Components & Subsystems New generations of RF Amplifiers : from system requirements to technologies...

Components & Subsystems

New generations of RF Amplifiers:from system requirements to technologies

Michel Caplot, Christian Robert, Michel Grezaud, Bernard Darges and Pascal Ponard

cw RF Workshop – CERN – March 2008

Components & Subsystems2

System requirements (1)

From System requirements to Technologies….and not the opposite way

System requirements do include technical performance but are not limited to these performance

Systems requirements should cover system life time

Cost of a system is not limited to purchasing cost: it clearly include Life Cycle Costs (LCC)

• Purchasing cost• Maintenance cost• System evolution cost• Supplier support cost• Spare part cost• ……


System requirements (2)

Systems Requirements

Technical performance

LCC including availability of spare parts over 2 or 3 decades

System architecture

System reliability

System availability (fault tolerance, graceful degradation, maintainability, testability, …)


Architectures (1)

Large klystron based RF amplifiers

Multi-IOT based RF amplifiers

High powerFew items to maintainCentralized architecture

Lower power at each stageEasy replacementDecentralized architecture with local control


Multi-coupled IOT based RF amplifiers

Architectures (2)

Multi-coupled Solid State based RF amplifiers

Coupling lossesGraceful degradationEasy replacement

Coupling lossesLow voltageObsolescence management


Architectures (3)

Architecture should not take into account technologies

Architecture is strongly dependent on requirements

Solid State vs. Electron Device architectures : really a debate ?

Solid State Electron Devices

Low voltage High voltage

Graceful degradation but coupling losses Some possible graceful degradation

Obsolescence management Few suppliers but existing (!!!)

Components not driven by science marketAbility to produce components some decades after system start

LCC (design evolution due to new components) LCC

In both cases, experienced high power RF designers are mandatory !!!


Electron device evolution - Klystrons & IOTs (1)

KlystronsKlystrons

1 GHz 10 GHz 100 GHz

10 MW

1 MW

100 kW

10 kW

IOT

CWKlystrons

PulsedKlystrons

MBK

EIK

µs Klystrons

1 kW

Radiotherapy SecurityIndustry

Radiotherapy SecurityIndustry

ScientificAccelerators& Fusion


BroadcastBroadcast

DefenseDefense

<P>

f

Ppeak

IOTsIOTs


Electron device evolution – Triodes & Tetrodes (2)

DiacrodesDiacrodes1 MW

100 kW

10 kW

10 MHz 100 MHz 1 GHz1 MHz

TVTV

DiacrodesInductionInduction

LaserLaser

RadioRadio

Triodes & tetrodes



ScientificAcceleratorsScientificAccelerators

Triodes & TetrodesTriodes & Tetrodes


Electron device evolution – Solid State Device (3)

Solid State amplifiersSolid State amplifiers

1 W

1 kW

1 MW

Si/GaAs

PWM (S-class)

E classAB

classF class

PWM (S class)

C (D) class

AB class

C classA class

Si/SiC/GaN

1 MHz 1 GHz


Diacrode - A major evolution for tetrode technology (1)

Cathode

ControlGrid

ScreenGrid

Anode

The end capacitance is mainly done in this area

K

G1

G2A

K

G1

G2A

K

G1

G2A

K

G1

G2A

K

G1

G2AK

G1

G2AK

G1

G2A

K

G1

G2AK

G1

G2AK

G1

G2A

Two tetrodes

K

G1

G2A

K

G1

G2A

K

G1

G2A

K

G1

G2A

K

G1

G2AK

G1

G2A

K

G1

G2AK

G1

G2A

One Diacrode


Diacrode - A major evolution for tetrode technology (2)

0

0,2

0,4

0,6

0,8

1

1,2

1,4

1,6

1,8

20 30 40 50 60 70 80 90

Tetrode DiacrodeFrequency - MHz

cw Power - MW VSWR = 2.0:1

Both tubes with the same cathode


Solid State – Amplifier Class of Operation Impact (1)

100%

A

AB

B

C

D98%

0.1

Frequency, MHz

75%

65%

55%

25%

1 10 2713

80%

Thales new design

Si MOSFET Technology

500100

Am

pli

fie

r C

las

s o

f o

pe

rati

on

Eff

icie

nc

y,

%


Solid State – Amplifier structure Impact (2)

Si LDMOS Technology (low frequency)

No required tuning or adjustment90 % SMT technologyLast MOSFET technologyRoHS compliance

In case of component technology evolution, Pallets arechanging but not Case Interface and not Racks

Pallet

Case

Racks

10 kWComplete rack

600 WComplete rack


Solid State – GaN device for high frequency (3)

KORRIGAN : a GaN foundry for Europe

GaN TECHNOLOGY

RF power density x 10 Output power x 10 Power added efficiency x 2 Junction temperature > 250°C Voltage supply > 28V


Solid State – GaN device for high frequency (4)

Substrates

Epitaxy

Process

DieBank

AssemblyTest

FinalProduct

Delivery

CTH, ISOM, CIDA, PTOU.Roma TV, CNR IFN

GaN HEMT FoundriesSELEX, UMS (<-Tiger), QinetiQ

TNO, IRCOM, CTH

System HousesELT, SELEX, Thales,

Indra, EMW, SAAB, BAE ISOM

TNO

GaN epi-wafersPicogiga, QinetiQ

LiU, Tiger, ULE

U.Padova, ISOM, CIDA

NORSTEL

KORRIGAN : a GaN foundry for Europe


IOTs – Modularity based design (1)

DiamondTH793 IOTs450-850 MHz80 kW cw

TH713 IOTsL band16 kW cw


IOTs – Modularity based design (2)

Combined RF Output

Couplingcavity

Modularity allows for Fault tolerance through graceful degradation, due to the operation of each RF source at a lower power: in case of one source failure, two remaining can supply full power


Conclusion

New generations of RF amplifiers should be defined by System Requirements that include technical performance but also system operation requirements and Life Cycle Costs (and not only Purchasing Cost)

There is not a debate between Solid State and Electron devices: based on system requirements, technological answers may be based on a unique type or on a combination of technologies

Both Solid State and Electron devices have evolutions. SSD design based amplifier must incorporate an architecture that allows to mix different solid state technologies in order to take into account that science is not the market driver

Components & Subsystems New generations of RF Amplifiers : from system requirements to technologies...

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