CIRCUIT DESIGN FOR RF TRANSCEIVERS

CIRCUIT DESIGNFORRF TRANSCEIVERS

By

and

Cicero S. VaucherPhilips Research Laboratories Eindhoven

Domine LeenaertsPhilips Research Laboratories Eindhoven

Johan van der TangEindhoven University of Technology

KLUWER ACADEMIC PUBLISHERSNEW YORK, BOSTON, DORDRECHT, LONDON, MOSCOW

eBook ISBN: 0-306-47978-8Print ISBN: 0-7923-7551-3

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Print ©2001 Kluwer Academic Publishers

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Dordrecht

To Lisanne, Nienke, and Viviane

Contents

Preface

1. RF DESIGN: CONCEPTS AND TECHNOLOGY

xiii

1.1 RF Specifications1.1.1 Gain1.1.2 Noise1.1.3 Non-linearity 10

1

126

1.1.4 Sensitivity 141.2 RF Device Technology 14

1.2.1 Characterization and Modeling 15Modeling 15Cut-off Frequency 17Maximum Oscillation FrequencyInput Limited FrequencyOutput Limited FrequencyMaximum Available Bandwidth

1.2.2 Technology ChoiceDouble Poly DevicesSilicon-on-AnythingComparisonSiGe Bipolar Technology

20212223232426283030

3334353742

RF CMOS1.3 Passives

1.3.1 Resistors1.3.2 Capacitors1.3.3 Planar Monolithic Inductors

References

2. ANTENNAS, INTERFACE AND SUBSTRATE2.1 Antennas2.2 Bond Wires2.3 Transmission Lines

2.3.1 General Theory2.3.2 Impedance Matching using Transmission Lines2.3.3 Microstrip Lines and Coplanar Lines

2.4 Bond Pads and ESD Devices

4343

464949515458

vii

viii CIRCUIT DESIGN FOR RF TRANSCEIVERS

2.4.1 Bond Pads2.4.2 ESD Devices

ggNMOST ESD Devicepn and np-Diode ESD Device

2.5 Substrate2.5.1 Substrate Bounces2.5.2 Design Techniques to Reduce the Substrate Bounces

References

59606164

676971

77

3. LOW NOISE AMPLIFIERS

3.1 Specification

3.2 Bipolar LNA design for DCS Application in SOA3.2.1 Design of the LNA3.2.2 Measurements

3.3 CMOS LNA Design3.3.1 Single Transistor LNA

Design StepsSimulation and Measurement

3.3.2 Classical LNA DesignThe DesignMeasurement Results

3.4 Evaluation

References

79

79848493949495

101104105108108

111

4. MIXERS

4.1 Specification4.2 Bipolar Mixer Design4.3 CMOS Mixers

4.3.1 Active CMOS Mixers4.3.2 Passive CMOS Mixers

1/f-Noise in Mixer Transistors1/f-Noise due to IF Amplifier1/f-Noise due to Switched-Capacitor Behavior

4.3.3 Concluding Remarks

References

5. RF POWER AMPLIFIERS5.1 Specification

5.1.1 Efficiency5.1.2 Generic Amplifier Classes5.1.3 Heating

113

113118

121122127128133138141142

145

145145146149

Contents ix

5.1.4 Linearity5.1.5 Ruggedness

5.2 Bipolar PA Design

5.3 CMOS PA Design5.4 Linearization Principles

5.4.1 Predistortion Technique5.4.2 Phase-Correcting Feedback5.4.3 Envelope Elimination and Restoration (EER)5.4.4 Cartesian Feedback

References

150151

151160166168172177180182

6. OSCILLATORS6.1 Introduction

6.1.1 The Ideal Oscillator6.1.2 The Non-ideal Oscillator6.1.3 Application and Classification6.1.4 Oscillation Conditions

6.2 Specifications6.2.1 Frequency and Tuning6.2.2 Tuning Constant and Linearity6.2.3 Power Dissipation6.2.4 Phase Noise to Carrier Ratio

