SlideShare a Scribd company logo

High-Efficiency RF Power Amplifiers.pptx

A tutorial on the analysis and design of highly efficient RF power amplifiers used in modern wireless communication systems.

1 of 70
Download to read offline
High Efficiency RF Power Amplifiers for
Mobile Transmitters
Firas Mohammed Ali, PhD
University of Technology, Iraq
E-mail: firas.m.ali@uotechnology.edu.iq
1
• The RF power amplifier is the final stage of a solid-state radio transmitter.
• The efficiency of the whole transmitter depends on the efficiency of the power
amplifier as it is the most power-hungry stage in the radio system.
• The battery size and life of the transmitter depends, to a large extent, on the
efficiency of the power amplifier.
Introduction
Block Diagram of a Typical Modern SDR Transmitter
2
Basic RF Power Amplifier Design Parameters
%
100


dc
out
P
P
Efficiency
RF
to
DC
%
100
)
( 


dc
in
out
P
P
P
PAE
Efficiency
Added
Power
in
out
p
P
P
G
Gain
Power 
)
(
)
(
)
(
)
( dBm
P
dBm
P
dB
G in
out
p 

High Efficiency RF Power Amplifiers are designed to maximize DC to RF
efficiency and output saturated power with minimal device power dissipation.
in
dB
IRL 

 log
20
)
(
3
Classification of RF Amplifiers
Bandwidth
Narrow Band
Amplifiers
Broadband
Amplifiers
Signal Level
Small Signal
Amplifiers
Large Signal
Amplifiers
Performance
High Gain
Amplifiers
Low Noise
Amplifiers
High Power
Amplifiers
Circuit
Construction
Microstrip
Lines
Lumped
Elements
4
Block Diagram of the RF Power Amplifier
• The input matching network is used to match the transistor input impedance with
the source impedance to increase power gain and minimize reflected power.
• The output matching network is used present the optimum load impedance at the
transistor output for maximum efficiency and output power.
• The biasing circuit is used to maintain a constant Q-point for the RF transistor and
should be isolated properly from the RF circuit.
5
Differences between Small Signal and Large Signal Power
Amplifiers
Small-Signal RF Transistor
Characterization
Small Signal
S-Parameters
Linear Circuit
Model
Ease of Measurements
High Accuracy of Modeling
Useful in Frequency
Domain Simulation
Difficulty of
Parameter
Measurements
Lower Accuracy
Useful in Time
Domain
Simulation
6
Ad

Recommended

RF Circuit Design - [Ch3-2] Power Waves and Power-Gain Expressions
RF Circuit Design - [Ch3-2] Power Waves and Power-Gain ExpressionsRF Circuit Design - [Ch3-2] Power Waves and Power-Gain Expressions
RF Circuit Design - [Ch3-2] Power Waves and Power-Gain ExpressionsSimen Li
 
Transmission lines
Transmission linesTransmission lines
Transmission linesSuneel Varma
 
RF Circuit Design - [Ch4-2] LNA, PA, and Broadband Amplifier
RF Circuit Design - [Ch4-2] LNA, PA, and Broadband AmplifierRF Circuit Design - [Ch4-2] LNA, PA, and Broadband Amplifier
RF Circuit Design - [Ch4-2] LNA, PA, and Broadband AmplifierSimen Li
 
RF Module Design - [Chapter 6] Power Amplifier
RF Module Design - [Chapter 6]  Power AmplifierRF Module Design - [Chapter 6]  Power Amplifier
RF Module Design - [Chapter 6] Power AmplifierSimen Li
 
267182869 large-signal-amplifiers-ppt
267182869 large-signal-amplifiers-ppt267182869 large-signal-amplifiers-ppt
267182869 large-signal-amplifiers-pptprasadjanga85
 
Rf power amplifier design
Rf power amplifier designRf power amplifier design
Rf power amplifier designvenkateshp100
 

More Related Content

What's hot

High efficiency power amplifiers
High efficiency power amplifiersHigh efficiency power amplifiers
High efficiency power amplifiersAbhishek Kadam
 
RF Matching Guidelines for WIFI
RF Matching Guidelines for WIFIRF Matching Guidelines for WIFI
RF Matching Guidelines for WIFIcriterion123
 
RF Circuit Design - [Ch4-1] Microwave Transistor Amplifier
RF Circuit Design - [Ch4-1] Microwave Transistor AmplifierRF Circuit Design - [Ch4-1] Microwave Transistor Amplifier
RF Circuit Design - [Ch4-1] Microwave Transistor AmplifierSimen Li
 
Design Basics on Power Amplifiers
Design Basics on Power Amplifiers Design Basics on Power Amplifiers
Design Basics on Power Amplifiers ls234
 
Power amplifier ppt
Power amplifier pptPower amplifier ppt
Power amplifier pptKrishna Ece
 
