Last evolutions on RF SSPA technology

Cedric SCHANN /Olivier GONELLA

March 2013

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• Recent history of power RF transistors

Last evolutions on RF SSPA technology

• A few words about our experience in SSPAs

• Focus on developments on the L band

• Focus on developments at 325 MHz

• Focus on developments at 162.5 MHz

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Recent history of power RF transistors

Year Transistor P/N Power Gain Max frequency Rth Efficiency

1995 MRF157 600W CW 20dB 80MHz 0.13°C/W 45% 30MHz

1998 MRF151 300W CW 15dB 175MHz 0.35°C/W 60% 175MHz

2003 LR301 300W CW 10dB 350 MHz 0.38°C/W 50% 350 MHz

2005 SD2942 350W CW 18dB 250MHz 0.35°C/W 60% 175MHz

2008 MRF6VP11KHR6 1000W pulse 26dB 130MHz 0.13°C/W 70% 100MHz

2009 MRF6VP41KHR6 1000W pulse 20dB 450MHz 0.15°C/W 64% 450MHz

2009 BLF578 1000W CW 26dB 500 MHz 0.14°C/W 75% 108MHz

2011 MRFE6VP61K25HR6 1250W CW 23dB 600MHz 0.15°C/W 75% 230MHz

2011 BLF578XR 1200W CW 26dB 500MHz 0.14°C/W 75% 108MHz

600W CW 20dB 60% 500MHz

2013 BLF178XRS 1200W CW 23dB 130MHz 0.11°C/W 80% 108MHz

1400W pulse 28dB 108MHz 0.11°C/W 72% 108MHz

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Our RF team has built more than 20,000 pulsed amplifiers, mostly

broadband, for internal use (MRI and NMR) since the early 80s.

Frequencies ranging from 6MHz to 1GHz and powers up to 2Kw.

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A few words about our expertise on SSPAs

15-400MHz 150W 20ms/10%

15-400 MHz 1kW 100ms/5%

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Since 2008, our RF Team proposes solutions for high power CW/Pulse RF Amps. Frequencies ranging from 88 MHz to 1500MHz.

Synergy with our Power Electronics department.

Installed turn-key systems up to 35kW embedding Bruker power supplies

A few words about our expertise on SSPAs

Running Installations : HZDR Up to 100kW/1.3GHz DESY 22x400W pulse / 1.3GHz IAP Up to 42kW / 87.5&175MHz CORNELL 5kW / 1.3GHz prototype GANIL Up to 55kW / 88MHz FERMILAB 10kW / 325MHz Daresbury, CEA, IPN, LAL, JLAB, TRIUMF…

Scheduled deliveries : HZB 15kW/1.3GHz FERMILAB 2x75kW / 162.5MHz GANIL Up to 290kW / 88MHz IPN/GSI 3x45kW Pulsed/ 325MHz

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Last developments at 1300MHz

8 x 10 kW CW 1.3GHz linear transmitters

HZDR Dresden end of 2011

RF out

RF in

28V DC in

1.2kW modules based on 150W transistors. Individual protection by circulators.

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Summer 2010 :

NXP and Freescale announce a 50V LD-MOS technology at 1300MHz.

End 2010 :

- NXP releases the BLF6G13L-250P 50V/250W

- Freescale releases the MRF6V13250H 50V/230W

both above 50% efficiency at nominal power.

Early 2011 :

- NXP stopped the introduction process because of excessive thermal stress of the transistor (Rth=0.44°C/W).

- The Freescale device shows significant phase vs input power variation.

Spring 2011 :

- NXP releases a thermally enhanced version of its device (Rth=0.26°C/W).

Last developments at 1300MHz

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Last developments at 1300MHz

1st application of the new device :

5 kW CW 1.3GHz linear transmitter

Cornell University installed 12/2011 RF out

RF in

50V DC in

1.7kW modules based on 250W transistors protected by circulators

2 x 16U 19” racks

3 x RF modules

1 x 150W RF driver

1 x 12kW 50V DC power supply

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The transmitter is used at nominal power (5kW), occasionally with VSWR

Thermal issue detected after 5 months !

5kW transmitter, thermal issue

Insufficient cooling of the drain lead

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5kW transmitter, thermal issue

Solution : The 3 RF modules + 1 spare were upgraded in November/December 2012. new board layout to optimize the drain lead heat dissipation Drain lead temperature is kept at 70°C max (145°C before the modification) The complete 5kW transmitter is up and running since week 2/2013.

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• 15kW CW & Pulse (@0.5dB/dB) transmitter for HZB Berlin

• 17kW CW & Pulse Saturated Output Power

• 10 x 1.7kW modules • Waveguide output at the top (Other possibilities)

• Embedded DC power supply • Cabinets : 2.20m H x 0.60m W x 1.00m D • Power/footprint : 25kW/m²

• Delivery planned Q3 2013

Last developments at 1300MHz

Current project based on this new technology

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• 30kW CW transmitter

• 2 x 10 x 1.7kW modules • Waveguide output at the top

• Embedded DC power supplies • Cabinets : 2.20m H x 1.20m W x 1.00m D • Power/footprint : 25kW/m²

Last developments at 1300MHz

Possible evolution

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Lower frequency applications benefit also from increased transistors capabilities.

Last developments at 325MHz

The BLF578 has a 1200W peak power capability. We believe it is safe to keep about 30% margin to operate it in safe and reliable conditions. This allows the transistor to cope with reasonnable VSWR levels.

Example of a 2x3kW pulsed module

developped for IPN/GSI (FAIR Project)

- 8 x transistors

- Individual circulators

- Printed radial combination

- 65% efficiency

- ECO-MODE (BLK capability 2µs delay min)

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3kW module @30% max power handles ∞ VSWR

325MHz Applications

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0 45 90 135 180 225 270 315 360

Cu

rren

ts (

A)

Phase (°)

Transistors currents

TR1

TR2

TR3

TR4

Variable length

+/-15% drain current even though the transistors are circulator protected

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• 45kW pulsed transmitter for IPN/GSI (FAIR Project)

• 8 x 6kW modules (2ms/1%) • 3˝1/8 coax output at the top

• Embedded DC switched power supplies • Cabinets : 1.85m H x 2x0.80m W x 1.00m D • Power/footprint : 28kW/m²

• Delivery planned Q4 2013

Last developments at 325MHz

Current project based on this new technology

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Last developments at 162.5 MHz

Specific drop-in circulators have developped on Bruker request for this application

Tested up to 700W CW.

700W CW pallet at 162.5MHz 70% efficiency

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• 75kW CW transmitter for Fermilab • 16 x 5kW modules • 6˝1/8 coax output at the top • 4 embedded DC switched power supplies • footprint : 2.20m H x 2.40m W x 1.00m D • Power/footprint : 30kW/m² • Delivery planned Q4 2013

Last developments at 162.5 MHz Current project based on this new technology

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