Reciprocal MixingSignal to Noise Degradation of FM SignalsSpurious Emission

6.2.5 Harmonics6.2.6 I/Q Matching6.2.7 Technology and Chip Area

6.3 LC Oscillators6.3.1 Frequency, Tuning and Phase Noise

FrequencyTuningPhase Noise to Carrier Ratio

6.3.2 Topologies

6.4 RC Oscillators6.4.1 Frequency, Tuning and Phase Noise

FrequencyTuningPhase Noise to Carrier Ratio

6.4.2 Topologies

185185185186188191196

199199200200201202203203204204205

206206207208209221223223224225228229

6.1.5 Amplitude Stabilization

x CIRCUIT DESIGN FOR RF TRANSCEIVERS

6.5 Design Examples6.5.1 An 830 MHz Monolithic LC Oscillator

Circuit DesignMeasurements

6.5.2 A 10 GHz I/Q RC Oscillator with Active InductorsCircuit DesignMeasurements

References

231231231233233234235238

7. FREQUENCY SYNTHESIZERS

7.1 Introduction7.2 Integer-N PLL Architecture7.3 Tuning System Specifications

7.3.1 Tuning Range7.3.2 Minimum Step Size7.3.3 Settling Time7.3.4 Spurious Signals7.3.5 Phase Noise Sidebands

7.4 System-level Aspects of PLL Building Blocks7.4.1 Voltage Controlled Oscillators7.4.2 Frequency Dividers

243

243244245245246246247249

7.4.3 Phase-frequency Detector/Charge-Pump CombinationPolarity of the Feedback SignalTime-domain OperationHigh-frequency LimitationsSpectral Components of the Output Signal

7.4.4 Loop FilterPassive Loop FiltersActive Loop Filters

7.5 Dimensioning of the PLL Parameters7.5.1 Open- and Closed-loop Transfer Functions7.5.2 Open-loop Bandwidth and Phase Margin

7.6 Spectral Purity Performance7.6.1 Spurious Reference Breakthrough

Effect of Leakage CurrentsEffect of Mismatch in the Charge-pump

7.6.2 Phase Noise PerformanceNoise from PLL BlocksThe Equivalent Phase Noise FloorNoise from Loop Filter and VCOTotal Phase Noise at Output of the PLL

251251252253254254256258258260261

262262263268268269271272273274276277

Contents xi

7.6.3 Dimensioning of the PLL Loop FilterAttenuation of Spurious BreakthroughPhase Noise due to Loop Filter ResistorTime Constant and Capacitance

279280280283

7.7 Design of programmable Frequency Dividers7.7.1 Divider Architectures

Dual-modulus PrescalerBasic programmable PrescalerPrescaler with Extended Programmability

7.7.2 Dividers in CMOS TechnologyLogic ImplementationCircuit ImplementationPower Dissipation OptimizationInput AmplifierSensitivity Measurements

7.8 Design of PFD/CP Combinations7.8.1 The Dead-zone Phenomenon7.8.2 Architecture7.8.3 Circuit Implementation7.8.4 Measurement Results

References

285285285287288290291292293295297300300302303304308

313

313313314315

317

319

Appendices

A– Behavioral ModelsModel for a Low Noise AmplifierModel for a MixerModel for a Power Amplifier

About the Authors

Index

Preface

One of the key parts in a mobile telecommunication terminal is the transceiver.The term transceiver stems from the words transmitter and receiver. Thesewords refer to the main task of a transceiver. In the context of a mobile telecom-munication terminal, the receiver transforms the signals coming from 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 acertain amount of power.

Radio transceivers have been around since the 1900s, with the inventionof AM and later FM radio broadcasting. In the 1920s, pioneers like Arm-strong developed transceiver concepts which we still use today. The frequencybands ranged from several kHz up to a few 100 MHz. Transceivers for mo-bile telecommunication started to appear in the 1980s, with the developmentof DECT and GSM standards. These and other telecommunication standardsfor mobile telephony used instead radio frequencies between 800 MHz and3 GHz. Another difference 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 itselfconsisted of several ICs.

With the demand 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 the 5 GHz carrier frequency for HiPerLAN/2 (orIEEE 802.11a) with data rates up to 54 Mb/s. Another wireless standard isBluetooth (or IEEE 802.11b) where the primary goal was to obtain a standardwhich can be produced at very low cost.