Michael john sebastian smith application-specific integrated circuits-addison...
Michael john sebastian smith application-specific integrated circuits-addison...Michael john sebastian smith application-specific integrated circuits-addison...
Michael john sebastian smith application-specific integrated circuits-addison...Đình Khanh Nguyễn
 
Design of CMOS operational Amplifiers using CADENCE
Design of CMOS operational Amplifiers using CADENCEDesign of CMOS operational Amplifiers using CADENCE
Design of CMOS operational Amplifiers using CADENCEnandivashishth
 
Network analysis of rf and microwave circuits
Network analysis of rf and microwave circuitsNetwork analysis of rf and microwave circuits
Network analysis of rf and microwave circuitsShankar Gangaju
 
Transmission lines & waveguides ppt
Transmission lines & waveguides ppt Transmission lines & waveguides ppt
Transmission lines & waveguides ppt Jayachandran T
 
Low noise amplifier csd
Low noise amplifier csdLow noise amplifier csd
Low noise amplifier csdRina Ahire
 
Active_Power_Filter
Active_Power_FilterActive_Power_Filter
Active_Power_Filteremredurna
 
Characteristics of two cavity klystron
Characteristics of two cavity klystronCharacteristics of two cavity klystron
Characteristics of two cavity klystronShubhiGupta94
 
Analog RF Front End Architecture
Analog RF Front End ArchitectureAnalog RF Front End Architecture
Analog RF Front End ArchitectureSHIV DUTT
 
Interconnect Parameter in Digital VLSI Design
Interconnect Parameter in Digital VLSI DesignInterconnect Parameter in Digital VLSI Design
Interconnect Parameter in Digital VLSI DesignVARUN KUMAR
 
Interconnect timing model
Interconnect  timing modelInterconnect  timing model
Interconnect timing modelPrachi Pandey
 

What's hot (20)

High efficiency power amplifiers
High efficiency power amplifiersHigh efficiency power amplifiers
High efficiency power amplifiers
 
RF Matching Guidelines for WIFI
RF Matching Guidelines for WIFIRF Matching Guidelines for WIFI
RF Matching Guidelines for WIFI
 
7 slides
7 slides7 slides
7 slides
 
RF Circuit Design - [Ch4-1] Microwave Transistor Amplifier
RF Circuit Design - [Ch4-1] Microwave Transistor AmplifierRF Circuit Design - [Ch4-1] Microwave Transistor Amplifier
RF Circuit Design - [Ch4-1] Microwave Transistor Amplifier
 
Design Basics on Power Amplifiers
Design Basics on Power Amplifiers Design Basics on Power Amplifiers
Design Basics on Power Amplifiers
 
Loop Antennas
Loop AntennasLoop Antennas
Loop Antennas
 
Scattering matrix
Scattering matrixScattering matrix
Scattering matrix
 
Power amplifier ppt
Power amplifier pptPower amplifier ppt
Power amplifier ppt
 
Michael john sebastian smith application-specific integrated circuits-addison...
Michael john sebastian smith application-specific integrated circuits-addison...Michael john sebastian smith application-specific integrated circuits-addison...
Michael john sebastian smith application-specific integrated circuits-addison...
 
Design of CMOS operational Amplifiers using CADENCE
Design of CMOS operational Amplifiers using CADENCEDesign of CMOS operational Amplifiers using CADENCE
Design of CMOS operational Amplifiers using CADENCE
 
Network analysis of rf and microwave circuits
Network analysis of rf and microwave circuitsNetwork analysis of rf and microwave circuits
Network analysis of rf and microwave circuits
 
Pll ppt
Pll pptPll ppt
Pll ppt
 
Rf fundamentals
Rf fundamentalsRf fundamentals
Rf fundamentals
 
Transmission lines & waveguides ppt
Transmission lines & waveguides ppt Transmission lines & waveguides ppt
Transmission lines & waveguides ppt
 
Low noise amplifier csd
Low noise amplifier csdLow noise amplifier csd
Low noise amplifier csd
 
Active_Power_Filter
Active_Power_FilterActive_Power_Filter
Active_Power_Filter
 
Characteristics of two cavity klystron
Characteristics of two cavity klystronCharacteristics of two cavity klystron
Characteristics of two cavity klystron
 
Analog RF Front End Architecture
Analog RF Front End ArchitectureAnalog RF Front End Architecture
Analog RF Front End Architecture
 
Interconnect Parameter in Digital VLSI Design
Interconnect Parameter in Digital VLSI DesignInterconnect Parameter in Digital VLSI Design
Interconnect Parameter in Digital VLSI Design
 
Interconnect timing model
Interconnect  timing modelInterconnect  timing model
Interconnect timing model
 

