Receiver TDP Report to US SKA Consortium Nov 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

NXP BFU 725 2 stage LNA @17K April 15, 2008

0123456789

10111213141516

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

GHz

No

ise

, K

0

5

10

15

20

25

30

35

40

Ga

in, d

BNoise, 1.7V, 10mA

Gain, 1.7V, 10mA

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

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

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

Trcvr (K)

Freq (MHz)

System Tests of 0.5 to 14 GHz System at GoldstoneDemonstrates SKA 35K Tsys Wideband Feasibility

On 34m DSS28, October, 2008

LNA

4-waypowerdivider

Noise andcomb 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 GHzSecond LO

21 – 23 GHz Filter

Upconversion Mixer

Downconversion Mixer

To ADC via fiber

1 GHz LPF

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

SKA Wideband Feeds Need Differential LNA’sCaltech 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 SiGe LNA Designed for SKAOn IBM 8HP SiGe BiCMOS Wafer due Jan, 2009

5/01/2008 8

S21

Te

S11

S22

Example of 5 x 5 mm multi-project die processed by IBM

AD

AD

LO

RF I

Q

LNA

Downconverter

LPF

LPF

DSP

LO

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

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

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

Component Current Technology2007

Noise, K, 1.4 GHz

Innovation Path2010

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 105Total Tsys, LNA @

300K 40

Total Tsys, 60K LNA 59 Total Tsys. 60K LNA 30

SKA Tsys Budget – Current and Expected 2010