CIRCUIT DESIGN FOR RE TRANSCEIVERS By Domine Leenaerts Philips Research Laboratories Eindhoven Johan van der Tang Eindhoven University of Technology and Cicero S. Vaucher Philips Research Laboratories Eindhoven KLUWER ACADEMIC PUBLISHERS BOSTON/DORDRECHT/LONDON
ContentsxiliPreface11.RFDESIGN:CONCEPTSANDTECHNOLOGY11.1 RFSpecifications21.1.1 Gain61.1.2 Noise101.1.3 Non-linearity141.1.4 Sensitivity141.2RFDeviceTechnology151.2.1 Characterization and Modeling15Modeling17Cut-off Frequency20MaximumOscillationFrequency21InputLimitedFrequency22OutputLimitedFrequency23MaximumAvailableBandwidth231.2.2 Technology Choice24Double Poly Devices26Silicon-on-Anything28Comparison30SiGe Bipolar Technology30RFCMOS331.3Passives341.3.1 Resistors351.3.2 Capacitors371.3.3PlanarMonolithicInductors42References432.ANTENNAS.INTERFACEANDSUBSTRATE432.1Antennas462.2BondWires492.3 Transmission Lines492.3.1 GeneralTheory512.3.2ImpedanceMatchingusingTransmissionLines542.3.3MicrostripLinesandCoplanarLines582.4BondPadsandESDDevicesvii
viiCIRCUITDESIGNFORRFTRANSCEIVERS2.4.1 Bond Pads592.4.2 ESDDevices6061ggNMOSTESDDevice64pn and np-Diode ESD Device2.5Substrate672.5.1 Substrate Bounces692.5.2 Design Techniques to Reduce the Substrate Bounces71References773.LOWNOISEAMPLIFIERS79793.1 Specification843.2BipolarLNAdesignforDCSApplicationinSOA843.2.1 Design of the LNA3.2.2Measurements933.3CMOSLNADesign94943.3.1 Single Transistor LNA95Design StepsSimulation and Measurement1013.3.2 ClassicalLNADesign104TheDesign105MeasurementResults1083.4 Evaluation108References1114.MIXERS1134.1Specification1134.2BipolarMixerDesign1184.3CMOSMixers1214.3.1ActiveCMOSMixers1224.3.2PassiveCMOSMixers1271/f-Noise in Mixer Transistors1281/f-Noise due to IFAmplifier133I/f-Noise dueto Switched-CapacitorBehavior1384.3.3ConcludingRemarks141References1425.RFPOWERAMPLIFIERS1455.1Specification1451455.1.1 Efficiency5.1.2GenericAmplifierClasses1465.1.3Heating149
ixContents1505.1.4 Linearity5.1.5Ruggedness1511515.2BipolarPADesign1605.3CMOSPADesign1665.4 LinearizationPrinciples1685.4.1 Predistortion Technique1725.4.2Phase-CorrectingFeedback1775.4.3 EnvelopeEliminationandRestoration (EER)5.4.4 CartesianFeedback180182References1856. OSCILLATORS1856.1Introduction1856.1.1 The Ideal Oscillator1866.1.2 The Non-ideal Oscillator1886.1.3ApplicationandClassification6.1.4 Oscillation Conditions1911966.1.5AmplitudeStabilization1996.2 Specifications1996.2.1 FrequencyandTuning2006.2.2 Tuning Constant and Linearity2006.2.3PowerDissipation2016.2.4PhaseNoise toCarrierRatio202Reciprocal Mixing203Signal toNoiseDegradationof FM Signals203Spurious Emission2046.2.5Harmonics2046.2.6VQMatching2056.2.7 Technology and Chip Area2066.3 LCOscillators2066.3.1Frequency,TuningandPhaseNoise207Frequency208TuningPhase Noise to CarrierRatio2092216.3.2 Topologies2236.4 RCOscillators2236.4.1 Frequency, Tuning and Phase Noise224Frequency225Tuning228Phase Noise to Carrier Ratio2296.4.2 Topologies
CIRCUITDESIGNFORRFTRANSCEIVERSX2316.5DesignExamples2316.5.1An830MHzMonolithicLCOscillator231Circuit Design233Measurements2336.5.2A10GHzI/QRCOscillatorwithActiveInductors234Circuit Design235Measurements238References2437.FREQUENCY SYNTHESIZERS2437.1 Introduction2447.2Integer-NPLLArchitecture2457.3TuningSystemSpecifications2457.3.1 TuningRange2467.3.2MinimumStepSize2467.3.3 Settling Time2477.3.4 Spurious Signals2497.3.5PhaseNoise Sidebands2517.4System-levelAspectsofPLLBuildingBlocks2517.4.1 Voltage Controlled Oscillators2527.4.2 Frequency Dividers2537.4.3Phase-frequencyDetector/Charge-PumpCombination254Polarityof theFeedback Signal254Time-domain Operation256High-frequency Limitations258SpectralComponentsof theOutputSignal2587.4.4 LoopFilter260Passive Loop Filters261ActiveLoopFilters2627.5Dimensioningof thePLLParameters2627.5.1 Open-andClosed-loopTransferFunctions2637.5.2Open-loopBandwidthfandPhaseMarginm2687.6SpectralPurityPerformance2687.6.1SpuriousReferenceBreakthrough269Effect of LeakageCurrents271EffectofMismatchintheCharge-pump2727.6.2PhaseNoisePerformance273NoisefromPLLBlocks274TheEquivalentPhaseNoiseFloor276NoisefromLoopFilterand VCO277Total PhaseNoiseat Output of thePLL