Similar to High-Efficiency RF Power Amplifiers.pptx

power amplifier.pptx
power amplifier.pptxpower amplifier.pptx
power amplifier.pptxudayt4
 
Electronics and Communication Engineering
Electronics and Communication EngineeringElectronics and Communication Engineering
Electronics and Communication EngineeringEkeeda
 
Unit-I Characteristics of opamp
Unit-I Characteristics of opampUnit-I Characteristics of opamp
Unit-I Characteristics of opampDr.Raja R
 
Analog & Digital Integrated Circuits - Material (Short Answers)
Analog & Digital Integrated Circuits -  Material (Short Answers) Analog & Digital Integrated Circuits -  Material (Short Answers)
Analog & Digital Integrated Circuits - Material (Short Answers) Mathankumar S
 
Electronic circuit design lab manual
Electronic circuit design lab manualElectronic circuit design lab manual
Electronic circuit design lab manualawais ahmad
 
Class e power amplifiers for qrp2 qro
Class e power amplifiers for qrp2 qroClass e power amplifiers for qrp2 qro
Class e power amplifiers for qrp2 qroDavid Cripe
 
Power amplifire analog electronics
Power amplifire analog electronicsPower amplifire analog electronics
Power amplifire analog electronicsrakesh mandiya
 
Differentiator.ppt
Differentiator.pptDifferentiator.ppt
Differentiator.pptPonnalaguRN1
 
Frequency to voltage converter.final
Frequency to voltage converter.finalFrequency to voltage converter.final
Frequency to voltage converter.finalprashant singh
 
Bjt amplifiers
Bjt amplifiersBjt amplifiers
Bjt amplifiersGastarot
 
Electrical and Electronics Engineering
Electrical and Electronics EngineeringElectrical and Electronics Engineering
Electrical and Electronics EngineeringEkeeda
 
“Microcontroller Based Substation Monitoring system with gsm modem”.
“Microcontroller Based Substation Monitoring system with gsm modem”.“Microcontroller Based Substation Monitoring system with gsm modem”.
“Microcontroller Based Substation Monitoring system with gsm modem”.Priya Rachakonda
 
Integrated Circuit Applications
Integrated Circuit ApplicationsIntegrated Circuit Applications
Integrated Circuit ApplicationsUMAKANTH22
 

Similar to High-Efficiency RF Power Amplifiers.pptx (20)

power amplifier.pptx
power amplifier.pptxpower amplifier.pptx
power amplifier.pptx
 
UNIT-3 OPAMP.pptx
UNIT-3 OPAMP.pptxUNIT-3 OPAMP.pptx
UNIT-3 OPAMP.pptx
 
Electronics and Communication Engineering
Electronics and Communication EngineeringElectronics and Communication Engineering
Electronics and Communication Engineering
 
Unit-I Characteristics of opamp
Unit-I Characteristics of opampUnit-I Characteristics of opamp
Unit-I Characteristics of opamp
 
Analog & Digital Integrated Circuits - Material (Short Answers)
Analog & Digital Integrated Circuits -  Material (Short Answers) Analog & Digital Integrated Circuits -  Material (Short Answers)
Analog & Digital Integrated Circuits - Material (Short Answers)
 
Transisitor amplifier
Transisitor amplifierTransisitor amplifier
Transisitor amplifier
 
Electronic circuit design lab manual
Electronic circuit design lab manualElectronic circuit design lab manual
Electronic circuit design lab manual
 
Class e power amplifiers for qrp2 qro
Class e power amplifiers for qrp2 qroClass e power amplifiers for qrp2 qro
Class e power amplifiers for qrp2 qro
 
Audio amplifier
Audio amplifier Audio amplifier
Audio amplifier
 
Olano
OlanoOlano
Olano
 
Power amplifiers
Power amplifiersPower amplifiers
Power amplifiers
 
Power amplifire analog electronics
Power amplifire analog electronicsPower amplifire analog electronics
Power amplifire analog electronics
 
Differentiator.ppt
Differentiator.pptDifferentiator.ppt
Differentiator.ppt
 
Frequency to voltage converter.final
Frequency to voltage converter.finalFrequency to voltage converter.final
Frequency to voltage converter.final
 
Bjt amplifiers
Bjt amplifiersBjt amplifiers
Bjt amplifiers
 
Electrical and Electronics Engineering
Electrical and Electronics EngineeringElectrical and Electronics Engineering
Electrical and Electronics Engineering
 
Power Amplifier
Power AmplifierPower Amplifier
Power Amplifier
 
LICA- DIFFERENTIAL APLIFIERS
LICA- DIFFERENTIAL APLIFIERSLICA- DIFFERENTIAL APLIFIERS
LICA- DIFFERENTIAL APLIFIERS
 
“Microcontroller Based Substation Monitoring system with gsm modem”.
“Microcontroller Based Substation Monitoring system with gsm modem”.“Microcontroller Based Substation Monitoring system with gsm modem”.
“Microcontroller Based Substation Monitoring system with gsm modem”.
 
