sharif university of technology p a lifipower amplifier

Sharif University of TechnologySharif University of Technology

P A lifiP A lifiPower AmplifierPower AmplifierInstructor:Instructor:

Dr. Ali Dr. Ali MediMedi

MMIC Course April April 20092008 1

OutlineOutlineOutlineOutline

•• IntroductionIntroductionIntroductionIntroduction•• Some Important DefinitionsSome Important Definitions

A CA C•• PA ClassesPA Classes–– LinearLinear–– NonNon--linearlinear

•• Linearization TechniquesLinearization Techniquesqq•• ConclusionConclusion

MMIC Course 2

System SchematicSystem SchematicSystem SchematicSystem SchematicRSSI/Phase Det

IQ DEMOD

LNA VGAMIXER

ADC

TX/RXDIPLEXER

DEMOD

VCO-Synth-DDS

AMPADC

IQ MOD

VGA

AMP

AMP

DAC

DAC

PA

LOG / RMSCONTROL

MIXER

CONTROL

MMIC Course 3

PA SpecificationsPA SpecificationsPA SpecificationsPA Specifications•• Gain (Gain Flatness)Gain (Gain Flatness)•• Power consumptionPower consumption•• LinearityLinearity•• Signal peak to mean ratioSignal peak to mean ratio•• BandwidthBandwidth•• BandwidthBandwidth•• Frequency band (transmit and receive)Frequency band (transmit and receive)•• Power deliveredPower delivered•• Permissible inPermissible in--band emissionband emissionPermissible inPermissible in--band emissionband emission•• Permissible outPermissible out--ofof--band emissionband emission•• Stability over VSWRStability over VSWR

–– Ability to transmit into unknown/varying loadAbility to transmit into unknown/varying loady y gy y g•• EfficiencyEfficiency

–– Minimize any lose in the form of heat & noiseMinimize any lose in the form of heat & noise•• SizeSize

Fi d th i i i h iblFi d th i i i h ibl–– Find the minimum size as much as possibleFind the minimum size as much as possible

MMIC Course 4

Peak Output PowerPeak Output PowerPeak Output PowerPeak Output Power•• Determines the range for twoDetermines the range for two--way communicationsway communicationsgg yy•• Often specified at the Often specified at the 11--dB compression pointdB compression point•• Some examples:Some examples:

Need abo tNeed abo t 11 22 W for cell lar handsets (W for cell lar handsets ( 11 km distance)km distance)–– Need about Need about 11--2 2 W for cellular handsets (~W for cellular handsets (~1 1 km distance)km distance)–– Need about Need about 100100mW for WmW for W--LAN (LAN (100 100 m)m)–– Need about Need about 1010mW for WmW for W--PAN (Bluetooth) (PAN (Bluetooth) (11--10 10 m)m)

N d b tN d b t 11 W f UWB d t kW f UWB d t k–– Need about Need about 11mW for UWB and sensor networksmW for UWB and sensor networks•• The average power transmitted may be much lower The average power transmitted may be much lower

–– Power control (slow time scale)Power control (slow time scale)–– Amplitude modulationAmplitude modulation

Ali Niknejad,UC Berkeley, EECS 290C MMIC Course 5

EfficiencyEfficiencyEfficiencyEfficiency•• RememberRemember-- COST is major driving factor!COST is major driving factor!j gj g•• The associated power supply and heat sink can be The associated power supply and heat sink can be

incrediblyincredibly expensiveexpensive•• For lower power systems (below 10mw) powerFor lower power systems (below 10mw) power•• For lower power systems, (below 10mw) ,power For lower power systems, (below 10mw) ,power

consumption of other block is important tooconsumption of other block is important too

ISSCC2007MMIC Course 6

Efficiency MeasurementEfficiency MeasurementEfficiency MeasurementEfficiency MeasurementPo <= Pin + PDCPin

PDC

Amp

•• Drain EfficiencyDrain Efficiency–– PPOUTOUT includes harmonics powerincludes harmonics power out

DP

=η

•• Power Added EfficiencyPower Added Efficiency

dcD P

η

⎟⎠⎞

⎜⎝⎛ −=

−=

GPPP

DINOUT

PA11.ηη

–– Account drive powerAccount drive power–– Could be negative for low gain!Could be negative for low gain!

⎟⎠

⎜⎝ GP D

DCPA ηη

P•• Total efficiencyTotal efficiency

•• When power gain is highWhen power gain is highinDC

ototal PP

P+

=η

p g gp g gtotalcPAE ηηη ≈≈

MMIC Course 7

High PAPRHigh PAPRHigh PAPRHigh PAPR

•• There are some ways such thatThere are some ways such thatThere are some ways ,such that…There are some ways ,such that…–– Drain modulationDrain modulation

Load modulationLoad modulation–– Load modulationLoad modulation–– RF PWMRF PWM

•• In low frequencyIn low frequency•• In low frequencyIn low frequency•• BUT, broadbandBUT, broadband

•• Some linearization schemes may reduce theSome linearization schemes may reduce the•• Some linearization schemes may reduce the Some linearization schemes may reduce the overall efficiency!!!overall efficiency!!!

