窄頻2.4GHz無線區域網路與寬頻2-4GHz混成積體頻率合成器

Abstract

本篇論文提出S頻帶窄頻(2.4-2.484 GHz)及寬頻(2-4 GHz)頻率合成 器的設計,製造及測量,其中之電壓控制振盪器使用雙極性接面電晶體,場 效電晶體和變容二極體,而振盪頻率之精確及穩定則使用鎖相迴路.我們以 混成(Hybrid)微波積體電路的技術製作窄頻和寬頻兩個電壓控制振盪電 路,而後再以自行撰寫之C語言IC控制程式來控制購買之鎖相迴路IC及適當 設計之迴路濾波電路,構成低成本,小體積之頻率合成器. 窄頻2.4GHz 電壓控制振盪電路大小為12mm x 14mm,最後測得窄頻2.4GHz頻率合成器離 載波頻率在10KHz之相位雜訊為-81.17dBc/Hz,25KHz為-90.67dBc/Hz,100 KHz為-103dBc/Hz, 輸出功率大於0dBm. 寬頻2-4GHz頻率合成器之VCO 部份則分為2-3GHz BJT VCO 及3-4GHz FET VCO 兩個電路,其動作與否之 切換則以設計之直流開關電路加以控制,但此二VCO共用同一適當設計之鎖 相迴路,最後測得寬頻2-4GHz頻率合成器離載波頻率在10KHz之相位雜訊 為-73dBc/Hz,25KHz為-88.83dBc/Hz,100KHz為-108.17dBc/Hz.最後我們在 寬頻2-4GHz頻率合成器後加上一級寬頻 緩衝放大器,以改善負載拉升( Load Pulling)效應及輸出功率,其輸出功率提高約5dBm.而此緩衝放大器 大小為12mm x 12mm. In this project, the design, fabrication and measurement of a narrow band(2.4-2.484 GHz) and a broad band(2-4 GHz) hybrid integrated S-band BJT,FET VCO,PLL and synthesizer are presented. We fabricated the narrow band and broad bandVCO circit using hybrid-MIC technology. We also wrote a Turbo C program to control the PLL IC, and design a suitable loop filter for the PLL to complete these low cost,small size frequency synthesizer. The size of 2.4 GHz VCO circuit is 12mm x 14mm. The measured phase noise at 10KHz offset carrier is -81.17dBc/Hz, at 25KHz offset is -90.67dBc/Hz,at 100KHz offset is -103dBc/Hz. The output power is larger than 0 dBm. The VCO part of the broad band 2-4 GHz synthesizer is break into a 2-3 GHzBJT VCO and a 3-4 GHz FET VCO. The motion of the two VCO are switched by a designed DC switching circuit, and they use the same Phase- Locked Loop. The measured phase noise at 10KHz offset carrier is -73dBc/Hz, at 25KHz offset is -88.83dBc/Hz, at 100KHz offset is -108.17dBc/Hz. Finally, we add a broad band buffer amplifier behind this broad band synthesizer to improve the load pulling effect and boost the output power. The measured output power is raised about 5 dBm. The buffer amplifier size is 12mm x 12mm.