Integrated Circuit Applications
Integrated Circuit ApplicationsIntegrated Circuit Applications
Integrated Circuit Applications
 

High-Efficiency RF Power Amplifiers.pptx

  • 1. High Efficiency RF Power Amplifiers for Mobile Transmitters Firas Mohammed Ali, PhD University of Technology, Iraq E-mail: firas.m.ali@uotechnology.edu.iq 1
  • 2. • The RF power amplifier is the final stage of a solid-state radio transmitter. • The efficiency of the whole transmitter depends on the efficiency of the power amplifier as it is the most power-hungry stage in the radio system. • The battery size and life of the transmitter depends, to a large extent, on the efficiency of the power amplifier. Introduction Block Diagram of a Typical Modern SDR Transmitter 2
  • 3. Basic RF Power Amplifier Design Parameters % 100   dc out P P Efficiency RF to DC % 100 ) (    dc in out P P P PAE Efficiency Added Power in out p P P G Gain Power  ) ( ) ( ) ( ) ( dBm P dBm P dB G in out p   High Efficiency RF Power Amplifiers are designed to maximize DC to RF efficiency and output saturated power with minimal device power dissipation. in dB IRL    log 20 ) ( 3
  • 4. Classification of RF Amplifiers Bandwidth Narrow Band Amplifiers Broadband Amplifiers Signal Level Small Signal Amplifiers Large Signal Amplifiers Performance High Gain Amplifiers Low Noise Amplifiers High Power Amplifiers Circuit Construction Microstrip Lines Lumped Elements 4
  • 5. Block Diagram of the RF Power Amplifier • The input matching network is used to match the transistor input impedance with the source impedance to increase power gain and minimize reflected power. • The output matching network is used present the optimum load impedance at the transistor output for maximum efficiency and output power. • The biasing circuit is used to maintain a constant Q-point for the RF transistor and should be isolated properly from the RF circuit. 5
  • 6. Differences between Small Signal and Large Signal Power Amplifiers Small-Signal RF Transistor Characterization Small Signal S-Parameters Linear Circuit Model Ease of Measurements High Accuracy of Modeling Useful in Frequency Domain Simulation Difficulty of Parameter Measurements Lower Accuracy Useful in Time Domain Simulation 6
  • 7. Large Signal RF Transistor Characterization Large-Signal S-Parameters (Parameters vary with signal power level as well as with frequency) Load/Source Pull Measurement (Determination of optimum load and source impedances using input/output tuners) Non-linear Large Signal Circuit Model (Contains nonlinear elements whose values depend on voltage levels) 7
  • 9. • Small Signal RF Amplifiers operate on a small linear portion of the transistor characteristic, while Power Amplifiers operate on large and usually nonlinear portion of the transistor characteristic. • Small signal high-gain RF amplifiers are usually designed for simultaneous conjugate matching at input and output ports. 9
  • 10. • In order to obtain maximum output power, typically the power amplifier is not conjugately matched. Instead, the load network is designed such that the amplifier has the correct voltage and current at the transistor output to deliver the required power. Power Amplifier Matching Considerations Comparison between maximum gain matching and maximum output power matching 10
  • 11. RF Power Devices Used in Power Amplifiers 1. Bipolar Junction Transistors (BJTs), Simplest bias circuit design. 2. Laterally Diffused MOSFETs (LDMOSFETs), high thermal conductivity. 3. GaN High-Electron Mobility Transistors (HEMTs), high breakdown voltages due to high band-gap energy and high power density. 11
  • 12. GaN RF Power Transistor Structure 12 Features 1. High Breakdown Voltages due to High Band-gap Energy. 2. High Power Density. 3. High Thermal Conductivity. 4. Low output parasitic capacitance.
  • 14. HEMT Large Signal Model 14
  • 15. Classification of RF Power Amplifiers Conventional Mode Switching Mode Harmonically Tuned Class A Class B Class AB Class C Class D Class E Class F Class F-1 Class J • In conventional mode power amplifiers, the transistor is operating as a current source. • In switching mode power amplifiers, the transistor is operating as a switch. • In harmonic-tuned power amplifiers the transistor is operating as a possibly saturated (or over-driven) current source. 15 Continuous Class F Continuous Class F-1
