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Unformatted text preview: ProceedingsofAsia-PacificMicrowaveConference2007 Design of L o w Noise Amplifier in Common-Gate Configuration for Ultra- Wideband App lications YaoHuang KaolandChiaHungHsieh2 1DepartmentofCommunicationEngineering,ChungHuaUniversity,HsinChuTaiwan 2Nnstitute ofCommunicationEngineering,Chiao-TungUniversity,Hsin-Chu,Taiwan Abstract-A new 3-10 GHz ultra-wide-band (UWB) low noise amplifier (LNA) isdesigned in TSMC 0.18um CMOS process. Reactive matching ofcommon gate configurationisextended to wide bandwidth using the Butterworth filter. A systematic approach todesignawide band lownoiseamplifiersisespecially emphasized. The amplifierwith on-chip filterspanning3-IOGHz delivers7dB gain,4dB noisefigure,and-2dBm inputIP3at6GHz, with power consumption 7.6mW. The input and output return loss (Si1 and S22) are verified to be less than -10dB. The comparisonsofthemeasurementresultsarealsoindicated. Indexingterm:Ultra-wideband,Low-noiseamplifier, I. INTRODUCTION Ultra-wideband communication has received great attentionsforapplicationsinshort-range,lowpower,andhigh speed wireless systems.  As approved by FCC, the bandwidthusingtheunlicensedfrequencyband from 3.1GHz to 10.6GHz. For such awide band application,thedesignof lownoiseamplifier,whichisthefirststageafterantenna,isnot an easy job. At least, three challenges of design are encountered.The50ohmwide-bandinputmatching,lownoise figure,low power consumption, flatgain,and highdynamic range. A number ofUWB LNAs in CMOS processes have been presented. Three common configurations ofdistributed amplifiers, common source with source degeneration, and common gatearewidelyusedinCMOS LNA design.[2-9]The firstoneconsumeslargepowerandarea.[2-3]Thesecondhas thesuperiornoiseperformancebyusinglosslessinductorfor bothnarrow-bandnoisefigureandmatchingoptimization.[4-6] Incontrast,thelastprovidesawidebandinputmatchingthatis insensitive to input parasitic and process variation and isolation.[7-9]Itisnotedthatthenoisefactorisindependentof o0 /T in common gate, while is linearly dependent of coo /CT in common source. [10,11]However, the return loss may bedegradedathighfrequencybandbytheinputparasitic. Owingtothegoodperformanceoflownoiseathighfrequency bandthecommongateconfigurationisemployedfortheUWB onlyiftheinputparasiticiscarefullyconsidered.Ascontrastto thepreviousworks,here,thethree-stageButterworth filteris employed,withinwhichtheinput Cgs isconvenientlyparallel- matched. II. CIRCUITDESIGN A. Overview The LNA circuit with common gate configuration is showninFig.1.Itcanbedividedintothreesections,theinput matchingfilter,currentreusedamplifierwithMOS MI andM2, and outputbufferwithMOS M3 and M4. M5 isthecurrent mirrorforbiasing. The inputimpedancetothecommon gate configuration in Ml is roughly equal to Zin 1/(gm+ jWCgs) At low frequency the impedance becomes Zin 1 I/ g., whichisdesignedtobeequalto50ohm....
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