Integrated receivers for mid-band SKASuzy JacksonEngineer, Australia Telescope National Facility

SKADS FP6 Meeting Chateau de Limelette 4-6 November, 2009

Integrated receivers for mid-band SKA

Talk overviewMid band SKA receiver challengesASKAP as a bridge to SKARF-CMOS proof of concept receiverProposed integrated receiver for mid-band SKA

Integrated receivers for mid-band SKA

Mid band PAF SKA (from a receiver viewpoint)Some large numbers:

Collecting area1 km2 Field of View20 deg2Sensitivity7000 m2/KSurvey Speed1x109 m4/K2.deg2Observing frequency~500 2000 MHzProcessed Bandwidth>300 MHz

With dish diameter of 15 m

Number of dishes~2500 Focal Plane Phased Array ~400 elementsPAF data rate~2.5 terabits/s

Total no. receivers required~1 million

Integrated receivers for mid-band SKA

Mid-band SKA receiver design challengesCost20 per receiver is ~ 20 million across the SKASize and weightTotal PAF weight limits of 200 kg (for ASKAP antenna) = 500 g per receiverPower consumptionDictated by weight for example 1 kW per antenna = 2.5 W per receiverManufacturability & maintainabilityMinimise number of partsPerformanceLow TnWide RF and IF bandwidthsHigh dynamic rangeRFI minimisation

Integrated receivers for mid-band SKA

For SKA we want to go from this (ASKAP) A/DFrequencyConversion*FocusPedestalCable wrapsLNARF gain RF filters*Dual conversion RF on copper Frequency conversion and sampler in the pedestalAnalog RF signal transmission over coaxial cableDual conversion (superheterodyne) receiver

Integrated receivers for mid-band SKA

To thisA/DFrequencyConversion*FocusPedestalCable wrapsLNARF gain RF filters*Direct conversion I&Q Sampled IF on optical fibreFrequency conversion and sampler at the focusDigital IF signal transmission over fibre directly to beamformer in antenna base or central siteDirect conversion I/Q receiver

Integrated receivers for mid-band SKA

Proof-of-concept RF-CMOS receiverDeveloped from 2004-20080.18m RF-CMOS300 1700 MHz RF rangeI/Q direct downconversion with 300 MHz (2 x 150 MHz) IF bandwidth only one LO required and half ADC sample rate compared to conventional dual conversion scheme.Dual 6 bit averaging termination flash ADCsNoise cancelling input amplifier

Integrated receivers for mid-band SKA

Proof-of-concept RF-CMOS receiver3.5mm x 2.75mmLNARF FILTERSMIXERSQUADRATURELO GENBASEBANDFILTERSADCS

Integrated receivers for mid-band SKA

Some proof-of-concept receiver resultsRF CMOS performance quite good for mid-band use.Tn ~180K (2dB) mid-band. Useable over 200 MHz 2GHz.Passive RF filters worked well despite low-Q bulk CMOS inductors.Exceptional I/Q amplitude and phase match (0.1dB and 1 degree).Isolation between LO and sample clock signals and RF very good, but some sample clock leakage still evident.5th harmonic of 256 MHz sample clock -78 dBm at RF input.Minor ADC problems.Clock to digital output noise coupling limits operation to 150 Msps.40dB SFDR achieved at 150 Msps.Receiver showed the value of implementing the LNA as a separate circuit.Reduction of LO and sample clock leakage.Prevention of physical LNA heating from high power circuitry dissipation (ADC).Fabrication of LNA in very fast CMOS/GaAs/InP process for lowest Tn.

Integrated receivers for mid-band SKA

Proposed integrated receiverDirect-downconversion I/Q architecture with divide-by-4 LOSingle out of band LO requiredI/Q amplitude and phase match expected to be adequate to ensure 40 dB image suppressionImplementation of whole receiver from LNA output to ADC inputIncluding LO synthesiser and all filtersMinimal external components and costLNA off-chip for minimum Tn and maximum flexibilityOff-chip ADC to reduce development costIncludes high power ADC driversMaximum flexibilityRF and baseband gain adjustableRF filter selection switches (including bypass)Baseband filter selectionPower level monitoring in RF and basebandOn-die temperature monitor

Integrated receivers for mid-band SKA

Integrated receiver block diagram

Integrated receivers for mid-band SKA

Target specification highlights250 MHz to 2500 MHz RF range. Onboard by-passable RF filters 700 MHz HP and 1200/1800 MHz LP.I/Q direct quadrature down conversionselectable instantaneous bandwidth from 150 to 600 MHz.40 dB dynamic range.Due to tight I/Q amplitude and phase matchingOnboard LO synthesiser and ADC driver.Plenty of RF and BB gain adjustment:34 59 dB RF gain range, 5 dB steps.8 20 dB BB gain range, 2 dB steps.Compact 6mm square QFN package.Low power (target ~2-3 W).

Integrated receivers for mid-band SKA

Proposed initial Silicon-on-Sapphire development250 MHz to 2500 MHz RF range.I/Q direct quadrature down conversion with selectable instantaneous bandwidth up to 600 MHz.40 dB dynamic range.Onboard ADC driver.8 20 dB BB gain range, 2 dB steps.

Integrated receivers for mid-band SKA

In contextAllows entire receiver to be housed behind feedLightweight and compactLow powerEasily RFI shieldedLow cost (minimal connectors and cabling, low speed ADCs)RF in, digital fibre out.

Digital fibreOut

Receiver cards

LNAs

PAF elements

Integrated receivers for mid-band SKA

Thank youAustralia Telescope National FacilitySuzy JacksonEngineer RF systems

Phone: 02 9372 4359Email: Suzy.Jackson@csiro.auWeb: www.atnf.csiro.au/askap

Integrated receivers for mid-band SKA