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10 GHz high power amplifiers
EME Conference Orebro 2015
Goran Popovic AD6IW
Available technologies
• TWT
• GaN transistors
• GaAs transistors
• Very efficient, bulky,
high voltage, x-ray
• High power density,
gain, very expensive
• Low voltage and
efficiency devices,
surplus available
GaN Transistors
• Triquint TGA2312 9-
10GHz, 48dBm 13dB
38% eff.
• Cree CMPA601C025F
6-12GHz 46.2dBm 33dB
28V 33% eff.
Sumitomo elect. SGK1011-
2A, 10dB, 33% eff.
Toshiba TGI0910-50. 31%
9dB
GaAs FET’s
• Fujitsu, Eudyna,
Sumitomo Electric
FLM0910, FLM1011
series, 3-25W 10V
• Toshiba TIM0910,
TIM1011 series
Surplus
• Alcatel
• Three stages x band amplifier
• Fujitsu FLM1011
• 3W, 8W, 12W GaAs Fet’s. In some units 15W final device
• Can be used as driver for high power amp.
Amplifier line ups
RF IN 23-25 dBm
7.5 dB 3W 7.5dB 8W
6dB 12W
7.5dB 15W
Driver amplifier
RF OUT
RF IN
RF OUT
90 deg. 3dB splitter 90 deg. 3dB combiner
7.5dB 8W
6dB 12W
7.5dB 15W
7dB 25W
3dB higher Power and
Linearity
Balanced configuration
amplifier, two amp’s
RF IN
RF OUT
7.5dB 8W
6dB 12W
7.5dB 15W
7dB 25W
6dB higher Power and
Linearity
Driver amplifier design and
simulations
Final amplifiers
50W Balanced amplifier
• 2 x FLM0910_25F
• 8dB gain
• Idq 12.8A at 10V
GaAs fet’s bias circuits
DC
Rg
Rint.
I>0
No forward current
DC
Rg
Igs
I>0
Rp
Rp< =-Vpmax/2Igsmax
For FLM0910-25F
Rp=25Ohms
Rp power dissipation (2x)
Rp=Vpmin.sqr/Rp
Forward Gate current
64mA, Reverse Gate
current -11.2mA
Approx. Rp = 400 / Psat
Rp diss = -0.5V sqr / 25
10mW use 1/4W res.
DC
Rg
DC
Rail to Rail Op amp
Totem pole configuration,
Very low output
impedance, drive
capacitive loads, and
provide GaAs FET with
forward and reverse Gate
currents
DC
470 Ohms
330 Ohms500 Ohms
-5V from ICL7660
10mA with 0.5V output
drop !
TIM0910-8
Forward Gate current
32mA
Reverse Gate current
-4.1mA
Suggested Rg 100 Ohms
200 Ohms @ -2.94V
300 Ohms @ -1.8VTypically, Tc of Pot is 200-
300ppm Variation of gate
voltage is 100-150mV over
temperature changeCommon bias circuits
published in ham radio
magazines
Issue
Low drive level the gate
current Igs is negative and
constant, but with high
level drive Igs is possitive
and can be large up to
hundreds of mA !
Control board schematics
• Four bias voltages
• 50mS sequencing
• 3W DC/DC converter
• Isolated switch
• T/R control
Implemenation and results
• 23dB gain
• 23dBm in 46.5dBm
45W Out
• PAE > 20%
• 13.5V 18A
• Unconditional stable
• Switching high side
mosfet Rds_on issue
Testing
Future developments
• Balanced amplifier with pair of
CMPA601C025 Cree GaN MMIC
• 25W each, 28V > 30dB Gain
• Multi ports power splitter-combiner
Wave guide Combiner