MMIC Course 8

Signal TypesSignal TypesSignal TypesSignal Types•• There are two categories including: There are two categories including: g gg g

–– ConstantConstant--envelopeenvelope•• Data is in phase or frequencyData is in phase or frequency•• NonNon linear PA can be usedlinear PA can be used•• NonNon--linear PA can be usedlinear PA can be used•• Abrupt frequency or phase transitionsAbrupt frequency or phase transitions

–– SincSinc--function spectrumfunction spectrum»» Spreads signal energy over a wide BWSpreads signal energy over a wide BW»» Spreads signal energy over a wide BWSpreads signal energy over a wide BW»» Data rate will be reducedData rate will be reduced

–– NonNon--constant envelopeconstant envelopeLi PA h ld b dLi PA h ld b d•• Linear PA should be usedLinear PA should be used

•• Data is in envelope, tooData is in envelope, too•• Higher data rateHigher data rate

MMIC Course 9

Constant Envelope ModulationConstant Envelope ModulationConstant Envelope ModulationConstant Envelope Modulation

•• Information encoded in phase/frequencyInformation encoded in phase/frequencyInformation encoded in phase/frequency Information encoded in phase/frequency onlyonly

GMSK FSKGMSK FSK–– GMSK,FSKGMSK,FSK•• Power efficient amplificationPower efficient amplification

BUT, spectrally inefficientBUT, spectrally inefficient

ISSCC 2007MMIC Course 10

NonNon--Constant Envelope Constant Envelope ModulationModulation

•• Information encoded in both amplitude andInformation encoded in both amplitude andInformation encoded in both amplitude and Information encoded in both amplitude and phasephase

QPSK QAM CDMAQPSK QAM CDMA–– QPSK,QAM,CDMAQPSK,QAM,CDMA•• Spectral efficient , Spectral efficient , BUT power inefficient! BUT power inefficient!

ISSCC2007MMIC Course 11

PAPRPAPRPAPRPAPR•• Peak to average Power RatioPeak to average Power Ratiogg

–– Peak power over average powerPeak power over average power

•• PAPR is a strong function of the type of PAPR is a strong function of the type of modulation modulation

MMIC Course 12

Average EfficiencyAverage EfficiencyAverage EfficiencyAverage Efficiency

•• Important for nonImportant for non--constant envelopeconstant envelopeImportant for nonImportant for non constant envelopeconstant envelope–– There is timeThere is time--varying instantaneous efficiencyvarying instantaneous efficiency

outAVGPη

•• Modern systems uses power controlModern systems uses power controlinAVG

outAVGAVG P

=η

–– Uses as low as possible powerUses as low as possible power

MMIC Course 13

Basics of nonBasics of non--LinearityLinearityBasics of nonBasics of non LinearityLinearity

•• Large signal behavior of the semiconductorLarge signal behavior of the semiconductorLarge signal behavior of the semiconductor Large signal behavior of the semiconductor devices is nonlineardevices is nonlinear–– Power amplifiers are nonlinear systemsPower amplifiers are nonlinear systemsp yp y

•• Nonlinearity leads toNonlinearity leads to–– Generation of HarmonicsGeneration of HarmonicsGe e at o o a o csGe e at o o a o cs–– IntermodulationIntermodulation Distortion / Spectral Distortion / Spectral RegrowthRegrowth–– SNR (NPR) DegradationSNR (NPR) Degradation( ) g( ) g–– Constellation DeformationConstellation Deformation

MMIC Course 14

LinearityLinearity MeasurmentMeasurmentLinearity Linearity MeasurmentMeasurment

•• SSome ways to measure nonome ways to measure non--linearity:linearity:SSome ways to measure nonome ways to measure non--linearity:linearity:–– ACPR (Adjacent Channel Power Ratio)ACPR (Adjacent Channel Power Ratio)

EVM (Error Vector Magnitude)EVM (Error Vector Magnitude)–– EVM (Error Vector Magnitude)EVM (Error Vector Magnitude)–– Spectral MaskSpectral Mask

PP–– PP1dB1dB

–– C/I C/I NPR (N iNPR (N i P R i )P R i )–– NPR (NoiseNPR (Noise--Power Ratio)Power Ratio)

MMIC Course 15

AMAM--AM distortionAM distortionAMAM AM distortionAM distortion

System transfer function:System transfer function:

Input signal:Input signal:

System transfer function:System transfer function:

...)()()()( 33

221 +++= txtxtxty ααα

))(cos()()( tttAtx φω +=Input signal:Input signal:

Output signal:

•• AM/AM con ersion isAM/AM con ersion is

)])([)(cos()]([)( tAtttAgty ψφω ++=

Output signal:

•• AM/AM conversion is AM/AM conversion is dominated by gdominated by gmm nonnon--linearity linearity

Ali Niknejad ,UC BerkeleyMMIC Course 16

AMAM--PM DistortionPM DistortionAMAM PM DistortionPM Distortion

•• Phase shift associated with the signal amplitudePhase shift associated with the signal amplitudePhase shift associated with the signal amplitudePhase shift associated with the signal amplitude•• Introduction of unwanted phase modulation into Introduction of unwanted phase modulation into

the output signal the output signal p gp g•• Phase modulation observedPhase modulation observed

–– Depending of the input amplitude Depending of the input amplitude p g p pp g p p

•• AMAM--PM is often the result of voltage dependent PM is often the result of voltage dependent capacitorscapacitors

MMIC Course 17

AMAM--PM ConversionPM ConversionAMAM PM ConversionPM Conversion

)]([)]([

))(()( ϕω

tBCCtVCC

ttCostBVout +=

)(t

))]([(tan)(

)]([)]([

1

1 ωϕ

CR

tBRCt

tBCCtVCC out

−

−=

≈⇒=

)(tan 1 ωϕ CR≈

C = Average capacitor value at the fist harmonic

ϕ

g p

=Average phase at the fist harmonicMMIC Course 18

TX Spectrum MaskTX Spectrum MaskTX Spectrum MaskTX Spectrum Mask

MMIC Course 19

ACPRACPRACPRACPR

•• Adjacent (Alternate) Channel Power RatioAdjacent (Alternate) Channel Power RatioAdjacent (Alternate) Channel Power RatioAdjacent (Alternate) Channel Power Ratio–– Is the ratio of the power in a specified band Is the ratio of the power in a specified band

outside the signal bandwidth to theoutside the signal bandwidth to the rmsrms powerpoweroutside the signal bandwidth to the outside the signal bandwidth to the rmsrms power power in the signalin the signal