  • 16. Vcc 0 2Vcc 0  2 t i v t I Icq V R Vcc 0 i vin vin Vin Vb t i  2 Vp v Class A - input cosine voltage t V V v  cos in b in   t I I i cos cq    t V V v  cos cc   cc cq dc V I P  IV Pout 0.5    2 1 2 1 cq cc cq dc I I V V I I P Pout    cc /V V   1 / cq  I I .5 0   - output cosine current - output cosine current - -DC output power - fundamental output power Transfer characteristic Input voltage Output current Output voltage - collector efficiency - voltage peak factor For ideal condition of zero saturation voltage when 1   - maximum collector efficiency in Class A 16
  • 17. Vcc  2 0 2Vcc c t i v t V R Vcc 0 i vin vin Vin t 0  2 I i i1  = 90                    2 , 0 , cos cq t t t I I i  cos 0 cq I I i    I Icq cos        cos cos   t I i    cos 1 max    I I i - output current conduction angle 2 indicates its duty cycle - input cosine voltage t V V v  cos in b in   For moment with zero current For moment with maximum current Class B Transfer characteristic Output voltage Output current Input voltage 17
  • 18. Class-A,-B,-AB, -C operation modes - quiescent current as function of half-conduction angle  where  cos cq I I   • when  > 90  cos  < 0  Icq > 0 - Class AB operation mode • when  = 90  cos  = 0  Icq = 0 - Class B operation mode • when  < 90  cos  > 0  Icq < 0 - Class C operation mode  3 cos 2 cos cos 3 2 1 0      t I t I t I I i      0 0 cos cos 2 1        I t d t I I        1 1 cos cos cos 1         I t d t t I I       , cos sin 1 0               cos sin 1 1        2 1 2 1 0 1 0 1 0 1    I I P P 1   When  = 90 and .785 0 4     - Fourier series where - dc component - fundamental component - collector efficiency - maximum collector efficiency in Class B - current coefficients 18
  • 19. t 0 i v t  Imax i  = 90 K 0 L M P Vcc 2Vcc Imax For increased input voltage amplitude: Output current Input voltage Transfer characteristic Over-driven class-B RF Power Amplifier MP – cut-off region • operation in saturation, active, and cut-off regions KM – active region KL- saturation region (depression in collector current waveform) • load line represents broken line with three sections: 19
  • 20. RFC R L C0 C Vcc Vbe vin L0 In Class-E power amplifiers, transistor operates as on-to-off switch and ideal shapes of current and voltage waveforms do not overlap simultaneously resulting in 100% efficiency Class-E power amplifiers are analyzed in time domain as their current and voltage waveforms contain harmonics having specified different phase delays depending on load network configuration Basic circuit of Class-E power amplifier with shunt capacitance consists of series inductance L, capacitor C shunting transistor, series fundamentally tuned L0C0 resonant circuit, RF choke to supply dc current and load R Shunt capacitor C can represent intrinsic device output capacitance and external circuit capacitance Active device is considered as ideal switch to provide instantaneous device switching between its on-state and off-state operation conditions Class E RF Power Amplifier with shunt capacitance 20
  • 21. 21 • transistor has zero saturation voltage, zero on-resistance, infinite off- resistance and its switching action is instantaneous and lossless R C iC iR i I0 RFC L v Vcc C0 L0 Idealized assumptions for analysis: • total shunt capacitance is assumed to be linear • RF choke allows only dc current and has no resistance • loaded quality factor QL of series fundamentally tuned resonant L0C0 circuit is infinite to provide pure sinusoidal current flowing into load • reactive elements in load network are lossless • for optimum operation 50% duty cycle is used   0 2      t t v   0 2       t t d t dv     sin R R      t I t i Optimum ideal voltage conditions across switch: - sinusoidal current flowing into load Class E RF Power Amplifier with shunt capacitance
  • 22. 22 R C iC iR i I0 RFC L v Vcc C0 L0 - switch is on    0 2      t t v   0 2       t t d t dv Optimum ideal voltage conditions across switch:     0 C   t d t dv C t i       0   t           t I I t i sin R 0 or using initial condition   0 0  i  sin R 0 I I   when           sin sin R    t I t i    2   t - switch is off    0  t i            t I I t iС sin R 0                    t t t C I t d t i C t v              sin cos cos 1 R С From first optimum condition:   sin cos 2 2 3 0           t t t C I t v          Class E RF Power Amplifier with shunt capacitance
