提出一運用於全球微波存取互通介面(Worldwide interoperability for Microwave Access, WiMAX)系統之低雜訊電壓控制振盪器(Voltage-Controlled Oscillator, VCO)設計。一般WiMAX頻段是座落在3.4GHz~3.6GHz，因此我們採用LC諧振振盪器( LC-tank Oscillator )型式來設計3.4GHz之低雜訊電壓控制振盪電路。理論部分則使用正回授、負電阻與反射係數型式之觀點分析，並藉由分析壓變電容二極體( Varactor )之特性，成功推導出輸出頻率與電路設計參數之關係。此外，我們也結合Agilent ADS(Advances Design System)模擬軟體來進行電路設計以及模擬。實作電路方面電晶體我們則是採用Agilent 公司的ATF-55143 Low Enhancement Mode MOSFET，壓變電容二極體是採用TOSHIBA公司的JDV2S02E之元件。最後模擬與實作之量測結果進行交叉分析比較，結果顯示我們所設計之電壓控制振盪器性能表現相當優異，3.4 GHz低雜訊電壓控制振盪電路輸出功率為-4.65dBm，輸出訊號在頻率位移100 kHz時相位雜訊可低於-104.22dBc/Hz，其操作頻率可涵蓋3.415~3.55 GHz。 由於數位電視的需求日益增加，技術也越來越成熟，因此寬頻調諧電路在RF設計上也相對變得重要。本論文因此也設計一應用於數位電視系統(48-682 MHz)之寬頻電壓控制振盪器，以雙次轉頻的架構中的第一中頻本地振盪之標準，其頻率範圍需在815 MHz以上。本論文使用平衡式電壓控制振盪器( Balanced VCO)線路架構來完成，稱之為單組式寬頻電壓控制振盪器。實作方面電晶體我們採用NEC公司的2SC5007，壓變電容二極體是採用Philips公司的BB135之元件。最後量測頻率為1.226~2.203 GHz，相位雜訊為-106.34 dBc/Hz@100kHz。[[abstract]]The thesis proposes a design of low noise Voltage-Controlled Oscillator (VCO) for Worldwide interoperability for Microwave Access, WiMAX Applications. Generally speaking, WiMAX frequency band is located in the 3.4GHz~3.6GHz, therefore, we design a 3.4 GHz low noise voltage-controlled oscillator by using the model of LC-tank Oscillator. Theoretically speaking, we analyze the feedback model, negative resistance model and reflection coefficient model respectively. And by analyzing the characteristics of varactor diode, we succeed in inferential reasoning the relationship between the output frequency and circuit of design parameter. In addition, we have also combined the simulation of Agilent ADS (Advanced Design System) software proceed with the circuit and simulation. As for the actual transistor, we used ATF-55143 Low Enhancement Mode MOSFET of Agilent. As for the varactor, we used JDV2S02E of TOSHIBA. The measurement of the final simulation and the actual operation is as a result to carry on crossing an analysis comparison, and the result shows that the VCO which we design works pretty well. The 3.4 GHz VCO has an output range of 3.415 to 3.55 GHz with a -4.65 dBm output power. The phase noise is as good as -104.22 dBc/Hz at 100 kHz offset from carrier frequency. Due to the increasingly need of digital TV, and the better technics, the design of the broadband tuning circuits also becomes important in RF designing. Consequently, in this thesis, we also design a broadband VCO of being used for the digital TV system (48-682 MHz) with the standard of the first IF that in the structure of the dual-conversion, and the range of the frequency scope must be above 815 MHz. The thesis is accomplished by using Balanced VCO which is implemented in a single module. Actually, we used 2SC5007 transistor of NEC and BB135 varactor diode of Philips. Final, it operates between 1.226 to 2.203 GHz with phase noise is -106.34 dBc/Hz at 100 kHz offset from carrier frequency