Future Arrays for Radio Astronomy and Space Communications

Sander Weinreb

Presentation to KNI/MDL Seminar, Aug 3, 2009

• Square-Km Array• Phased-Array Feeds• Large format focal plane imaging• IC development at Caltech

SKA Reference Design ConceptTasks at Caltech, 2008-2011, are the development of wideband LNA’s

and the integration with wideband feeds.

Major Science Objectives of SKA from 2009 Decadal Review

Square-Km Array Summary

• Aperture synthesis radio telescope with 1 km2 of effective collecting area by 2020

• 50x sensitivity, 10 000x survey speed of existing arrays • Frequency range 0.1 - 25 GHz; 0.1 – 3 GHz in first phase• Large bandwidths (4 GHz), large fields-of-view (50 deg2)• International funding: ~ € 1.5 billion; 17- country consortium• 2 short-listed sites; final selection ~ 2011; W. Australia, S. Africa• Hot technology topics

– Phased-array feeds for wide field of view– Decade bandwidth feeds and LNA’s to reduce receiver cost– RFI mitigation– Digital transmission and processing of GHz bandwidth signals– Replication cost of millions of 100-500 MHz receivers and tens of

thousands of 0.5 to 25 GHz receivers

www.skatelescope.org

The NASA/JPL Deep Space Network (DSN) Could Share the SKA with Radio Astronomy and Greatly Expand the Data Rate from Distant

Spacecraft or Reduce the Size of a Spacecraft for a Given Data Rate.

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Distance, A.U.

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Current DSN 70m @ X band

MARS JUPITER

400 x 12mArray, Ka

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SKASKA--high high ConstructConstruct

26 February 2009

Pathfinder implementation

SKASKA--mid+lowmid+lowCompleteComplete

Phase 1 Phase 1 funding funding requestrequest

System design System design SKASKA--hihi

Pathfinder operations

Phase 1 complete

Concept design for Concept design for SKASKA--highhigh

Early Science SKA mid+low SKA Ops

Phase 2 funding request

Phase 1 Construction

US TDP

Site Selection

Concept Design System Design Full SKA mid + low Full SKA mid + low

construction and construction and commissioningcommissioning

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SKA Program Components and Time Line• SKA program comprises Low (0.1 to 0.5 GHz stationary arrays), Mid (0.3 to 10 GHz 12m reflectors) , and High (1 to 50 GHz).

• Low and mid to be co-located in S. Africa or W. Australia

• Pathfinder (1%) instruments are ATA, LOFAR, ASKAP, and MeerKat

Australia SKA Pathfinder - ASKAP

• Well funded (~$100M US) instrument located at potential SKA site in western Australia. Under construction for completion by 2012

• 36 x 12m antennas on order from China with first antenna due. Antenna has 3rd rotation axis to test dynamic range limitations due to beam rotation.

• Phased-array feed with ~100 dual-polarized elements giving ~30 beams from 0.7 to 1.8 GHz.

Summary of Wideband FeedsFrom Bradley and Gawande, URSI Meeting, Boulder, Jan 2009

Phased-Array Feeds Increase FOV of Radio Telescopes

• At right, crossed-dipole feeds used for tests on 20m telescope at NRAO Green Bank

• Below, beam former outputs for PAF tested at 25m telescope at Westerbork. Beamwidth is ~1o so a 36 beam area field is realized with < 50% loss. Beams that are arbitrarily close can be formed so ~170 beams could be formed with crossover at 1 dB points.

Mapping speed and survey speed can be increased but signal processing costs are substantial and limit bandwidth.

Caltech EE Radio Astronomy Projects

• Wideband cryogenic InP MMIC LNA’s – Over 200 delivered

• Development of very low noise SiGe HBT LNA’s

• MMIC receivers (IF LNA’s and downconverters) for multi-pixel mm-wave and sub-mm arrays

Supercam – U. of Arizona, 64 x 345 GHz receiver

STO – Stratospheric THz Observatory

• MMIC receivers (RF LNA’s and downconverters) for large arraysAllen Telescope Array – Completed 0.5-11 GHz differential-input

cryogenic LNA development in 2005.