Due to pressure from the market economy, the trend in radio frequencydesign is to integrate the complete transceiver (except, possibly, for the poweramplifier) 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 the need for good components at radio frequencies. Althoughthe active devices currently have RF capabilities, this is not necessarily true forthe integrated passive components such as inductors, varactors, bond pads and

xiii

xiv

electrostatic protection devices. Still, this integration trend achieved impressiveresults, as can be seen in Figure 1. The mobile terminal for mono band GSMoperated at 880 to 910 MHz, and consisted of 270 components. Five years later,the dual band solution (900 and 1800 MHz bands) entered the market with only130 components. A reduction of 50% in discrete components, 50% in PCBarea, and more than 60% in RF PCB area had been achieved.

Modern transceivers are built up around a few basic building blocks, namelyamplifiers, filters, mixers and oscillators. A frequency synthesizer, to generatethe correct local oscillator frequency, completes the transceiver. With thesebuilding blocks several architectures can be realized.

In a single-conversion technique, a single local oscillator frequency is usedfor down-conversion of the RF signals. To circumvent the image rejectionproblem a dual-conversion architecture can be employed. Two local oscillatorsare then used; the first one to take care of the image rejection issue and thesecond one to ease the channel selection problem.

With the use of digital computing power on chip, complex (de-)modulationis possible, leading to quadrature up- and down-conversion architectures. Acommonly used transceiver architecture is the direct-conversion architecture.The intermediate frequency is set to zero, implying that the desired signal is itsown image. The image rejection problem is therefore eliminated, in first order.Also near zero-IF concepts are used, where the frequency difference betweenthe local oscillator and the desired frequency is close to the channel bandwidth.The (near) zero-IF architecture can be found in, for example GSM, DECT and,wireless LAN front ends.

CIRCUIT DESIGN FOR RF TRANSCEIVERS

Preface

An example of a (near) zero-IF transceiver is depicted in Figure 2. After theduplexer, a low noise amplifier (LNA) first amplifies the signals in the receiverpath. Then quadrature mixing is performed to down-convert the RF signals toan IF frequency at (near) zero Hertz. Two quadrature (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). The resulting 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) is needed to generate a stable and correct RF frequency from a referenceoscillator, most often a crystal oscillator. This book will discuss the design ofthe 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.

xv

xvi

The contents of this book are based on ongoing research activities in the In-tegrated Transceivers department at Philips Research Laboratories 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 the reader has a basic knowledge of analog RFdesign. 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 thelimits of the used technology with respect to the active and passive components.Basic active devices terminology will be discussed, namely cut-off frequencyand maximum oscillation frequency. We will then cover several technologies,ranging from standard bipolar, RF CMOS, to advanced silicon technologiessuch as Silicon-On-Anything. The chapter concludes with a detailed discussionof the RF performance of passive elements.

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 studyof transmission lines.

Chapter 3 discusses the design of low noise amplifiers. With the help ofseveral design steps, the reader experiences the problems arising when realizingthis circuit in CMOS or bipolar technologies.

Mixers and, in particular, their noise behavior are currently receiving a greatdeal of attention in the literature. Active and passive mixers will be discussedin Chapter 4.

Integration of power amplifiers with 20 dBm or more delivered power insilicon technology is an ongoing research topic, and some working exampleshave recently been presented at conferences. Temperature stabilization andruggedness are a few of the problems incurred when designing this type ofcircuit. These problems will be discussed in Chapter 5.

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, will be highlighted.

CIRCUIT DESIGN FOR RF TRANSCEIVERS

Preface

Finally Chapter 7 will make use of the oscillators to realize frequency syn-thesizers for radio frequencies. Spectral purity performance will be addressed,in addition to the design of low-power frequency dividers and high speed phase-frequency detector/charge-pump combinations.

Many books, papers and internal technical notes from Philips Research con-tributed in making the presented material state-of-the-art. The authors do notpretend that this book is complete, however; each chapter could provide enoughdiscussion for a book in itself. The authors would therefore want to apologizefor any imperfections.

