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Receiver TDP Report to US SKA Consortium
May 22, 2008
Sandy Weinreb, Joe Bardin, Glenn Jones, and Hamdi Mani
California Institute of Technology
[email protected]
• Work Statement
• 2008 Telescope Tests – GAVRT 34m
• Noise Temperature Budget
• LNA Status
• Feed Integration
Caltech TDP Work Statement
•
Quad-Ridge Feeds – As one robust candidate for SKA wideband feeds, develop
the quad-ridge feed.
•
0.3-1.7 GHz Receiver – A low cost, very low noise receiver covering this
frequency range will be developed over a 4-year period utilizing either a quad-ridge
feed or other wideband feeds being developed by others.
•
1-11 GHz Receiver - A low cost, very low noise receiver covering this frequency
range will be developed over a 4-year period utilizing a selected feed. The task
includes design, packaging, and testing of integrated circuit LNA’s
•
11-25 GHz Receiver - A low noise receiver covering this high frequency range
will be developed over a 3-year starting in 2009. It is not clear at this time whether
the receiver can be included as part of the 1-11 GHz system or if the SKA antenna
will support higher frequencies.
•
IF/LO Development - Experience with EVLA has shown that a large portion of the
receiver cost is in the wide bandwidth frequency conversion, local oscillator
distribution, optical fiber transducers, and A/D conversion. The goal of this work
element is to drastically reduce the cost of these functions by development of
large scale microwave integrated circuits
SKA Tsys Budget – Current and Expected 2010
2007
2010
Component
Current Technology
Noise, K,
1.4 GHz
Innovation Path
Noise, K,
1.4GHz
Sky
Background + atmosphere
4
No improvement here!
4
Spillover &
Blockage
15 dB edge taper + 2.5%
blockage, total 4% at 300K
12
Mesh skirt for 20 dB taper,
reduce blockage to 2%
7
Feed loss
10cm of .085”, 7K + 5K feed
loss
12
Twin-lead feed terminals
5
LNA to feed loss
10cm of 0.141 Cu coax bend
to dewar, .04 dB at 300K
3
40mm twin-lead
2
Vacuum feedthru
Glass/Kovar bead, 0.1 dB
7
Quartz/gold bead, 0.04 dB
3
10cm or .141 SS/BeCu
.09 dB at 190K
4
Air line
2
Coupler at 70K
Werlatone C7753, 0.2 dB
3
or noise lamp coupling
2
Total
Total Above
45
Total Above
25
LNA @ 300K
Commercial 0.5 to 4 GHz LNA
60
Improved LNA @ 300K
15
LNA @ 60K
Current LNA
14
Improved 70K LNA
5
Coax in dewar
Total Tsys, 300KLNA
105
Total Tsys, LNA @ 300K
40
Total Tsys, 60K LNA
59
Total Tsys. 60K LNA
30
Wideband Receivers for Tests on 34m GAVRT Telescope
Goal: Efficiency and Tsys Measurements by Sept 2008
4 to 14 GHz Receiver
0.5 to 4 GHz Receiver
< 35K Tsys LNA+Feed
Quadridge Feed and
Long-Life 50K Cooler
Low-Cost SiGe 0.5 to 4 GHz Cryogenic LNA
• 7K noise at 17K with $.44 NXP transistor
• With STM transistor input stage noise is
2.5K at 17K, and 7K at 55K.
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
40
35
30
25
20
15
Noise, 1.7V, 10mA
10
Gain, 1.7V, 10mA
5
Gain, dB
Noise, K
NXP BFU 725 2 stage LNA @17K
April 15, 2008
0
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
GHz
SiGe transistors in
2mm plastic package
on printed circuit board
SKA Wideband Feeds Need Differential LNA’s
Caltech will Integrate other candidate feeds with LNA’s and cryogenics
- a crucial step for low Tsys and robust operation
Output coax
Input Twin-Lead Lines
Active Balun (Differential) LNA for ATA
Differential SiGe LNA Designed for SKA
On IBM 8HP SiGe BiCMOS Wafer due July, 2008
Example of 5 x 5 mm
multi-project die
processed by IBM
S21
Te
S11
S22
5/01/2008
7
SiGe HBT Technology Cross-Section
Photo reproduced from: http://users.ece.gatech.edu/~cressler/
A 0.5-20GHz Quadrature Downconverter
This chip has been designed and tested by J. Bardin at Caltech with
fabrication in the IBM 8HP SiGe process. It provides highly accurate
quadrature mixers over an unusually large bandwidth
A
RF
D
I
LPF
LNA
LO
Q
DSP
A
D
LO
Chip size 1.5 x 1.7 mm
Measured image
rejection is 50 dB
from .5 to 12 GHz
Downconverter
LPF
Publications and Reports
S. Weinreb, J.C. Bardin, and H. Mani, “Design of Cryogenic SiGe LowNoise Amplifiers,” IEEE Transactions on Microwave Theory and
Techniques, Vol. 55, pp.2306-2311, Nov. 2007.
J.C. Bardin and S. Weinreb, “Experimental Modeling and Noise of
SiGe HBTs,” to be published Proc. IEEE International Microwave
Symposium, IMS, Atlanta, GA, June 16-19, 2008.
J.C. Bardin and S. Weinreb, “A 0.5-20GHz Quadrature
Downconverter,” to be published IEEE Bipolar/BiCMOS Circuits and
Technology Meeting, BCTM2008, Monterey, CA, Oct 13-16, 2008.
For seminars and internal reports see http://radiometer.caltech.edu