Receiver TDP Report to US SKA Consortium May

Receiver TDP Report to US SKA Consortium May 22, 2008 Sandy Weinreb, Joe Bardin, Glenn Jones, and Hamdi Mani California Institute of Technology sweinreb@caltech. edu • Work Statement • 2008 Telescope Tests – GAVRT 34 m • 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. 4 GHz Sky Background + atmosphere 4 No improvement here! 4 Spillover & Blockage 15 d. B edge taper + 2. 5% blockage, total 4% at 300 K 12 Mesh skirt for 20 d. B taper, reduce blockage to 2% 7 Feed loss 10 cm of. 085”, 7 K + 5 K feed loss 12 Twin-lead feed terminals 5 LNA to feed loss 10 cm of 0. 141 Cu coax bend to dewar, . 04 d. B at 300 K 3 40 mm twin-lead 2 Vacuum feedthru Glass/Kovar bead, 0. 1 d. B 7 Quartz/gold bead, 0. 04 d. B 3 10 cm or. 141 SS/Be. Cu. 09 d. B at 190 K 4 Air line 2 Coupler at 70 K Werlatone C 7753, 0. 2 d. B 3 or noise lamp coupling 2 Total Above 45 Total Above 25 LNA @ 300 K Commercial 0. 5 to 4 GHz LNA 60 Improved LNA @ 300 K 15 LNA @ 60 K Current LNA 14 Improved 70 K LNA 5 Coax in dewar Total Tsys, 300 KLNA 105 Total Tsys, LNA @ 300 K 40 Total Tsys, 60 K LNA 59 Total Tsys. 60 K LNA 30

Wideband Receivers for Tests on 34 m GAVRT Telescope Goal: Efficiency and Tsys Measurements by Sept 2008 4 to 14 GHz Receiver 0. 5 to 4 GHz Receiver < 35 K Tsys LNA+Feed Quadridge Feed and Long-Life 50 K Cooler

Low-Cost Si. Ge 0. 5 to 4 GHz Cryogenic LNA • 7 K noise at 17 K with $. 44 NXP transistor • With STM transistor input stage noise is 2. 5 K at 17 K, and 7 K at 55 K. Si. Ge transistors in 2 mm 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 Input Twin-Lead Lines Active Balun (Differential) LNA for ATA Output coax

Differential Si. Ge LNA Designed for SKA On IBM 8 HP Si. Ge Bi. CMOS Wafer due July, 2008 Example of 5 x 5 mm multi -project die processed by IBM S 21 Te S 11 S 22 5/01/2008 7

Si. Ge HBT Technology Cross-Section Photo reproduced from: http: //users. ece. gatech. edu/~cressler/

A 0. 5 -20 GHz Quadrature Downconverter This chip has been designed and tested by J. Bardin at Caltech with fabrication in the IBM 8 HP Si. Ge 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 d. B from. 5 to 12 GHz

Publications and Reports S. Weinreb, J. C. Bardin, and H. Mani, “Design of Cryogenic Si. Ge 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 Si. Ge 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 -20 GHz Quadrature Downconverter, ” to be published IEEE Bipolar/Bi. CMOS Circuits and Technology Meeting, BCTM 2008, Monterey, CA, Oct 13 -16, 2008. For seminars and internal reports see http: //radiometer. caltech. edu