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ASKAP Industry briefing

Russell Gough October 23, 2009


Outline
· Introduction
· ASKAP specifications · Analog System specifications · Design constraints

· ASKAP prototype PAF receiver system
· Design Options · Solution

· Key challenges and future directions
· Mass production and testing of receiver packages · Component cooling · Integrated receivers (`system-on-a-chip')

CSIRO.

ASKAP Industry briefing - October 23, 2009

Slide 2


ASKAP specifications ASKAP Design Goals:
· · · · Hiigh-dynamiic range H gh-dynam c range Wiide fiielld-of-viiew iimagiing W de f e d-of-v ew mag ng 36 36 12 m 12 m 6 km 6 km 30 30 65 m2//Kellviin 65 m2 Ke v n 1..3x105 m4//Kellviin2//deg2 1 3x105 m4 Ke v n2 deg2 63 Kellviin 63 K e v n (eg.. TSYS = 50 K,, = 80%) (eg TSYS = 50 K = 80%) 700 ­ 1800 MHz 700 ­ 1800 MHz 30 deg2 30 deg2 300 MHz 300 MHz 16 k 16 k 188 receiiver channells 188 rece ver channe s
Slide 3

Number of diishes Number of d shes Diish diiameter D sh d ameter Max baselliine Max base ne Resollutiion Reso ut on Sensiitiiviity Sens t v ty Speed Speed TSYS// TSYS Observiing frequency Observ ng frequency Fiielld of Viiew F e d of V ew Processed Bandwiidth Processed Bandw dth Spectrall channells Spectra channe s Focall Pllane Phased Array Foca P ane Phased Array
CSIRO.

ASKAP Industry briefing - October 23, 2009


Analog System specifications
· Phased array receiver size
· Receiver elements ~200 per antenna 1800 300 ­ 724 768 MHz MHz MHz MHz

· Frequencies
· · · · RF band 700 ­ Instantaneous bandwidth Sampled band 424 Sample clock

· Low-noise amplifiers
· amplifier noise temperature · amplifier gain 40 Kelvin 27 dB 72 dB -19 ±1 dBm into 50 Ohms

· System gain
· Nominal total nett gain

· Output power (to digitiser)
· Nominal IF output power

CSIRO.

ASKAP Industry briefing - October 23, 2009

Slide 4


Design constraints

· Relatively long f/D ratio (f/D = 0.5) · PAF receiver weight must be less than 200kg · High attenuation in coax cable from prime focus to pedestal
17dB at 0.7GHz 31dB at 1.8GHz

· Minimise RFI generated · Maximise RFI immunity

CSIRO.

ASKAP Industry briefing - October 23, 2009

Slide 5


Design options
Dual conversion receiver - requires 2 LOs

· Conversion scheme
· Dual conversion (superheterodyne) receiver OR · Direct conversion (I&Q) receiver

· Analog RF (IF) signal transmission

· Over optical fibreDirect conversion (I&Q) receiver - requires 1 LO OR · Over coaxial cable

· Receiver architecture options
· (1) Frequency conversion and sampler at the focus OR · (2) Frequency conversion at the focus and sampler in the pedestal OR · (3) Frequency conversion and sampler in the pedestal

CSIRO.

ASKAP Industry briefing - October 23, 2009

Slide 6


(1) Frequency conversion and sampler at the fo c u s

Focus
LNA

Cable wraps
Sampled IF on optical fibre

Pedestal

RF gain RF filters

Frequency Conversion* *Dual conversion OR Direct conversion I&Q

A/D

CSIRO.

ASKAP Industry briefing - October 23, 2009

Slide 7


(2) Frequency conversion at the focus, sampler in th e p e d e s ta l

Focus
LNA

Cable wraps
IF on copper OR IF on optical fibre

Pedestal

RF gain RF filters

Frequency Conversion* *Dual conversion

A/D

CSIRO.

ASKAP Industry briefing - October 23, 2009

Slide 8


(3) Frequency conversion and sampler in the p e d e s ta l

Focus
LNA

Cable wraps
RF on copper OR RF on optical fibre

Pedestal

RF gain RF filters

Frequency Conversion*

A/D

*Dual conversion OR Direct conversion I&Q

CSIRO.

