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標題: | 適用於多頻段/多規格通訊系統之CMOS無線接收機電路設計與實現 Design and Implementation of CMOS Wireless Receiver Front-End Circuits for Multi-band/Multi-standard Communication Systems |
作者: | Chung-Ru Wu 吳忠儒 |
指導教授: | 呂良鴻 |
關鍵字: | 射頻,無線接收機,低雜訊放大器,混波器,多頻段,多規格, radio frequency,wireless receiver,LNA,mixer,multi-band,multi-standard, |
出版年 : | 2006 |
學位: | 碩士 |
摘要: | 現今對於無線通信設備的增加需求,低成本和高度積體化將是未來射頻前端系統實現趨勢與考量。目前很多無線通信標準存在,例如GSM用於個人行動電話系統;提供不同的電子產品短距離無線連接的Bluetooth以及無線區域網路(WLANs)所採用並且提供高速率數據傳播的UWB和802.11a /b/g規格。基於電路的相似度和功能性,在單一的晶片上實現不同的無線通信規格的射頻電路是相當具有競爭潛力的研究目標。近來由於CMOS深次微米製程在技術上已有相當長足的進展,使其在高頻電路上都有相當不錯的表現,再者CMOS技術提供了極高度基頻帶類比和數位電路整合的能力,這些都顯示出利用CMOS製程實現多頻段多規格無線收發基電路的先天有利條件。
一般而言,要達成多規格/多頻段射頻電路的設計,目前多利用兩種電路架構︰寬頻性電路以及可調整性電路。這篇論文將分別就此兩種技術提出不同電路架構來實現適用於多頻段的無線前端電路。 在射頻系統中,混波器將把射頻信號降頻為中頻信號。在此論文中將提出一寬頻混波器的設計與實現方法。此混波器利用傳輸線來構成輸入端的寬頻匹配與改良式的電容性鈍化阻抗來達到應用頻寬的提升。此混波器之操作頻率從2GHz 到28GHz,量測所得到的轉換增益有12.5±1分貝,並有高達-2 dBm的輸入三接截斷點(IIP3)。在2 V電源電壓的操作條件下,此混波器所消耗的功率為40mW。 接著,一無線接收機電路利用頻率選擇機制和改良式寬頻輸入匹配來達到實現多頻段應用。低雜訊放大器的輸入端匹配利用電感電容所組成的階狀網路(LC ladder)來達成寬頻的輸入匹配。量測所得的輸入端反射係數S11從3.5 GHz在5.0 GH皆小於-10dB。轉換增益在五個不同頻帶所量測到的數據為22.2±2.4dB,整體IIP3有高於-6dBm之表現,而中頻(IF)頻帶由10MHz到55MHz。此接收機在2 V電源電壓下約有36 mW的功率消耗。 最後將介紹一個同樣為了多頻段多規格無線通訊應用所設計的低中頻架構接收機。與先前接收機的架構在設計上之差異在於接收機的輸入是利用共閘極放大器(common-gate amplifier)來實現一寬頻低雜訊放大器,並且採用了堆疊式(stacked)電感來做為輸入端RF chock以減少電感中寄生電阻造成雜訊指數的上升。改良式的可調多重共振頻率諧振式負載(multi-resonant tuned load)用來作為低雜訊放大器的頻率選擇機制。 而混波器方面將利用不同的偏壓方式來提高線性度的表現,再者為了降低散粒雜訊(flicker noise)對接收機中頻訊號的影響此電路利用pMOSFET來組成混波器與可變增益中頻放大器的部份。此可變增益放大器將用來提高整體接收機的動態範圍以符合各種不同規格的要求。 With the increasing demands on wireless communication devices, the issues of the low-cost and high-level integration are the trend for the implementation of RF front-end system. Many wireless communication standards exist, such as GSM used for personal cellular phone systems; Bluetooth for short-distance connections of different electronic products; UWB and 802.11a/b/g adopted for wireless local area networks (WLANs) and provide high data-rate transmission. It is constructive to integrate RF circuits applied for different wireless communications on a single chip because of their similarities in many wireless transceivers. With the advances in deep submicron fabrication process recently, CMOS technology is showing the potential to meet these requirements. Besides, the high integration ability with baseband analog and digital circuits of CMOS techniques makes it the best choice to achieve the multi-band/multi-standard wireless applications. Two circuit topologies are utilized to achieve this purpose: concurrent-wideband and tunable circuits. This thesis presents both circuit techniques. The mixer is used to down-converts the RF signal to low frequency IF signal. A wideband mixer design reports in this thesis with non-uniform artificial transmission lines to construct the input matching network, and modified capacitive degeneration to enhance the bandwidth, the proposed mixer has operation frequency from 2GHz to 28GHz, with 12.5±1 dB conversion gain and IIP3 larger than -2 dBm, and dissipations 40mW with 2V supply voltage. By the usage of the frequency-selection mechanisms, tunable RF receivers are implemented with different broadband input matching techniques and frequency-tuning techniques. With the proposed transformer composed of the input matching inductors, the LNA has return loss less than -10 dB from 3.5 GHz to 5.0 GHz and provides conversion gain 22.2±2.4 dB with IIP3 larger than -6 dBm from 3.0 to 5.0 GHz bands. The power consumption of the receiver is 40mW with a 2V supply voltage. The second RF receiver uses a common-gate architecture LNA and modified tunable multi-resonant tuned load. A stacked inductor adopted as the RF chock at the input port of the LNA provides high inductance with smaller chip area and shorter metal line to reduce the ohmic loss of the inductor. A modified DC bias technique for the double- quadrature mixer can enhance the linearity performance. The flicker noise is also suppressed by utilizing pMOSFETs for the mixer and the IF amplifiers. The IF amplifiers are designed to enhance the dynamic range of the receiver and the receiver can be more suitable for different wireless system applications. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/32614 |
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顯示於系所單位: | 電子工程學研究所 |
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