xiContents7.6.3Dimensioningof thePLLLoopFilter279280Attenuationof SpuriousBreakthrough280Phase Noise due to Loop Filter Resistor283Time Constantt2 and Capacitance C2857.7Design of programmableFrequency Dividers2857.7.1 DividerArchitectures285Dual-modulus Prescaler287BasicprogrammablePrescaler288PrescalerwithExtendedProgrammability7.7.2 Dividers in CMOS Technology290291Logic Implementation292Circuit Implementation293PowerDissipationOptimization295InputAmplifier297Sensitivity Measurements3007.8Designof PFD/CPCombinations3007.8.1TheDead-zonePhenomenon3027.8.2Architecture3037.8.3CircuitImplementation7.8.4MeasurementResults304308References313Appendices313A-Behavioral Models313ModelforaLowNoiseAmplifierModel for a Mixer314315ModelforaPowerAmplifier317About the AuthorsIndex319
PrefaceOne of the key parts in a mobile telecommunication terminal is the transceiver.The term transceiver stems from the words transmitter and receiver. Thesewords referto themain task of atransceiver.In the contextofa mobiletelecom-munication terminal, thereceivertransforms the signals comingfrom the an-tenna into signals which can then be converted into the digital domain.Thetransmitter converts the analog version of the digital data stream at basebandinto a signal at radio frequencies, and delivers this signal to the antenna with acertainamountofpower.Radio transceivers havebeen around since the 1900s,with theinventionof AM and laterFM radio broadcasting.In the 1920s,pioneers like Arm-strong developed transceiver concepts which we still use today. The frequencybands ranged from severalkHzup toa few 10o MHz.Transceivers formo-bile telecommunication started to appearin the 198Os, with thedevelopmentofDECTandGSMstandards.Theseandothertelecommunicationstandardsfor mobile telephony used instead radio frequencies between 8oo MHz and3GHz.Anotherdifference between these transceivers and those of previousgenerations is that they were integrated on silicon, instead of being made withdiscrete components. The first integrated transceivers were designed in bipolarprocesses, eventually combined with GaAs technology.The transceiver itselfconsistedofseveral ICs.With thedemand for higher data rates, attempts were made to develop wire-less data standards using concepts similar to those used in the successful mobiletelecommunication standards.To achieve high data rates,the radio frequencywas increased,resulting in the5GHzcarrierfrequencyforHiPerLAN/2(orIEEE802.11a)withdataratesupto54Mb/s.Anotherwireless standardisBluetooth (or IEEE 802.11b)where the primary goal was to obtain a standardwhichcanbeproduced atverylow cost.Due to pressure from the market economy,the trend in radiofrequencydesign is to integrate the completetransceiver (except,possibly,forthepoweramplifier) on a single substrate as a multi-chip module, or even on a single die.This integration is not simple, due to the complexity of the system, its technicalspecifications and theneedforgoodcomponents atradiofrequencies.Althoughtheactivedevices currently have RFcapabilities,this is not necessarily true forthe integrated passive components such as inductors, varactors, bond pads andxili
CIRCUITDESIGNFORRFTRANSCEIVERSxivFigure 1. Mono band GSM in 1994 (left) and dual band GSM (right) in 1999electrostaticprotectiondevices.Still,thisintegration trendachievedimpressiveresults,as canbe seeninFigure1.Themobileterminal formonobandGSMoperatedat880to910MHz,andconsistedof270components.Fiveyearslaterthedualbandsolution(900and1800MHzbands)enteredthemarketwithonly130components.Areductionof50%indiscretecomponents,50%inPCBarea,andmorethan60%inRFPCBareahadbeenachieved.Modern transceivers are built up around a few basic building blocks, namelyamplifiers,filters,mixersand oscillators.Afrequency synthesizer,togeneratethe correctlocal oscillatorfrequency,completes thetransceiver.With thesebuildingblocks several architectures can berealizedIna single-conversion technique,a single local oscillatorfrequencyis usedfordown-conversionof theRF signals.Tocircumventtheimagerejectionproblem a dual-conversion architecture can be employed.Two local oscillatorsare then used; the first one to take care of the image rejection issue and thesecondonetoeasethechannel selectionproblem.With theuseof digital computing power on chip,complex (de-)modulationis possible,leading to quadrature up-anddown-conversion architectures.Acommonly used transceiverarchitecture is thedirect-conversion architecture.The intermediate frequency is set to zero, implying that the desired signal is itsown image.Theimagerejection problem is thereforeeliminated,infirstorder.Alsonearzero-IFconceptsareused,wherethefrequencydifferencebetweenthelocal oscillatorandthedesiredfrequencyisclosetothechannelbandwidthThe(near)zero-IFarchitecturecanbefoundin,forexampleGSM,DECTand,wirelessLANfrontends