–– Widely used with modern shaped pulse digitalWidely used with modern shaped pulse digitalWidely used with modern shaped pulse digital Widely used with modern shaped pulse digital signals such as NADC and CDMAsignals such as NADC and CDMA

MMIC Course 20

EVMEVMEVMEVM

•• Error Vector Magnitude Error Vector Magnitude –– A convenient measure of how A convenient measure of how

nonlinearity interferes with thenonlinearity interferes with thenonlinearity interferes with the nonlinearity interferes with the detection processdetection process

–– the distance between the desired and the distance between the desired and actual signal vectors normalized to aactual signal vectors normalized to a

∑=

−= M

M

k

KRKVEVM 1

2)()(

actual signal vectors, normalized to a actual signal vectors, normalized to a fraction of the signal amplitudefraction of the signal amplitude

•• both peak and both peak and rmsrms errors are errors are specifiedspecified

∑=

M

k

KRV

1

2)(

Mspec edspec ed

∑

∑=

−= M

k

KR

KRKVEVM

2

1

2

)(

)()(

ISSCC 2007

∑=k

KR1

)(

MMIC Course 21

Constellation DeformationConstellation DeformationConstellation DeformationConstellation Deformation

Output Signal of Nonlinear Amplifier(with Gain- and Phase-Distortion)Input Signal

MMIC Course 22

PA Design ChallengesPA Design ChallengesPA Design ChallengesPA Design ChallengesPower Amplifier design challenges:

• Long talk time High efficiencyHigh efficiency• High data rate High linearityHigh linearity

Linear andEfficiency

enhancement

inea

rity Linear and

Efficient PA

Li LinearizationConventionalPAs

Efficiency

MMIC Course 23

C/I MeasureC/I MeasureC/I MeasureC/I Measure

•• CarrierCarrier--toto--IntermodulationIntermodulation ratioratioCarrierCarrier--toto--IntermodulationIntermodulation ratioratio–– The PA is driven with two or more carriersThe PA is driven with two or more carriers

(tones) of equal amplitude(tones) of equal amplitude(tones) of equal amplitude(tones) of equal amplitude–– IMD will be producedIMD will be produced

•• Corresponding to sums and differences ofCorresponding to sums and differences of•• Corresponding to sums and differences ofCorresponding to sums and differences ofmultiples of the carrier frequenciesmultiples of the carrier frequencies

–– A typical linear PA has a C/I of 30 dB or betterA typical linear PA has a C/I of 30 dB or better

MMIC Course 24

PA ClassesPA ClassesPA ClassesPA Classes•• Linear operationLinear operationpp

–– Classes A,B,AB and C Classes A,B,AB and C –– Amplitude modulationAmplitude modulation–– MultiMulti--carrier signalscarrier signalsgg–– Transistor works as a transducerTransistor works as a transducer–– The RF output power is proportional to the RF input powerThe RF output power is proportional to the RF input power–– Narrow band and broadband applicationsNarrow band and broadband applicationsNarrow band and broadband applicationsNarrow band and broadband applications

•• Switching mode (NonSwitching mode (Non--linear)linear)–– Classes D,E,FClasses D,E,F

ConstantConstant envelope operationenvelope operation–– ConstantConstant--envelope operationenvelope operation–– Transistor operates as a switchTransistor operates as a switch–– Narrow band applicationsNarrow band applications

MMIC Course 25

How preserve Linearity?How preserve Linearity?How preserve Linearity?How preserve Linearity?

•• BackedBacked--Off Operation of PAOff Operation of PABackedBacked--Off Operation of PAOff Operation of PA–– Simplest Way to achieve LinearitySimplest Way to achieve Linearity

Li it i i C tLi it i i C t•• Linearity improving ConceptsLinearity improving Concepts–– PredistortionPredistortion–– FeedforwardFeedforward–– EEREER–– ......

MMIC Course 26

Basic Linear PA CircuitBasic Linear PA CircuitBasic Linear PA CircuitBasic Linear PA Circuit

ISSCC 2007 GiRaFe Forum

MMIC Course 27

Class A RF Power AmplifierClass A RF Power AmplifierClass A RF Power AmplifierClass A RF Power Amplifier

DDV ( )θINvDD

( )θOUTv( )θDv

RFC

( )θINv

THVθ

( )θINv

( )θDv( )θOUTi

( )θDi( )θDvDDV

θ

( )θDi

DDV

RFC ( )θOUTv

θ( )θOUTv

θ( )θOUTi

( )θDv( )θDi

( )θOUTi 0 θ 0 θ

122

om VV

P

RV

RVP DDom

RFout 22

22

≤= 21

22

2

2

2 ≤===DD

om

DD

om

DC

RFoutDrain V

V

RV

RPPη

MMIC Course 28

Class A CharacteristicsClass A CharacteristicsClass A CharacteristicsClass A Characteristics

•• There is no harmonicThere is no harmonicThere is no harmonicThere is no harmonic–– Can be used at frequencies near Can be used at frequencies near ffmaxmax of the of the

transistortransistortransistortransistor•• Applications:Applications:

Hi h li itHi h li it–– High linearityHigh linearity–– High frequency operationHigh frequency operation

Hi h iHi h i–– High gainHigh gain–– Broadband operationBroadband operation

MMIC Course 29

Some Practical ConsiderationsSome Practical ConsiderationsSome Practical ConsiderationsSome Practical Considerations

•• Used as lowUsed as low--level driver for efficient PAslevel driver for efficient PAsUsed as lowUsed as low level driver for efficient PAslevel driver for efficient PAs•• Used for laboratory equipments Used for laboratory equipments

–– Very lowVery low--distortion amplifiersdistortion amplifiersVery lowVery low distortion amplifiersdistortion amplifiers

•• LC circuit is not necessarilyLC circuit is not necessarily–– Can operate over a wide frequency rangeCan operate over a wide frequency rangep q y gp q y g

