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Technology Perspective and results with mHEMTs. Jan Geralt Bij de Vaate ASTRON. Specification R Schillizi et. al. Sept. ‘07. T instrument = 40K (excluding sky noise), goal 30K BW 70MHz – 1.0 GHz (two systems) Survey speed ~1/T 2 Sensitivity ~1/T. Costing.
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Technology Perspective and results with mHEMTs Jan Geralt Bij de Vaate ASTRON
SpecificationR Schillizi et. al. Sept. ‘07 • Tinstrument= 40K (excluding sky noise), goal 30K • BW 70MHz – 1.0 GHz (two systems) • Survey speed ~1/T2 • Sensitivity ~1/T SKADS Workshop 2007
Costing • A 9 million element system with a total system cost of 250M € can spend: • 1,5 € per LNA per Kelvin improvement (Survey) • Or 8,5 € for 5 Kelvin improvement, again for Surveys • Given a bare die costs of: • 0,5 € for Silicon technologies (only 500 12 inch wafers) • 2 € for GaAs technologies (2000 6 inch wafers) • Low cost technologies cannot compromise on noise! SKADS Workshop 2007
Technology • GaAs PsHEMT / mHEMT • SiGe BJT • with b0 =100: FMIN~30K • CMOS • In principle similar to GaAs SKADS Workshop 2007
PsHEMT • 0.2um technology • OMMIC differential LNA • 2109 • ASTRON design SKADS Workshop 2007
InP • Differential LNA • NGST SKADS Workshop 2007
mHEMT • 70nm OMMIC technology • 250GHz fT • Differential design • Optional on-chip biasing SKADS Workshop 2007
mHEMT • 70nm OMMIC technology • 250GHz fT • Differential design • Optional on-chip biasing SKADS Workshop 2007
mHEMTATNF01_40LNA_05A, Russel Gough • 70nm OMMIC technology • Designed for 30-50 GHz band • 4-stage low-noise amplifier • Transistors: 6-fingers, 90um gate width • Bias: • Vds = 1.0 V • Id = 13 mA SKADS Workshop 2007
ATNF01_40LNA_05A • 10 circuits were delivered • sample of 4 was measured • 1 circuit was unstable (|S11|>1) • The performance of remaining 3 circuits was similar • Measured gain is greater than modelled • Input and output match is poorer than expected SKADS Workshop 2007
SiGe • IBM technology • 8HP (0.13µm) : sub 0.5dB noise figure possible • 0.25dB for 9HP?? • (relative) high Rn • Good power match possible • Limited cooling boosts current gain β: Weinreb 2005 SKADS Workshop 2007
SKA / LOFAR workshop!(or focussed session) vaate@astron SKADS Workshop 2007
Conclusion • SKA specifications for AA within reach it seems but… • T coupling (<5) (active reflection coefficient) • T spill-over, ground noise (<5) • T antenna losses (<5) • Technology choice will be based on performance • Good case for III/V, but also CMOS SKADS Workshop 2007