  • 23. 23 Optimum load-network parameters : -1.5 -1 -0.5 0 0.5 1 1.5 60 120 180 240 300 iR/I0 t 0 0.5 1 1.5 2 2.5 0 60 120 180 240 300 i/I0 t 0 0.5 1 1.5 2 2.5 3 3.5 0 60 120 180 240 300 v/Vcc t  R L 1.1525  R C  1 .1836 0  out 2 cc 0.5768 P V R   945 . 35 1 tan tan 1 1                         CR R L CR R L      R C V1 L I1 IR  - series inductance - shunt capacitance - load resistance Optimum phase angle at fundamental seen by switch : Load current Collector voltage Collector current Class E RF Power Amplifier with shunt capacitance
  • 24. Harmonic Tuned RF Power Amplifiers 24 F. H. Raab, “Class-E, class-C, and class-F power amplifiers based upon a finite number of harmonics,” IEEE Trans. Microwave Theory & Tech., vol. 49, no. 8, pp. 1462–1468, Aug. 2001.
  • 25. Class F RF Power Amplifier • In class F power amplifiers, the device voltage contains only odd harmonics while the device current contains even harmonics in addition to the fundamental component. This can be done by using multi-harmonic resonators. • The device terminal voltage is shaped as a square wave, and the device current is shaped as half-sinusoidal wave with 180o phase-shift between them to minimize overlapping and power dissipation. This will maximize efficiency. 25
  • 26. - fundamental current component Class F PA: Idealized Operation 2 max 1 I I  - fundamental voltage component  cc 1 4V V   max cc 1 1 out I V 2 1 I V P   - fundamental output power dc cc dc I V P  - dc supply power 100% dc   P Pout  - collector/drain efficiency Harmonic impedance conditions: dc cc 2 max cc 1 1 8 8 I V I V R Z      0 2 Imax t  i Idc Ideal voltage waveform Vcc  2 0 2Vcc t v Ideal current waveform - dc current component  max dc I I  n Z n Z odd for even for 0 n n    26
  • 27. Class F with quarter-wave transmission line half-sine collector current consisting of fundamental and even harmonics i/Idc 3.0 2.0 1.0 0 t,  300 240 180 120 60 0 v/Vcc 1.5 1.0 0.5 0 t,  300 240 180 120 60 0 2.0 rectangular collector voltage consisting of fundamental and odd harmonics Vdd Z0, /4 vin RL C0 L0 R L 2 0 R Z R   quarterwave transmission line as impedance transformer  sinusoidal current: shunt L0C0 circuit tuned to fundamental F. H. Raab, “FET Power Amplifier Boosts Transmitter Efficiency,” Electronics, vol. 49, pp. 122-126, June 1976. 27
  • 28. Class F PA with Finite Number of Harmonics  2 t i n = 1, 2 Idc 0  2 t v n = 1, 3 Vdc 0 Fourier voltage and current waveforms with third and second harmonics. L1 Cby C2 Cout Vcc L2 YL Matching circuit with high impedances at harmonics out 2 1 2 out 2 0 1 5 12 3 5 6 1 C C L L C L     Load network Circuit parameters ImYL(0) = 0 ImYL(20) =  ImYL(30) = 0     2 2 2 2 1 2 2 2 out L 1 1 Im L C L L C L C Y           50 Ω 28
  • 29. 6 2 3 1       1 Cby Cout Vcc 2 3 YL Matching circuit with high impedances at harmonics           out 2 0 1 2 3 1 tan 3 1 C Z   Circuit parameters: Harmonic impedance conditions at collector (drain): Class F PA with even current and third voltage harmonic peaking ImYL(0) = 0 ImYL(2n0) =  ImYL(30) = 0 Transmission Line Load Network Design 50 Ω 29
  • 30.  2 t n = 1, 3, 5 v  2 t i Vdc 0 Idc n = 1, 2, 4 0 Fourier voltage and current waveforms with five harmonics. Maximum Theoretical Efficiency for Class F PA with Finite No. of Harmonics 30
  • 31. Inverse Class F Power Amplifier • In inverse class F power amplifiers, the device voltage contains only even harmonics while the device current contains odd harmonics in addition to the fundamental component. This can be done by using multi-harmonic resonators. • The device terminal voltage is shaped as a half-sinusoidal wave, and the device current is shaped as a square wave with 180o phase-shift between them to minimize overlapping and power dissipation. This will maximize efficiency. 31
  • 32. - fundamental current - fundamental voltage  dc max 1 1 out 2 1 I V I V P   - fundamental output power  c I V I V P d max dc cc dc   - dc output power 100% dc   P Pout  - ideal collector/drain efficiency Idc  2 0 2Idc t i 0 2 Vmax t  v Vcc cc max 1 2 2 V V V     dc 1 4I I  Dual to conventional Class F with mutually interchanged current and voltage waveforms Inverse Class F PA with idealized operation mode Harmonic impedance conditions: out 2 cc 2 dc cc 2 d max 1 1 8 8 8 P V I V I V R Z c        n Z n Z odd for 0 even for n n    32
