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Technology Perspective and
results with mHEMTs
Jan Geralt Bij de Vaate
ASTRON
wide band low noise receiver
JGBdV
Specification
R Schillizi et. al. Sept. ‘07
• Tinstrument= 40K (excluding sky noise), goal 30K
• BW
70MHz – 1.0 GHz (two systems)
• Survey speed
~1/T2
• Sensitivity
~1/T
wide band low noise receiver
SKADS Workshop 2007
JGBdV
Costing
• A 9 million element system with a total system cost of
250M € can spend:
– 1,5 € per LNA per Kelvin improvement (Survey)
– Or 8,5 € for 5 Kelvin improvement, again for Surveys
• Given a bare die costs of:
– 0,5 € for Silicon technologies (only 500 12 inch wafers)
– 2 € for GaAs technologies (2000 6 inch wafers)
• Low cost technologies cannot compromise on noise!
wide band low noise receiver
SKADS Workshop 2007
JGBdV
Technology
• GaAs PsHEMT / mHEMT
FMIN  1 
f
 g m rg  rs 
fT
2
2
 2I C
fT
n 2 fT 
f
FMIN
 1  Noise
 Figure
 Trends
([email protected]
 rBGHz
)(1 Tamb=290K
)
Amplifier
2
2 
 0 fT
V

f

f
T
0
0


n
• CMOS
Noise Temperature
• SiGe BJT
70
• with b0 =100: FMIN~30K
60
50
III/V: GaAs or InP
40
SiGe
30
FMIN  1 
20
• In principle similar to
GaAs
10
0
2000
2002
2004
2006
2008
2010

CMOS 2
f
   1 c
fT

2012
year
wide band low noise receiver
SKADS Workshop 2007
JGBdV
PsHEMT
• 0.2um technology
• OMMIC differential LNA
– 2109
– ASTRON design
wide band low noise receiver
SKADS Workshop 2007
JGBdV
InP
• Differential LNA
• NGST
wide band low noise receiver
SKADS Workshop 2007
JGBdV
mHEMT
• 70nm OMMIC technology
– 250GHz fT
– Differential design
– Optional on-chip biasing
wide band low noise receiver
SKADS Workshop 2007
JGBdV
mHEMT
• 70nm OMMIC technology
– 250GHz fT
– Differential design
– Optional on-chip biasing
wide band low noise receiver
SKADS Workshop 2007
JGBdV
mHEMT
ATNF01_40LNA_05A, Russel Gough
• 70nm OMMIC technology
• Designed for 30-50 GHz band
• 4-stage low-noise amplifier
• Transistors: 6-fingers, 90um gate width
• Bias:
– Vds = 1.0 V
– Id = 13 mA
wide band low noise receiver
SKADS Workshop 2007
JGBdV
ATNF01_40LNA_05A
• 10 circuits were delivered
– sample of 4 was measured
• 1 circuit was unstable (|S11|>1)
• The performance of remaining 3
circuits was similar
• Measured gain is greater than
modelled
• Input and output match is poorer than
expected
wide band low noise receiver
SKADS Workshop 2007
JGBdV
SiGe
• IBM technology
– 8HP (0.13µm) : sub 0.5dB noise figure possible
•
0.25dB for 9HP??
– (relative) high Rn
– Good power match possible
– Limited cooling boosts current gain β:
Weinreb 2005
wide band low noise receiver
SKADS Workshop 2007
JGBdV
wide band low noise receiver
SKADS Workshop 2007
JGBdV
• SKA / LOFAR workshop!
(or focussed session)
vaate@astron
wide band low noise receiver
SKADS Workshop 2007
JGBdV
Conclusion
• SKA specifications for AA within reach it seems but…
– T coupling (<5) (active reflection coefficient)
– T spill-over, ground noise (<5)
– T antenna losses (<5)
• Technology choice will be based on performance
• Good case for III/V, but also CMOS
wide band low noise receiver
SKADS Workshop 2007
JGBdV