1. Receiver TDP Report to US SKA Consortium Nov 17, 2008, sweinreb@caltech.edusweinreb@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 0.5 to 4 GHz Receiver Quadridge Feed and Long-Life 50K Cooler 4 to 14 GHz Receiver < 35K Tsys LNA+Feed

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

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

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’s Caltech will Integrate other candidate feeds with LNA’s and cryogenics - a crucial step for low Tsys and robust operation Input Twin-Lead Lines Active Balun (Differential) LNA for ATA Output coax

8. Differential SiGe LNA Designed for SKA On IBM 8HP SiGe BiCMOS Wafer due Jan, 2009 5/01/20088 S21 Te S11 S22 Example of 5 x 5 mm multi-project die processed by IBM

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

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.eduhttp://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. ComponentCurrent Technology 2007 Noise, K, 1.4 GHz Innovation Path 2010 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 Coax in dewar 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 Total Tsys, 300KLNA 105 Total Tsys, LNA @ 300K 40 Total Tsys, 60K LNA 59 Total Tsys. 60K LNA 30 SKA Tsys Budget – Current and Expected 2010