Receiver TDP Report to US SKA Consortium Nov 17, 2008, sweinreb@caltech

1. Receiver TDP Report to US SKA ConsortiumNov 17, 2008, sweinreb@caltech.edu Emphasis in Caltech TDP Meeting the 35K Tsys goal, 0.5-10 GHz, SKA Memo #100 with system manufacturable, maintainable, and affordable. Approach Two feeds, approximately 0.5 to 2 and 2 to 10 GHz 60K cooling with proven, low-maintenance coolers SiGe or HEMT LNA’s IC for LNA output to fiber input to be developed later Status SiGe LNA’s SKA Phase 0 Demonstrator – GAVRT 34m Feed Integration

2. 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. SiGe transistors in 2mm plastic package on printed circuit board

3. Wideband Receivers for Tests on 34m GAVRT Telescope Goal: Efficiency and Tsys Measurements by Sept 2008 4 to 14 GHz Receiver < 35K Tsys LNA+Feed 0.5 to 4 GHz Receiver Quadridge Feed and Long-Life 50K Cooler

4. Photograph of 0.5 to 14 GHz System at Goldstone DSS28, October, 2008 Secondary(shadow) 2-14 GHz Cooled Feed 0.5-4 GHzFeed, Cooled LNA Rotatable Tertiary

5. High Frequency 2 - 14 GHz Feed Upconversion Mixer Downconversion Mixer LNA 0.5 – 14 GHz RF in To ADC via fiber Trcvr (K) 4-waypowerdivider Noise and comb cal 21 – 23 GHz Filter 1 GHz LPF LNA To other down conversion chains 22 – 40 GHz First LO 22 GHzSecond LO Low Frequency 0.5 - 4 GHz Feed Freq (MHz) System Tests of 0.5 to 14 GHz System at GoldstoneDemonstrates SKA 35K Tsys Wideband Feasibility On 34m DSS28, October, 2008

6. 1 to 10 GHz Cooled Receiver Development • Build larger version of current 2 to 14 GHz system on GAVRT 34m telescope • 18” diameter x 22” long vacuum cylinder on order can be used with wideband feeds under development by others. • Cool to 60K with 15W cooler on order • Received new Lindgren 1 to 10 GHz Feed • Model feed-in-cylinder patterns with finite-element EM software • Measure patterns of feed in cylinder and compute efficiency • Goal is a manufacturable system with <35K Tsys

7. SKA Wideband Feeds Need Differential LNA’sCaltech will Integrate other candidate feeds with LNA’s and cryogenics - a crucial step for low Tsys and robustoperation Output coax Input Twin-Lead Lines Active Balun (Differential) LNA for ATA

8. Differential SiGe LNA Designed for SKAOn IBM 8HP SiGe BiCMOS Wafer due Jan, 2009 Example of 5 x 5 mm multi-project die processed by IBM S21 Te S11 S22 5/01/2008 8

9. 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 Chip size 1.5 x 1.7 mm Measured image rejection is 50 dB from .5 to 12 GHz

10. Publications and Reports S. Weinreb, J.C. Bardin, and H. Mani, “Design of Cryogenic SiGe Low-Noise 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

11. 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

12. SKA Tsys Budget – Current and Expected 2010