PrefaceXVSCOPEOFTHEBOOKChap. 4Chap.3Chap.2demodulator1/QADCfilterduplexerXmodulatorDACfiterPA8Chap. 5Chap.7Chap.6PLLICOFigure 2. (Near)Zero-IF transceiver architecture..The architecture includes analog-to-digitaland digital-to-analog convertersAn example of a (near)zero-IFtransceiver is depicted inFigure2.Aftertheduplexer,alownoiseamplifier(LNA)firstamplifiesthe signalsinthereceiverpath. Then quadrature mixing is performed to down-convert the RF signals toanIFfrequencyat (near)zeroHertz.Twoquadrature (90°out-of-phase)signalsfrom the local oscillator (VCO) are needed, for the realization of a (effective)mixing operation with a single positive frequency.Intermediate frequencyfiltering can be performed to attenuate adjacent and non-adjacent channels.The resulting complex base band signals are then digitized in a (quadrature)analog-to-digital converter (ADC) before demodulation can be performed. Atthe transmit side,the signals are transformed into the analogue domain bya digital-to-analog converter(DAC).Theresulting baseband signals are stillcomplex, and are by means of quadrature up-conversion converted to a realsignal at the radio frequency. Then the power amplifier (PA) boosts the signalstowards the antenna at the required power transmit level. A phase-locked loop(PLL)isneededtogenerateastableandcorrectRFfrequencyfromareferenceoscillator,mostoftena crystal oscillator.Thisbookwill discussthedesignofthe circuits needed to built a RF transceiver like the one in Figure 2.Filters,data converters, and digital (de-)modulation are however outside the scope ofthis work
xviCIRCUITDESIGNFORRFTRANSCEIVERSThe contents of this book are based on ongoing research activities in the In-tegratedTransceivers departmentat PhilipsResearchLaboratories Eindhoven,The Netherlands. Our primary goal is to find solutions to problems whicharise when a radio frequency transceiver is integrated on a single die.Closeco-operation with researchers in the IC technology groups is required, sincethe current designs are continually pushing the limits of what is possible in aparticular technology.Reflections of these co-operations will be found in thisbook.We have assumed that thereader has a basicknowledgeof analogRFdesign. This book should be seen as a follow-up of the university text bookson RF analog design.The chapters are summarized below.Chapter 1 contains detailed discussions of the basic principles of RF designand commonly-used RF terminology. RF designers need to understand thelimitsoftheusedtechnologywithrespecttotheactiveandpassivecomponents.Basic active devices terminology will be discussed, namely cut-off frequencyand maximum oscillationfrequency.Wewill then cover several technologies,ranging from standard bipolar, RF CMOS,to advanced silicon technologiessuch as Silicon-On-Anything.The chapterconcludeswithadetailed discussionoftheRFperformanceofpassiveelements.For RF applications, bringing signals onto or off the silicon is not trivial.The off-chip antenna plays an important role,as it can be considered the signalsource for the receiver and the load for the transmitter. The bond wires andbond pads may affect the RF performance of the signals and circuitry on thechip. Electrostatic discharge protection devices also heavily influence the RFperformance.These topics will be discussed in Chapter 2,together with a studyoftransmissionlines.Chapter 3 discusses the design of low noise amplifiers.With the help ofseveral design steps,thereader experiences theproblems arising when realizingthis circuit in CMOS orbipolartechnologies.Mixers and, in particular, their noise behavior are currently receiving a greatdeal of attention in the literature.Active and passivemixers will be discussedinChapter4.Integrationofpoweramplifierswith20dBmormoredeliveredpowerinsilicon technology is an ongoing research topic, and some working exampleshave recently been presented at conferences. Temperature stabilization andruggedness area few of the problems incurred whendesigning this type ofcircuit.Theseproblems will bediscussed in Chapter5.Chapter 6 will treat the design of voltage controlled oscillators for RF ap-plications; do we use RC-oscillators or LC based oscillators and how do wegenerate quadrature signals? All of these topics, including the phase noiseproblem, willbehighlighted