•• No difference between small signal and class A PANo difference between small signal and class A PA•• BJTs haveBJTs have VVsatsat limits voltage swinglimits voltage swingBJTs have BJTs have VVsatsat limits voltage swinglimits voltage swing

MMIC Course 30

Class A SpecificationsClass A SpecificationsClass A SpecificationsClass A Specifications

•• High linearityHigh linearityHigh linearityHigh linearity•• Low drain efficiency of 20Low drain efficiency of 20--30%30%

ffi i f 20%ffi i f 20%•• Power added efficiency of 20%Power added efficiency of 20%•• Capable of working at higher frequencies Capable of working at higher frequencies

relative to relative to ffTT, up to ½, up to ½--1/3 of 1/3 of ffTT

•• Can amplify nonCan amplify non--constant envelope signalsconstant envelope signalsp yp y p gp g•• Capable of broadband amplificationCapable of broadband amplification

MMIC Course 31

Class A ConsiderationsClass A ConsiderationsClass A ConsiderationsClass A Considerations

T pical efficienc is lo e than 40% Typical efficiency is lower than 40% for “linear” operation

• Efficiency actually drops down when the • Efficiency actually drops down when the signal level is lower.

Output power capability (transistor utilization factor)

81222

1 maxmax

===IV

IV

IVPP o

N

Dynamic class A is attractive

8maxmaxmaxmax IVIV

y

MMIC Course 32

CLASS A RFPA PerformanceCLASS A RFPA PerformanceCLASS A RFPA PerformanceCLASS A RFPA Performance

MMIC Course 33

Class BClass BClass BClass BLower dc current

Lower power dissipation

L fLower ft

MMIC Course 34

PushPush--Pull Class BPull Class BPushPush Pull Class BPull Class B

•• Two devices are driven 180Two devices are driven 180Two devices are driven 180 Two devices are driven 180 degrees outdegrees out--ofof--phasephase

•• They are alternately activeThey are alternately active•• They are alternately active They are alternately active or cutor cut--offoff

MMIC Course 35

Class BClass BClass B Class B

•• All harmonics existAll harmonics existAll harmonics existAll harmonics exist

I I

maxI

harmonic termination:open @ w, and short @ 2w, 3w,…

ADCDC

ACQfund

III

III

,max

,max

2

<=

==

π

fundI

DCI

π

( )( )fundCEQout IVVP minmax, 21

−=1 maxIV

%5.7822max

max

max,max, ===

π

η IV

V

PP

CC

CC

DC

outc

pure sinusoidal waveformof current flow

A)l(1P A)classas(same 8

=NP

MMIC Course 36

Class AB CharacteristicsClass AB CharacteristicsClass AB CharacteristicsClass AB Characteristics

•• ConductionConduction angle is betweenangle is between 00 degree anddegree andConduction Conduction angle is between angle is between 0 0 degree and degree and 180 180 degreedegree

optLLout RRR '// <CI

tLet o ωθ ≡optLLout ,CI

maxI

CQI⎪⎩

⎪⎨⎧ ≤≤−+=

other the 022

cos)(aaIII pkCQ θθθ

pkI

CEVmaxVCEQV

CQI

cos

2cos0

2cos From

aIIaaII

pk

CQpkCQ

−

−=⇒=+

2cos1

2cos

,

2cos1

1maxmax aIIaII CQpk

−=

−=⇒ b

ba −= π2aθ ba = π2

2cos1

2coscos

)( max aII−

−=⇒

θθ

MMIC Course 37

Class C Amplifier WaveformsClass C Amplifier WaveformsClass C Amplifier WaveformsClass C Amplifier Waveforms

V ( )DDV

( )θOUTv( )RFC

( )θINv

THV

( )θINv

( )θOUTv( )θDv( )θOUTi

( )θDi

θ( )θDi

θθ

( )θi( )sinϑ−ϑ

∝RF tP

ϑ

0 θ

( )θOUTi( )θOUTv

0

( )2cos1 ϑ−∝RFoutP

( ) ( )cossinsin

41

ϑϑϑ

ϑ−ϑ== RFout

Drain PPη ( ) ( )222 cossin4 ϑϑϑ −DCP

MMIC Course 38

Class C AmplifierClass C AmplifierClass C AmplifierClass C Amplifier

•• Biased such that conduct lessBiased such that conduct lessBiased such that conduct less Biased such that conduct less than than 5050% of time% of time

•• SpecificationsSpecificationspp–– Efficiency achievedEfficiency achieved–– Large device is neededLarge device is needed–– Impractical for solidImpractical for solid--statestate

circuitcircuit

MMIC Course 39

Class C ConsiderationsClass C ConsiderationsClass C ConsiderationsClass C Considerations

•• Higher efficiency BUT lower output powerHigher efficiency BUT lower output powerHigher efficiency, BUT lower output powerHigher efficiency, BUT lower output power•• Lower output power capabilityLower output power capability

M i @ 245 2 dM i @ 245 2 d CC 0 13410 1341–– Maximum @ 245.2 degrees Maximum @ 245.2 degrees CCpp=0.1341=0.1341•• The choice of conduction angle is trade off The choice of conduction angle is trade off

betweenbetween–– Output powerOutput power–– EfficiencyEfficiency–– Power gainPower gain

MMIC Course 40

Types of Class CTypes of Class CTypes of Class CTypes of Class C

•• There are 3 typesThere are 3 typesThere are 3 typesThere are 3 types–– CurrentCurrent--Source Class C AmplifiersSource Class C Amplifiers

•• Transistor never saturatesTransistor never saturates•• Transistor never saturatesTransistor never saturates•• Acts as controlledActs as controlled--current sourcecurrent source

–– Saturated ClassSaturated Class--C AmplifiersC AmplifiersSaturated ClassSaturated Class C AmplifiersC Amplifiers•• Transistor acts in saturation region in a portion of Transistor acts in saturation region in a portion of

conductionconduction

–– Class C Mixed Mode AmplifiersClass C Mixed Mode Amplifiers

MMIC Course 41

ComparisonComparisonComparisonComparison

•• From class A to C bias From class A to C bias maxI CI Bias ConditionsBias Conditions

current will be decreasecurrent will be decrease–– Lower fLower ftt from class A to Cfrom class A to C class A