ASKAP Industry briefing - October 23, 2009

Slide 9


ASKAP Analog System architecture

Focus
LNA

Cable wraps
RF on copper

Pedestal

RF gain RF filters

Frequency Conversion* *Dual conversion

A/D

· Frequency conversion and sampler in the pedestal · Analog RF signal transmission over coaxial cable · Dual conversion (superheterodyne) receiver
CSIRO.

ASKAP Industry briefing - October 23, 2009

Slide 10


ASKAP Analog System architecture with 200 receiver elements

CSIRO.

ASKAP Industry briefing - October 23, 2009

Slide 11


Prime Focus package

CSIRO.

ASKAP Industry briefing - October 23, 2009

Slide 12


Key challenges and future directions
· Mass production and testing of receiver packages
· With ~200 receiver elements per antenna

· Component cooling · Integrated receivers (`system-on-a-chip')

CSIRO.

ASKAP Industry briefing - October 23, 2009

Slide 13


Key challenges and future directions
· Mass production and testing of receiver packages
· With ~200 receiver elements per antenna

· Component cooling
· Low-noise amplifier dissipation: 120 mW · Cryogenic cooling of critical components of receiver electronics (eg. low-noise amplifier significantly improves receiver sensitivity · Cryogenic cooling is especially important at frequencies where the potential improvement in system is greater the s) higher sensitivity

· Cryogenic cooling to 20 Kelvin or 70 Kelvin. · Cooling of the whole receiver package or distributed cooling of individual low-noise amplifiers.
CSIRO.

ASKAP Industry briefing - October 23, 2009

Slide 14


Key challenges and future directions
· Mass production and testing of receiver packages
· With ~200 receiver elements per antenna

· Component cooling
· Low-noise amplifier dissipation: 120 mW Component Radiation load: Cold plate Radiation load: Amplifier Bodies Radiation from epoxied feed throughs 200 off low-noise amplifiers (3V/40mA each) Bias wiring for 200 amplifiers 400 Feed pins from focal plane array Total heat load for receiver with 200 LNAs Heat load (Watts) 6 4 0.4 24 11 4 50 Watts

CSIRO.

ASKAP Industry briefing - October 23, 2009

Slide 15


Component cooling ­ using commercial cryo-coolers
RF feed through plate with SMA hermetic connectors Checker-board FPA Hermetic feed-throughs

200 Amplifiers mounted on cold plate

10 off CryoTel GT coolers
CSIRO.

Vacuum chamber internal supports
Slide 16

ASKAP Industry briefing - October 23, 2009


Component cooling ­ distributed cooling of individual low-noise amplifiers

Electronics board Micro cooler strip gas clamp plates

Gas lines

Micro cooler Removable endplates O-Ring seals

Adjustable support Vacuum Chamber

Vacuum line
CSIRO.

Epoxy sealed hermetic lead through
Slide 17

ASKAP Industry briefing - October 23, 2009


Component cooling ­ with an array of micro-coolers
Vacuum Valve ready for connection to pump

CSIRO.

ASKAP Industry briefing - October 23, 2009

Slide 18


MEMS microcooler

· Size: 30 mm x 2.2 mm x 0.5 mm · Nett cooling power: 10 mW @ 96 K

CSIRO.

ASKAP Industry briefing - October 23, 2009

Slide 19


Key challenges and future directions
· Mass production and testing of receiver packages
· With ~200 receiver elements per antenna

· Component cooling · Integrated receivers (`system-on-a-chip')

CSIRO.

ASKAP Industry briefing - October 23, 2009

Slide 20


Key challenges and future directions
Current receiver architecture

Focus
LNA

Cable wraps
RF on copper

Pedestal

RF gain RF filters

Frequency Conversion* *Dual conversion

A/D

CSIRO.

ASKAP Industry briefing - October 23, 2009

Slide 21


Key challenges and future directions
Preferred receiver architecture

Focus
LNA

Cable wraps
Sampled IF on optical fibre

Pedestal

RF gain RF filters

Frequency Conversion Direct conversion I&Q

A/D

· Frequency conversion and sampler at the focus · Digital signal transmission over optical fibre · Direct conversion (I&Q) receiver
CSIRO.

ASKAP Industry briefing - October 23, 2009

Slide 22


Integrated receivers: System-on-a-chip

CSIRO.

ASKAP Industry briefing - October 23, 2009

Slide 23


Australia Telescope National Facility Russell Gough October 23, 2009 Web: www.atnf.csiro.au

Thank you
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