AcknowledgementsWe are indebted to many people for their advice, assistance, and contributionsto the development of this text; it is impossible to include all of their names.We would especially like to thank Peter de Vreede and Edwin van der Heijdenfor their contributions to the designs of the LNAs in Chapter 3. We would alsolike to thank Tirdad Sowlati, Sifen Luo and Vickram Vathulya for their helpfuldiscussions on the PA chapter. The bipolar PA design is a result of their re-search activities. Many thanks are also given to William Redman-White for hissupport on the difficult noise measurements of the mixers. We would also liketo thank Henk Jan Bergveld for contributions to Chapter 2. The Chapter on os-cillators was reviewed by Peter Baltus, Hans Hegt, Dieter Kasperkovitz, Arthurvan Roermund and Pepijn van de Ven. They provided very useful feedback.Zhenhua Wang gave substantial contributions for the section on low-power pro-grammable dividers, and Dieter Kasperkovitz, Jon Stanley and Onno Kuijkenfor the section on high speed phase-frequency detector/charge-pump combina-tions.

The authors are indebted to all reviewers for their kind assistance.

DOMINE LEENAERTS, JOHAN VAN DER TANG AND CICERO VAUCHER

xvii

GLOSSARY

xix

UnitSymbolrelative magnitude of the phase noise due to loopfilter elementsrelative amplitude of a spurious signal with respectto the carrierareaamplitude errorpower conversion gainvoltage gainamplitude of the carrier signalamplitude of a spurious signalratio of the time constants of the loop filtersmall-signal common-emitter current gaintransfer function in oscillator feedback modelcapacitancecapacitances of the loop filterdrain-bulk capacitancefixed capacitance in resonator circuitgate-drain capacitanceintrinsic gate capacitancegate-source capacitancecollector-substrate junction capacitancedrain junction capacitancecarrier to noise ratio at offset frequencynormalized carrier to noise ratiocollector-base capacitancecapacitance in parallel resonator circuitparasitic capacitanceemitter-base capacitancecapacitance with series resistancesource-bulk capacitance1–dB compression point (output referred)duty-cycle of the output pulse of a charge-pumpbandgap energydielectric constantoxide permittivityvacuum permittivitycharacteristic impedance in free space

dBc

VV

FFFFFFFFF

dBc/HzdBc/Hz

FFFFFF

dB

eVF/mF/mF/m

Description

A

b

C

xx

rms phase noise power density of main dividerphase errorequivalent synthesizer phase noise floor at the inputof the phase detectoropen-loop phase noise power density generated bythe loop filter elementsphase margin (radians in equations, degrees in fig-ures)phase noise power density of the PLL output signal“low-pass” phase noise power component of“high-pass” phase noise power component ofrms phase noise power density of phase frequencydetectorrms phase noise power density of reference dividerrms phase noise power density of free-running VCOrms phase noise power density of crystal oscillatorfrequencyresidual FMpeak frequency deviation of a carrieravailable bandwidthopen-loop bandwidth, 0 dB cross-over frequencycenter frequencyfrequency of the signal at the output of a frequencydividerfourier frequency (offset, modulation or basebandfrequency)maximum oscillation frequencyminimum oscillation frequencyoscillation frequencyoutput limited frequencyoperation frequency of the PFDinput limited frequencycut-off frequencyfrequency of crystal oscillatornoise factoroutput frequency of a PLLfigure of merit related to parameter nreflection coefficientgain

Hz

HzHzHzHzHzHzHzHz

Hz

HzHzHzHzHzHzHz

CIRCUIT DESIGN FOR RF TRANSCEIVERS

f

G

F

xxi

open-loop transfer function of a PLLavailable power gaintransconductanceminimum transconductance for oscillator startupmaximum power gain(delivered) power gaintransducer gainclosed-loop transfer function of a PLLtransfer function in oscillator feedback modelrms carrier currentcurrentamplitude of the output current of a charge pumpleakage current in the tuning line of the VCOinstantaneous output current of a charge pumptail current of a differential pairtuning currentn-th order intercept pointn-th order input referred intercept pointn-th order inter modulationmean square noise current over a bandwidth

bipolar output noise current in 1 Hz

MOS output noise current in 1 Hz

closed loop mean square noise output current in 1 Hz

Boltzmann’s constantpropagation constantCCO tuning constantrms sensitivity of for tail current variationsgain of PFD/CP combinationVCO tuning constantSSB phase noise to carrier ratio at offset freq.inductancelength of transistorwavelengthfinger length of transistorinductance in parallel resonator circuitinductance with series resistancean integernumber of oscillator stagesmain divider division ratio, integer

AAAAAAAdBdBdB

Hz/AHz/AA/radHz/V

dBc/HzHmmmHH

A/V

J/K

H (s)