–– BUT, efficiency increasesBUT, efficiency increasesCEV

V

class AB

class B

l C maxVclass C

MMIC Course 42


MMIC Course 43


MMIC Course 44

COMPARISONCOMPARISONCOMPARISONCOMPARISON

•• Numerical value of PA under different operationNumerical value of PA under different operationNumerical value of PA under different operationNumerical value of PA under different operation

Class A Mid-Class AB

Class B Mid-class C

Class CAB C

b 0 90 180 270 360

ICQ I /2 0 41*I 0 0 0ICQ Imax/2 0.41*Imax 0 0 0

IDC Imax/2 0.44*Imax Imax/π 0.16*Ima 0x

Ifund Imax/2 0.53*Imax Imax/2 0.31*Imax

0

ηc,max 50% 60% 78.5% ~100% (~100%)

MMIC Course 45

SMPASMPASMPASMPA•• Major part of power dissipation is due toMajor part of power dissipation is due toMajor part of power dissipation is due to Major part of power dissipation is due to

transistorstransistors•• Single poleSingle pole--single through switch is usedsingle through switch is used•• Single poleSingle pole--single through switch is usedsingle through switch is used

MMIC Course 46

SMPASMPASMPASMPA

Voltage and current waveforms in a switching‐mode amplifier

MMIC Course 47

SMPASMPASMPASMPA

MMIC Course 48

SMPA IDEASMPA IDEASMPA IDEASMPA IDEA

•• Filter is usedFilter is usedFilter is usedFilter is used–– Parallel LC shuntParallel LC shunt

Series LC tunedSeries LC tuned–– Series LC tunedSeries LC tuned•• Filter increasesFilter increases

the efficiencythe efficiency

MMIC Course 49

SMPA ISMPA IdeadeaSMPA ISMPA Ideadea

•• Parallel LC filterParallel LC filterParallel LC filterParallel LC filter

MMIC Course 50

SMPA IdeaSMPA IdeaSMPA IdeaSMPA Idea

•• Series LC tuned filterSeries LC tuned filterSeries LC tuned filterSeries LC tuned filter

MMIC Course 51

General SMPA switching conditionsGeneral SMPA switching conditionsGeneral SMPA switching conditionsGeneral SMPA switching conditions

•• Two models:Two models:A B

Two models:Two models:

A iA i•• Model A is betterModel A is better2

,12C Loss cP C V f= ⋅ ⋅ ⋅ 2

,12L Loss LP L I f= ⋅ ⋅ ⋅

•• Minimzation of losses at RF requires:Minimzation of losses at RF requires:–– VVcc == 00 when switch closes at t =when switch closes at t = 00

, 2C Loss c , 2L Loss L

VVcc 0 0 when switch closes at t when switch closes at t 00•• Zero voltage switching condition (ZVS)Zero voltage switching condition (ZVS)

–– Even better: dVEven better: dVcc/dt = /dt = 00cc

MMIC Course 52

Class D Power AmplifierClass D Power AmplifierClass D Power AmplifierClass D Power Amplifier

•• Transistors act as to pole switchTransistors act as to pole switchTransistors act as to pole switchTransistors act as to pole switch•• Suffers from lossesSuffers from losses

S t tiS t ti–– SaturationSaturation–– Switching speedSwitching speed

D i iD i i–– Drain capacitorDrain capacitor•• Dissipation occursDissipation occurs

Proportional with FProportional with F–– Proportional with FProportional with F–– Limited to VHFLimited to VHF

MMIC Course 53

Other CategoriesOther CategoriesOther CategoriesOther Categories

•• Complementary Voltage Switching (CVS)Complementary Voltage Switching (CVS)Complementary Voltage Switching (CVS) Complementary Voltage Switching (CVS) CircuitCircuitT fT f C l d V lt S it hiC l d V lt S it hi•• TransformerTransformer--Coupled Voltage Switching Coupled Voltage Switching (TCVS) Circuit(TCVS) Circuit

•• TransformerTransformer--Coupled Current Switching Coupled Current Switching (TCCS) Circuit(TCCS) Circuit

MMIC Course 54

CVS Class DCVS Class DCVS Class DCVS Class D

•• Parallel LC can not beParallel LC can not beParallel LC can not be Parallel LC can not be usedused

•• In ideal conditionIn ideal conditionIn ideal conditionIn ideal condition–– Zero saturation voltageZero saturation voltage–– Zero saturation Zero saturation e o satu at oe o satu at o

resistanceresistance–– Infinite OFF resistanceInfinite OFF resistance–– Instantaneous and Instantaneous and

lossless switchinglossless switching

MMIC Course 55

CVS WaveformsCVS WaveformsCVS WaveformsCVS Waveforms

Switch capacitance limits efficiency in high frequency applicationsfrequency applications

Ali Niknejad ,UC BerkeleyMMIC Course 56

ClassClass--D and ClassD and Class--DD--11 AmplifiersAmplifiersClassClass D and ClassD and Class DD AmplifiersAmplifiers

MMIC Course 57

TCVSTCVSTCVSTCVS

MMIC Course 58

TCCSTCCSTCCSTCCS

MMIC Course 59

Class D SpecificationsClass D SpecificationsClass D SpecificationsClass D Specifications

•• Very low linearityVery low linearityVery low linearityVery low linearity–– Can not amplify nonCan not amplify non--constant envelope signalsconstant envelope signals

Hi h d i ffi i (Hi h d i ffi i (6060%)%)•• High drain efficiency (High drain efficiency (6060%)%)•• Moderate power added efficiency(Moderate power added efficiency(4040%)%)•• Can only be used for narrowCan only be used for narrow--band band

amplificationamplification•• Proper for low frequency operationProper for low frequency operation