  • 33. Inverse Class-F with quarterwave transmission line Vdd Z0, /4 vin RL C0 L0 R1 L 2 0 1 R Z R   quarter-wave transmission line as impedance transformer  sinusoidal current: shunt L0C0 circuit tuned to fundamental RFC Vdd RL f0 3f0 5f0 (2n + 1) f0  device is driven to operate as switch  zero impedances at odd harmonic components Kazimierczuk M. K., “A new concept of class F tuned power amplifier”, Proceedings of the 27th Midwest Circuits and Systems Symposium, 1984, pp. 425428.  quarter-wave transmission line as infinite set of series resonant circuits 33
  • 34. 1 Cby Cout Vdd Zo2, 2 3 Matching circuit with high impedances at harmonics YL Zo3 Zo1 1 Inverse Class F with second harmonic current and third harmonic voltage components 4 3 3 1       Circuit parameters:                     1 out 2 0 1 2 3 1 2 tan 2 1 C Z   Load network Harmonic impedance conditions at collector/drain: ImYL(0) = 0 ImYL(30) =  ImYL(20) = 0 50 Ω  2 t v n = 1, 2 Vdc 0  2 t i n = 1, 3 Idc 0 34
  • 35. Optimum load-network resistances at fundamental frequency for different classes of operation (B) (F) 2 1 cc ) invF ( 2 8 2 R R I V R       (B) 1 cc ) F ( 4 4 R I V R     Inverse Class F : Class F : Class B : Load resistance in inverse Class F is the highest (1.6 times greater than in Class B) Less impedance transformation ratio and easier matching procedure ut P V I V R o 2 cc 1 cc ) B ( 2   35
  • 36. 36 Performance comparison between class F and inverse class F PAs Class F Inverse Class F 1. Usually is biased as class B at the pinch- off point of the RF power device. 1. Usually is biased as class AB with certain quiescent current. 2. Gives slightly lower efficiency for the same device due to higher peak drain current which increases power dissipation at the ON period. 2. Gives slightly higher efficiency for the same device due to lower peak drain current at the ON period. 3. Gives better power gain due to lower input drive power requirement. 3. Gives lower power gain due to higher input drive power requirement. 4. Can be considered as a saturated current source amplifier with the drain current being a half-sinusoidal wave. 4. Can be considered as a switching-mode power amplifier with the drain current being a square wave. 5. Requires devices with lower breakdown voltage due to lower peak drain voltage. 5. Requires devices with higher breakdown voltage due to higher peak drain voltage.
  • 37. Class J RF Power Amplifier Class J PA is a modified version of class B PA with the device current containing only two-harmonics and device voltage multiplied by a phase-shift term. 37
  • 38. - Current and Voltage Waveforms for Class J PA 38               2 cos 3 2 cos 2 1 1 ) ( max I iD ) sin 1 ).( cos 1 ( ) (        DD D V v                2 sin 2 sin cos 1 DD V DD d V j V ). 1 ( 1     2 max 1 I Id 
  • 39. Features: 1- Better Linearity 2- Broader Bandwidth Limitations: Efficiency comparable to that of Class-B (Lower than that of Class F) 39 - Fundamental and second harmonic impedances for the Class-J PA opt opt DD d d L R j R I V j I V Z         max 1 1 1 2 ) 1 ( opt DD d d L R j I V j I V Z 8 3 4 3 max 2 2 2         max 2 I V R DD opt  0 3  L Z
  • 40. 40 Classification of RF Power Amplifiers According to the Type of Modulated Signals Nonlinear PAs for constant- amplitude signals (GSM, Bluetooth) Linear PAs for variable- amplitude signals (WCDMA, QAM, OFDM) Class E Class F Class F-1 Class AB Class J Continuous Class F/F-1
  • 41. 41 Pioneers in High Efficiency RF Power Amplifier Development Frederick Raab Coined the term “Class F PA” in 1975. He developed the theoretical calculations for maximum efficiency and output power for class F PA based on any number of harmonics at device current and voltage waveforms. Andrei Grebennikov Developed several loading networks for class F and inverse class F PAs analytically using both lumped elements and transmission lines.
  • 42. 42 Marian Kazimierczuk Developer of the inverse Class F PA in 1984 using λ/4 transmission line and series resonant circuit. Steve Cripps Inventor of the Class J PA in 2006, and the Continuous Class F /F-1 PA in 2010. Nathan Sokal Inventor of the Class E PA in 1975
  • 43. 43 Characterization of the RF Power Transistor Simplified block diagram of the power amplifier • The intrinsic output capacitance of the power device can be found from the bare die model of the transistor provided by the manufacturer. A signal can be injected at the output port with a specified sweeping frequency range and the input port is short circuited to ground. A parallel resonance will occur between the device output capacitance and the DC feed inductance. This can be implemented with the aid of an advanced simulator like Keysight ADS.