SKA – Four years of development starting 2008

• Wideband receivers for educational 34m radio telescope - GAVRT

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6-18GHz LNA #40A03 at 12KMMIC WBA618 R7C1M0 CRYO10-4292-014, Bias: Vd=0.65V, Id=16mA

, Vg1=1.9V , Vg2=1.9VDate : NOV-11-2005

4-12GHz LNA #82D at 12K MMIC: WBA13, CIT1 4254-065 , R8C2

Bias: Vd=1.2V, Id=20mA, Vg1=2.33V, Vg2=2.33V

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4 to 14 GHz, Tn < 8K

6 to 20 GHz, Tn < 12K

11 to 34 GHz, Tn < 20K

Over 200 LNA’s supplied to other research centers

Caltech-Developed Cryogenic LNA’s

Devices from several manufacturers have been measured attemperatures from 300K to 15K as part of the Ph.D. thesis of JoeBardin. A key parameter for noise at < 5 GHz and is the current gain at 15K shown below.

SiGe Cryogenic Low Noise Amplifier Work at Caltech

Minimum Cascaded Noise Temperature vs Frequency and Temperature for 7

Types of SiGe Transistors• Based upon measured S parameter and DC data vs temperature and shot noise model of noise.• From Silicon-Germanium HeterojunctionBipolar Transistors For Extremely Low-Noise Applications, Ph.D. thesis, Caltech, June, 2009, http://resolver.caltech.edu/CaltechETD:etd-06092009-113849

SiGe IC Cross-SectionMany interconnect layers enable complex circuits

Photo reproduced from: http://users.ece.gatech.edu/~cressler/

Substrate

M1, copper, t=0.29umM2, copper, t=0.32umM3, copper, t=0.32umM4, copper, t=0.32umMQ, copper, t=0.55um

LY, aluminum, t=1.25umAM, aluminum, t=4um

4um4um0.65um0.35um0.35um0.35um0.45um

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Current State-of-the-Art, 64 pixel, Millimeter Wave Camera

U. of Arizona, Supercam Project

Caltech 4-12 GHz LNA’s for Integration with 345 GHz SIS Mixers

LNA with cover onInput circuit including SIS bias, MMIC

LNA chip, output line, and, at top, bias filter network

Collaboration with U. of Arizona to Develop 64 Pixel Camera

Packaging Progression

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Multi-Function Chip

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Multi-Pixel Array Wafer

Wafer Scale Integration ofSIS/LNA/Photonic 300 GHz Spectrometer Array

(from July 21, 2008 KISS Imaging Workshop)

1) Hot via interconnections2) Needs feasibility study leading to 5 year plan

3) Alternative to photonics is miniature flexible printed-circuit ribbons

Superconductor - Junctions and antennaSemiconductor IF LNA's

Photonic - lasers

Fiber Bundle

100 x 100 pixels in 5 x 5 cm

Information About 3-D Packaging• See http://www.3d-ic.org/ for news and conferences

• See www.ziptronix.com for video of wafer bonding

• Note presentation by P. Chang-Chien, NGST, at July 21, 2008 KISS workshop

• Chisel open your memory stick to see stacked memory chips!

Spin-On’sTechnology development costs money.

Radio astronomy does not have the funding to make fundamental changes in technology and thus relies on developments funded for applications. However a shift has occurred:

1957-2007 Defense systems, satellite communications

2007-2057 Wireless devices, games, internet service

A 3-D Packaging Commercial Spin-On!

A tire-pressure sensor developed by Infineon and the Fraunhofer Institute Munich is shown below. It integrates a pressure sensor (but imagine a millimeter wave feed horn!), an RF transceiver, and a microcontroller by bump bonds and stacking.

• The Lewis Center for Educational Research (LCER) operates the Goldstone-Apple Valley 34m Radio Telescope, GAVRT, for use in K-12 science education.

• Science teachers are trained by LCER and then use the GAVRT telescope with their students through the Internet

• Important program principle is professional-quality instruments for scientists to interact with the educators and classrooms to generate useful science data.

• Successful ongoing programs are the monitoring of the time-varying radio emissions of Jupiter and the measurements of quasar scintillations.

• GAVRT was founded by the triumvirate of a kindergarten teacher (Rick Piercy), a radio astronomer (Mike Klein), and a member of the US Congress (Jerry Lewis).

• DOD and NASA have appropriated $3.2M for renovation of a second 34m telescope, DSS28, and development of a state-of-the-art radiometer system.

• Caltech has been contracted to develop a 0.5 to 14 GHz radiometer system.

GAVRT, a 34m Radio Telescope for

Outreach and Science