MMIC Course 60

Class E Power AmplifiersClass E Power AmplifiersClass E Power AmplifiersClass E Power Amplifiers( )θINv

DDV

( )θv ( )θOUTv1C1L θ( )θDv

( )θINv

( )θDv

( )θDi

( )θOUTi

( )D

θ

DDVθ( )θDi

( )θOUTv1C1L( )θDv

( )θOUTi

θ( )θOUTv

00

MMIC Course 61

Class EClass EClass EClass E

•• Transistor acts as a switchTransistor acts as a switch•• ConditionsConditions

–– Turn onTurn on•• The drain voltage drops to zeroThe drain voltage drops to zero•• Zero voltage slopeZero voltage slope

T i t t i @ ffT i t t i @ ff–– Transistor current is zero @ off Transistor current is zero @ off onon–– Helps to minimize transition timeHelps to minimize transition time

–– Turn offTurn off•• Zero currentZero current•• Zero current slopeZero current slope•• Zero current slopeZero current slope

MMIC Course 62

Class EClass EClass EClass E

•• TradeTrade--off betweenoff betweenTradeTrade--off betweenoff betweenefficiency and efficiency and

iioutput harmonicoutput harmoniccontentcontent

1ω

LQRL =LR

Cω⋅

=447.5

11

⎟⎟⎠

⎞⎜⎜⎝

⎛−

+=08.2

42.11122

LQLC

ω0980≈P 098.0≈NP

MMIC Course 63

Important ConsiderationsImportant ConsiderationsImportant ConsiderationsImportant Considerations

•• Shunt capacitance is importantShunt capacitance is importantShunt capacitance is importantShunt capacitance is important–– It does not allow a fast rise of the It does not allow a fast rise of the

collector voltagecollector voltage•• Shunt capacitance is voltage Shunt capacitance is voltage

dependentdependent–– One of nonOne of non--idealitiesidealities

•• No current jump at turnNo current jump at turn--on on j pj ptransitiontransition–– Reduce the power lossReduce the power loss

MMIC Course 64

Practical ConsiderationsPractical ConsiderationsPractical ConsiderationsPractical Considerations

•• Real transistor hasReal transistor hasReal transistor hasReal transistor has–– NonNon--zero switching timezero switching time

Parasitic reactanceParasitic reactance–– Parasitic reactanceParasitic reactance–– NonNon--zero ON resistancezero ON resistance

•• Saturation voltage for BJTsSaturation voltage for BJTs•• Saturation voltage for BJTsSaturation voltage for BJTs

•• No pure sine wave current @ the outputNo pure sine wave current @ the output•• Finite QFinite Q--factor of reactive componentsfactor of reactive components•• Maximum Drain voltage is “3.6*VDD”Maximum Drain voltage is “3.6*VDD”

MMIC Course 65

Class E Amplifier Design andClass E Amplifier Design andClass E Amplifier Design and Class E Amplifier Design and EfficiencyEfficiency

•• NonNon--idealities of class Eidealities of class ENonNon idealities of class Eidealities of class E–– ON resistanceON resistance–– OffOff--transientstransients

•• Efficiency will be reducedEfficiency will be reduced

•• Normalized Output Power CapabilityNormalized Output Power Capability

7.1,6.3 max,max, ≈≈ DDDDDDS R

ViVv

098.0.

.577.0

41

2

max,max,

max,2

2max, ≈=⇒≈+

=DDS

LN

DDL iv

PP

RVP

π4

MMIC Course 66

Class F AmplifiersClass F AmplifiersClass F AmplifiersClass F Amplifiers

Harmonic manipulationHarmonic manipulation is used to shape voltage and current signals

Class F Schematic

MMIC Course 67

Class F OperationClass F OperationClass F OperationClass F Operation

MMIC Course 68

Class F OperationClass F OperationClass F OperationClass F Operation

A Parallel LC resonator is used instead of Quarter-wave length transmission line.

MMIC Course 69

Class F Power Amplifier AnalysisClass F Power Amplifier Analysis

DDfund Vv .4π

=

8 22 Vv f d

Power delivered to the load:

2,2.4

82

maxmax

2

==

==π

VvR

Vi

RV

Rv

P

DDDSDD

D

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2

,

2

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≈=⎟⎠⎞

⎜⎝⎛==

πππ

ππ

RVV

RV

Rv

P

R

DDDD

DDfundN

DDDSD

⎠⎝

MMIC Course 70

Other Type of Class FOther Type of Class FOther Type of Class FOther Type of Class F

Waveforms in a second‐harmonic peaking Class F1 amplifier

MMIC Course 71

Class F EfficiencyClass F EfficiencyClass F EfficiencyClass F Efficiency

•• In theory if you can control an infiniteIn theory if you can control an infinite•• In theory, if you can control an infinite In theory, if you can control an infinite number of harmonics, efficiency approaches number of harmonics, efficiency approaches 100%100%100%100%

MMIC Course 72

Class F DisadvantagesClass F DisadvantagesClass F DisadvantagesClass F Disadvantages

•• Output capacitance of device not naturallyOutput capacitance of device not naturallyOutput capacitance of device not naturally Output capacitance of device not naturally absorbed into network absorbed into network need inductor to need inductor to tune it outtune it outtune it outtune it out

•• Difficult to control more than Difficult to control more than 55thth harmonic harmonic resonators areresonators are lossylossy and additional lossesand additional losses… resonators are … resonators are lossylossy and additional losses and additional losses

present diminishing returns on efficiency.present diminishing returns on efficiency.