  • 44. 44 Another RF Transistor Model Including the Drain Lead Stripline
  • 45. 45 Implementation of the procedure for a 900 MHz power amplifier using the GaN 6 W CGH40006P HEMT Simulated drain current versus gate- source voltage Simulated transconductance versus gate- source voltage GS D m v i g   
  • 46. 46 5 10 15 20 25 0 30 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 -0.2 1.6 VDS ID.i, A VGS =0 1 2 3 4 0 5 1 2 3 4 5 6 7 8 9 10 11 0 12 VDS Rds VGS = 0 GS D ds v i R   
  • 47. 47 Test setup to estimate the output capacitance of the chip model of the transistor
  • 48. 48 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 3200 800 3400 1000 2000 3000 4000 5000 6000 0 7000 f mag(Zd) m1 m1 f= mag(Zd)=6812.372 Max 2801.000 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 3200 800 3400 -50 0 50 -100 100 f phase(Zd) Cds = 0.64 pF
  • 49. 49 Estimation of the Parasitic Elements for the Packaged Model
  • 50. 50 0.8 1.0 1.2 1.4 1.6 1.8 0.6 2.0 5 10 15 20 0 25 freq, GHz dB(S(2,1)) dB(S(4,3)) 0.8 1.0 1.2 1.4 1.6 1.8 0.6 2.0 -8 -6 -4 -2 -10 0 freq, GHz dB(S(1,1)) dB(S(3,3)) 0.8 1.0 1.2 1.4 1.6 1.8 0.6 2.0 -30 -25 -20 -15 -10 -5 -35 0 freq, GHz dB(S(1,2)) dB(S(3,4)) 0.8 1.0 1.2 1.4 1.6 1.8 0.6 2.0 -8 -6 -4 -2 -10 0 freq, GHz dB(S(2,2)) dB(S(4,4)) Comparison between the parameters of the optimized model and the packaged transistor
  • 51. 51 Simulation of Different Power Amplifier Classes at 900 MHz Test Setup to Evaluate the Performance of the Power Amplifier
  • 52. 52 Class-A PA Voltage and Current Waveforms Class-AB PA Voltage and Current Waveforms
  • 53. 53 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 0.0 2.4 10 20 30 40 50 0 60 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 -0.4 1.2 time, nsec VD,V iD, A 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 0.0 2.4 10 20 30 40 50 0 60 -0.0 0.2 0.4 0.6 0.8 -0.2 1.0 time, nsec VD,V iD, A Class-B PA Waveforms Class-C PA Waveforms
  • 55. 55 Output RF Power versus Input Power Power Gain versus Input Power
  • 56. 56 Overdriven Class-B Power Amplifier 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 0.0 2.4 -0.2 -0.0 0.2 0.4 0.6 0.8 -0.4 1.0 time, nsec Drain Current, A 0.5 1.0 1.5 2.0 2.5 0.0 3.0 0.1 0.2 0.3 0.4 0.0 0.5 freq, GHz mag(iD) 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 0.0 2.4 10 20 30 40 50 0 60 time, nsec Drain Voltage, V 0.5 1.0 1.5 2.0 2.5 0.0 3.0 5 10 15 20 25 0 30 freq, GHz mag(VD)
  • 57. 57 Typical Class-E RF Power Amplifier Circuit at 250 MHz
  • 58. 58 Drain Voltage and Current Waveforms Drain Efficiency and PAE vs Pin Output Power vs Input Power Power Gain vs Input Power
  • 59. 59 Class J Power Amplifier 1   Drain Voltage and Current Waveforms for Class J PA 1   
  • 60. 60 Drain Efficiency and PAE versus Input Driving Power Power Gain and Output RF Power versus Input Power
  • 61. 61 Class-F PA Simulation Proposed Test Circuit to Estimate Ropt Using the Device’s Chip Model ) 30 tan( 1 1 o ds C Z             ds LC R   3 1 tan 3 1 1 3 Simulated efficiency versus RL Simulated Pout versus RL
  • 62. 62 Intrinsic Drain Voltage Intrinsic Drain Current
  • 63. 63 Efficiency versus input power level Output power in dBm and power gain in dB versus input power
  • 64. 64 Inverse Class-F Power Amplifier Simulation A configuration for the load network used to evaluate the optimum intrinsic drain impedance for inverse class F operation. ds oC Z  3 1 1                   1 1 2 3 2 1 tan 2 1 Z R R C L L ds o  
  • 65. 65 Selection of the Bias Point for the Inverse Class-F Power Amplifier Variation of drain efficiency with Input Power Level for different bias voltages Variation of power gain with Input Power Level for different bias voltages
  • 66. 66 66 Schematic diagram for the circuit used to evaluate the optimum load-line resistance for the inverse class-F PA. Variation of efficiency versus RL Simulated output power versus RL
  • 67. 67 Intrinsic drain voltage waveform Intrinsic drain current waveform Voltage and Current Waveforms for the Inverse Class-F PA
  • 68. 68 Efficiency versus input power. Output RF power versus input power Power gain versus input power. Drain efficiency versus frequency.
  • 69. 69 Practical Test Setup for RF Power Amplifiers