I

LL

nNN

xxii

noise bandwidthnoise figuren-th order output referred intercept pointavailable powercarrier powerDC input powerdelivered powerpower dissipationinput powersource resistance noise poweroutput powerRF output powertransmitted powerphase shiftstochastic phase variablepeak phase deviation of phase modulationcharge of the electron

Q quality factorcapacitor quality factorquality factor of parallel resonator circuitinductor quality factorRC oscillator quality factorreference divider division ratio, integerresistanceresistance used in the PLL loop filtervaractor capacitance ratiobase resistanceeffective bulk resistancegate resistance (due to poly)input resistancegate resistance due to non-quasi static behaviorload resistanceoutput resistanceloss resistance in parallel resonator circuitradiation resistancesource resistanceseries resistancebase-emitter resistancesheet resistanceresistivity of metal

HzdBdBWWWWWW

dBm/HzWWWradradradC

CIRCUIT DESIGN FOR RF TRANSCEIVERS

NBWNF

RR

q

xxiii

spectral density over 1 Ohm resistorLaplace transform complex variabletwo-port scatter parametersspurious free dynamic rangesignal-to-noise ratio(absolute) temperaturehigh-pass transfer functionbase transit timelarge signal delaytime constants of the loop filtertime constant determined from spectral purity con-siderationsnormalized frequency deviation fromrms voltage noise density originated in the loop filtervoltagepeak carrier amplitudepeak voltagepeak-to-peak voltagemagnitude of the ripple voltage due to mismatch inthe CP current sourcesreverse varactor voltageripple voltage at the VCO tuning linerms voltagemean square noise voltage over a bandwidthvoltage at the tuning input of a VCOwidth of transistortwo-port admittance parametersimpedancetransimpedance of the loop filterinput impedanceload impedanceoutput impedanceoptimal noise impedancesource impedancecharacteristic impedancetwo-port impedance parametersangular frequencyopen-loop bandwidthangular modulation frequencyangular oscillation frequency

dBdBK

ssss

VVVVV

VVV

rad/srad/srad/srad/s

Vm

S(f )ss -parameterSFDRSNRT

V

W

xxiv

Alternating CurrentAdjacent Channel Power RatioAnalog/DigitalAutomatic Gain ControlAmplitude ModulationCurrent Controlled oscillator(Complementary) Metal Oxide SemiconductorCarrier to Noise RatioCharge-PumpCompression PointDecibeldB relative to the carrierDirect CurrentDigital European Cordless TelephoneD-type Flip-flopDouble PolyDynamic RangeDielectric Resonator OscillatorDouble-SidebandEnhanced Data Rates for GSM EvolutionElectromagnetic CompatibilityElectro Static DischargeFrequency-Division DuplexFrequency ModulationFigure of MeritGrounded Gate NMOS TransistorGlobal System for Mobile communicationHuman Body ModelIntegrated CircuitIntermediate FrequencyIntercept PointInput Referred Intercept PointInter ModulationImage Rejection RatioInput/OutputIn-phase/QuadratureLow Noise AmplifierLocal OscillatorLow-Pass Filter

AbbreviationsACACPRA/DAGCAMCCO(C)MOSCNRCPCPdBdBcDCDECTD-FFDPODRDRODSBEDGEEMCESDFDDFMFOMggNMOSTGSMHBMICIFIPIIPIMIRRI/OI/QLNALOLPF

CIRCUIT DESIGN FOR RF TRANSCEIVERS

xxv

Linear Time InvariantNon-Quasi StaticOutput Referred Intercept PointPower AmplifierPower Added EfficiencyPhase-Frequency DetectorPhase-Locked LoopPhase ModulationQuadrature Amplitude ModulationRoot-Mean-SquaredRadio FrequencyReceive BandSurface Acoustic WaveSpurious-Free Dynamic RangeSignal-to-Noise RatioSilicon-on-AnythingSingle-SidebandTime-Division DuplexTransmit BandUniversal Mobile Telecommunications SystemVoltage Controlled OscillatorVery High Frequency

LTINQSOIPPAPAEPFDPLLPMQAMrmsRFRX-bandSAWSFDRSNRSOASSBTDDTX-bandUMTSVCOVHF