MMIC Course 73


•• Achievable Efficiencies of PAsAchievable Efficiencies of PAsAchievable Efficiencies of PAsAchievable Efficiencies of PAs

MMIC Course 74

PA CLASSIFICATIONPA CLASSIFICATIONPA CLASSIFICATIONPA CLASSIFICATION

MMIC Course 75

Traditional PA ClassificationTraditional PA ClassificationTraditional PA ClassificationTraditional PA Classification

MMIC Course 76

Summary of a few basic PA Summary of a few basic PA measures for classes Ameasures for classes A--FF

MMIC Course 77

LinearizationLinearizationLinearization Linearization TechniquesTechniquesTechniquesTechniques

MMIC Course 78

Linearization TechniquesLinearization TechniquesLinearization TechniquesLinearization Techniques

•• Linearization techniques:Linearization techniques:•• Linearization techniques: Linearization techniques: “…“… utilized in complex , expensive RF and utilized in complex , expensive RF and microwave systems but they have not yetmicrowave systems but they have not yetmicrowave systems, but they have not yet microwave systems, but they have not yet found their way into lowfound their way into low--cost portable cost portable terminals.terminals.”” B. B. RazaviRazavi, , RF MicroelectronicsRF Microelectronics..,,

•• MostMost linear PAs in portable phoneslinear PAs in portable phonesMost Most linear PAs in portable phones linear PAs in portable phones class A stages with class A stages with ““backed offbacked off””

MMIC Course 79

Linearization SchemesLinearization SchemesLinearization SchemesLinearization SchemesDC

RF INZL

RF OUT

CorrectionCorrection

DC

RF INZL

RF OUT

At Input At Output

DC

RF INZL

RF OUT

DC

Correction

DC

ZL

Correction

ZL

At Power AmpRF OUTRF IN RF IN

Correction

ZL ZLRF OUT

p

At Dynamic LoadAt Supply

MMIC Course 80

Correct Nonlinearity at InputCorrect Nonlinearity at InputCorrect Nonlinearity at InputCorrect Nonlinearity at Input

•• PredistortionPredistortionPredistortionPredistortion–– Close loop( Adaptive PreDistortion)Close loop( Adaptive PreDistortion)

Open loopOpen loop–– Open loopOpen loop•• FeedbackFeedback

–– Direct FeedbackDirect Feedback–– CartesianCartesian–– PolarPolar

MMIC Course 81

PreDistortionPreDistortionPreDistortionPreDistortion

•• RF/ IF/ base bandRF/ IF/ base bandRF/ IF/ base bandRF/ IF/ base band•• Insertion a nonlinear element before PAInsertion a nonlinear element before PA•• Amplitude and/or phase correctionAmplitude and/or phase correctionAmplitude and/or phase correction.Amplitude and/or phase correction.•• Improvement in ACPR by Improvement in ACPR by 10 10 dB is typical.dB is typical.

PAPA VoVoViVi

VoVo VoVo VoVo

ViVi ViVi ViVi

MMIC Course 82

AM/AM & AM/PM DistortionAM/AM & AM/PM DistortionAM/AM & AM/PM DistortionAM/AM & AM/PM Distortion

MMIC Course 83

Open Loop PreDistortionOpen Loop PreDistortionOpen Loop PreDistortionOpen Loop PreDistortion

•• Require Characteristics of PARequire Characteristics of PARequire Characteristics of PARequire Characteristics of PA•• Lookup table for baseLookup table for base--band or RFband or RF

iffi i iiffi i i•• Difficulties in Difficulties in –– ResolutionResolution–– TolerancesTolerances–– Long term drift in characteristicsLong term drift in characteristics

MMIC Course 84

Table Based PredistortionTable Based PredistortionTable Based PredistortionTable Based Predistortion

•• Polar Predistortion by AmplitudePolar Predistortion by AmplitudePolar Predistortion by AmplitudePolar Predistortion by Amplitude

MMIC Course 85

Table Based PredistortionTable Based PredistortionTable Based PredistortionTable Based Predistortion

•• Full Cartesian PredistortionFull Cartesian PredistortionFull Cartesian PredistortionFull Cartesian Predistortion

MMIC Course 86

Closed Loop PreDistortionClosed Loop PreDistortionClosed Loop PreDistortionClosed Loop PreDistortion

•• Difficulties in ResolutionDifficulties in ResolutionDifficulties in ResolutionDifficulties in Resolution•• Corrects for long term drift and slowly Corrects for long term drift and slowly

changing amplifier behaviors /temperaturechanging amplifier behaviors /temperaturechanging amplifier behaviors /temperature changing amplifier behaviors /temperature /etc./etc.

MMIC Course 87

PreDistortion ExamplePreDistortion ExamplePreDistortion ExamplePreDistortion Example

MMIC Course 88

Direct FeedbackDirect FeedbackDirect FeedbackDirect Feedback

•• Basic negative feedback technique to improve linearityBasic negative feedback technique to improve linearityBasic negative feedback technique to improve linearity Basic negative feedback technique to improve linearity •• High loop gain yields to better linearityHigh loop gain yields to better linearity•• Signal gain drop and excess phase shift Signal gain drop and excess phase shift •• Stability CheckStability Check

A VoVi

AVG o ==β AV

Gi β+==

1

MMIC Course 89

Cartesian FeedbackCartesian FeedbackCartesian FeedbackCartesian Feedback•• W: Bandwidth LimitationW: Bandwidth Limitation•• W: Stability concernsW: Stability concerns•• S: LowS: Low--Complexity & power efficientComplexity & power efficient•• S: Highly resistant to drift and agingS: Highly resistant to drift and aging•• Ss: Robust to poor characterization of PASs: Robust to poor characterization of PA

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MMIC Course 90

Polar FeedbackPolar FeedbackPolar FeedbackPolar Feedback•• W: Bandwidth Limitation & Stability concernsW: Bandwidth Limitation & Stability concerns•• S: LowS: Low--ComplexityComplexity•• S: Highly resistant to drift and agingS: Highly resistant to drift and aging•• Ss: Robust to poor characterization of PASs: Robust to poor characterization of PASs: Robust to poor characterization of PASs: Robust to poor characterization of PA

MMIC Course 91

Correct Nonlinearity at SupplyCorrect Nonlinearity at SupplyCorrect Nonlinearity at SupplyCorrect Nonlinearity at Supply

•• Envelope Elemination AndEnvelope Elemination AndEnvelope Elemination And Envelope Elemination And Restoration(EER)Restoration(EER)

•• Dynamic Supply/ Envelope TrackingDynamic Supply/ Envelope Tracking•• Dynamic Supply/ Envelope TrackingDynamic Supply/ Envelope Tracking

MMIC Course 92

Envelope Elimination and Restoration Envelope Elimination and Restoration (EER)(EER)(EER)(EER)

•• Decompose a Decompose a bandpassbandpass signal into an envelope signal and a phase signal into an envelope signal and a phase pp pp g p g pg p g psignalsignal )(ta

)](cos[)()( tttatv c φω +=)(tφ

•• Require no linearity in PA stage.Require no linearity in PA stage.)(φ

)(Linear amp.

)(tak ⋅Envelopedetector

)(taea a p.

)(tφlimiter SwitchingPA

VoVi)(tφ

Class D, E, F

MMIC Course 93

Envelope SignalEnvelope SignalEnvelope SignalEnvelope SignalEnvelope signal

MMIC Course 94

ClosedClosed--Loop EER ImplementationLoop EER ImplementationClosedClosed Loop EER ImplementationLoop EER Implementation

MMIC Course 95

Envelope DetectorEnvelope DetectorEnvelope DetectorEnvelope Detector

•• Non Ideal DiodeNon Ideal Diode Using this circuitUsing this circuitNon Ideal Diode Non Ideal Diode Using this circuitUsing this circuit

MMIC Course 96

Envelope AmplifierEnvelope AmplifierEnvelope AmplifierEnvelope Amplifier•• High efficiency envelope amplifier is requiredHigh efficiency envelope amplifier is requiredg y p p qg y p p q

–– Bandwidth: > 20 MHz for 5 MHz signalBandwidth: > 20 MHz for 5 MHz signal–– High CurrentHigh Current

Efficiency: >>50%Efficiency: >>50%–– Efficiency: >>50%Efficiency: >>50%

•• ProblemsProblems–– Complicated circuitComplicated circuit–– Limited bandwidthLimited bandwidth

MMIC Course 97

Influence of time alignmentInfluence of time alignmentInfluence of time alignmentInfluence of time alignment•• Misalignment between amplitude and phase pathsMisalignment between amplitude and phase pathsg p p pg p p p

–– Leads to severe signal distortonLeads to severe signal distorton–– Alignment requirements in the order of a few psec.Alignment requirements in the order of a few psec.

MMIC Course 98

Influence of time alignmentInfluence of time alignmentInfluence of time alignmentInfluence of time alignment•• Misalignment between amplitude and phase pathsMisalignment between amplitude and phase pathsg p p pg p p p

–– Leads to severe signal distortonLeads to severe signal distorton–– Alignment requirements in the order of a few psec.Alignment requirements in the order of a few psec.

MMIC Course 99

EER IssuesEER IssuesEER IssuesEER Issues•• Require Envelope amplifierRequire Envelope amplifierq p pq p p

(drain DC supply)(drain DC supply)•• Mismatch of gain and phase between two Mismatch of gain and phase between two

paths paths •• Limiter exhibits AM/PM Distortion Limiter exhibits AM/PM Distortion

Effi i f S it hi P S lEffi i f S it hi P S l•• Efficiency of Switching Power SupplyEfficiency of Switching Power Supply•• Band Width of Switching Power SupplyBand Width of Switching Power Supply•• Time alignment between the supply and RFTime alignment between the supply and RF•• Time alignment between the supply and RF Time alignment between the supply and RF

pathspaths

MMIC Course 100

Feed ForwardFeed ForwardFeed ForwardFeed Forward

•• Correct nonCorrect non--linearity at outputlinearity at outputCorrect nonCorrect non--linearity at outputlinearity at output•• Two Two loops loops

Si l C ll ti lSi l C ll ti l–– Signal Cancellation loopSignal Cancellation loop–– Distortion Cancellation loopDistortion Cancellation loop

1Φ 2τ

Signal cancellation loop Distortion cancellation loop

1τ2Φ

MMIC Course 101

Feed ForwardFeed ForwardFeed ForwardFeed Forward

•• Advantages:Advantages:Advantages:Advantages:–– WideWide bandwidth bandwidth –– Good Cancellation performanceGood Cancellation performanceGood Cancellation performanceGood Cancellation performance

•• Issues:Issues:–– Difficult to build analog delay elementsDifficult to build analog delay elementsDifficult to build analog delay elements.Difficult to build analog delay elements.–– Requires low loss output Requires low loss output ““adder/coupleradder/coupler””..–– Sensitive to amplitude and phase imbalance due to Sensitive to amplitude and phase imbalance due to p pp p

process and temperature variation..process and temperature variation..–– High complexityHigh complexity

MMIC Course 102

Adaptive Feed ForwardAdaptive Feed ForwardAdaptive Feed ForwardAdaptive Feed Forward

•• Open loopOpen loop Close loop FFClose loop FFOpen loop Open loop Close loop FFClose loop FF•• Robust to poor characterization of PARobust to poor characterization of PA

MMIC Course 103

Array of Power AmpsArray of Power AmpsArray of Power AmpsArray of Power Amps

•• Array of Power Amps are usedArray of Power Amps are usedArray of Power Amps are usedArray of Power Amps are used–– SimilarSimilar

Binary weightedBinary weighted–– Binary weightedBinary weighted

Switches

RF IN RF OUT

MMIC Course 104

Thanks for your time!Thanks for your time!Thanks for your time!Thanks for your time!

MMIC Course 105

sharif university of technology p a lifipower amplifier

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