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  • 1. W-BAND RADIOMETER SYSTEMWITH SWITCHING FRONT-END FORMULTI-LOAD CALIBRATIONIGARSS 2011, Vancouver, Canada, session TH4.T03.2 July, 28th 2011 E. Weissbrodt, I. Kallfass, A. Hülsmann, A. Tessmann, A. Leuther, H. Massler, O. Ambacher Fraunhofer Institute for Applied Solid-State Physics (IAF) D-79108 Freiburg, Germany© Fraunhofer IAF IGARSS 2011
  • 2. Outline motivation radiometer architecture packaging and modules MMIC technology millimeter-wave circuits multi-load calibration IAF outlook 2© Fraunhofer IAF IGARSS 2011
  • 3. Motivation Compact Internal Calibration external hot-cold calibration microwave black body (absorber) reflectors to cold sky (cosmic background radiation) or liquid nitrogen internal calibration methods noise diodes (ENR) matched (ambient) loads active loads 3© Fraunhofer IAF IGARSS 2011
  • 4. W-Band Direct Detection Radiometer Architecture millimeter wave direct detection radiometer chain SP5T switch LNA LNA BP LNA detector OpAmp OpAmp OpAmp SP5T Video analog switch sub. 50 Ω 20dB 20dB 20dB noise + record noise + 50Ω record DC +0,4V TTL -1V CLK 1kHz switch voltage control discrete modules with Fraunhofer IAF 100nm mHEMT technology 60 dB small-signal gain analog read-out and control electronics for IAF Dicke-operation 4© Fraunhofer IAF IGARSS 2011
  • 5. Packaging Split Block Waveguide Modules IAF in-house CAD-design and milling gold-plated brass split block WR-10 waveguide wedge-bonded 25 μm gold wires 50 μm quartz substrates EM-simulated microstrip- to-waveguide transitions IAF 5© Fraunhofer IAF IGARSS 2011
  • 6. mHEMT Technology High Frequency – Ultra Low Noise parameters 100 nm In content (%) 65 RC (Ωmm) 0.07 RS (Ωmm) 0.23 Rg (Ω/mm) 400 ID,max (mA/mm) 900 VBD (V) 4 Gm,max InGaAs channels with high indium 1300 (mS/mm) content on 4 inch GaAs wafers fT (GHz) 220 metamorphic HEMT technology (mHEMT), 100 nm, 50 nm, 35 nm fmax (GHz) 300 metamorphic buffer layer to adapt lattice constant 6© Fraunhofer IAF IGARSS 2011
  • 7. MMIC Technology Passive Structures microstrip technology 2.7 μm Au air bridge technology grounded coplanar technology 225 pF/mm2 MIM capacitors two metalization layers 50 Ω/□ NiCr resistors 250 nm CVD SiN passivation full-wafer backside process METG GATE SiN SiN MET1 MESA OH MET1 NiCr M SUBSTRATE Au 7© Fraunhofer IAF IGARSS 2011
  • 8. Millimeter-Wave Circuits Low-Noise Amplifier reactively matched cascode mHEMTs gate width 4 × 15 μm chip-size 0.75 × 1.5 mm2 25 5 20 4 gain > 20 dB (75 - 105 GHz) gain NF [dB]gain [dB] 15 3 noise figure 2 dB @ T = 293 K 10 2 (noise temperature 170 K) 5 NF 1 power consumption 48 mW (Vd = 1.6 V, Id = 30 mA) 0 0 80 85 90 95 100 Frequency [GHz] 8 © Fraunhofer IAF IGARSS 2011
  • 9. Millimeter-Wave Circuits Single-Pole-Five-Throw Switch 1-dB bandwidth > 31 GHz Open: S1X = SX1 > -4.3 dB Close: S1X = SX1 < -24 dB SXX < -10 dB 9© Fraunhofer IAF IGARSS 2011
  • 10. Multi-Load Calibration Switching Front-End compact dimensions and lightweight, no mechanics fast switching, moderate insertion loss multiple external reference loads and/or multiple input channels Integrated 50 Ω load, active loads will be integrated in subsequent designs and reduce interface losses 10© Fraunhofer IAF IGARSS 2011
  • 11. Multi-Load Calibration vs. External Calibrationexternal calibration: internal multiload calibration: mature process upcoming technology well known references multiple references possible without antenna is inside the calibration loop additional effort active loads can be monolithically moving parts and mechanical wear integrated in front-end orbital manoeuvers lightweight and fast switching limited speed of calibration reduced calibration time heavy and bulky systems increased front-end losses antenna needs to be calibrated separately temperature monitoring necessary 11© Fraunhofer IAF IGARSS 2011
  • 12. Mechanical Scanning System Cassegrain Antenna commercial antenna tracking system 60cm Cassegrain antenna integrated webcam for optical reference mechanical scan in azimuth and elevation 2.6 rpm max. (azimuth) 15.5°/sec max. (elevation) positioning accuracy ±0.04° 12© Fraunhofer IAF IGARSS 2011
  • 13. Passive Millimeter-Wave Image Compared to Optical Image IAF IAF 13© Fraunhofer IAF IGARSS 2011
  • 14. Outlook packaging of active loads to connect to the switching front-end module example switching front-end with integrated active loads digitalization of read-out electronics for micro-controlled implementation of calibration algorithms IAF 14© Fraunhofer IAF IGARSS 2011
  • 15. Thank You for Your Attentionwe express our gratitude to Michael Schlechtweg for his continuous support Helmut Essen and our colleagues at Fraunhofer FHR for valuable discussions and provision of antenna hardware our colleagues at IAF for their excellent contribution during epitaxial growth and wafer processingthis work was supported by the German Federal Ministry of Defence (BMVg) the Bundeswehr Technical Center for Information Technology and Electronics (WTD81) 15© Fraunhofer IAF IGARSS 2011
  • 16. Backup Slides 16© Fraunhofer IAF IGARSS 2011
  • 17. Backup Slides Highly Integrated Compact Radiometer Module single-chip radiometer MMIC 50 dB small-signal gain SMA, detector video signal integrated diode detector integrated SPDT internal matched load SMB, DC supply 5 V SMB, switch control WR-10 input SMB, switch control IAF internal matched load WR-10 input flange SMA, detector reference signal 17© Fraunhofer IAF IGARSS 2011
  • 18. Backup Slides Participation in ESA Projects 54 GHz Radiometer With Digital Backend 22336/09/NL/EL Cloud Radar Critical Microwave Technology 13521/99/NL/PB LNAs for mmWaves ITT AO/1-5619/08/NL/GLC Calibration Loads for Radiometers 4000101234/10/NL/CLC Direct Detection Radiometers ITT AO/1-6606/10/NL/GLC 18© Fraunhofer IAF IGARSS 2011
  • 19. Backup Slides Hot-Cold Calibration examples of earth observation missions and their calibration methods: Oceansat-1 (MSMR): external blackbody / cold sky Aqua (HSB): external blackbody / cold sky SMOS (MIRAS): internal noise diode / cold sky 19© Fraunhofer IAF IGARSS 2011
  • 20. Backup Slides Status of IAF mHEMT Technology transit frequencies Status: fT = 220 GHz 35 nm mHEMT fT = 375 GHz fT > 500 GHz 100 nm fT = 515 GHz fmax > 900 GHz 50 nm Target: 35 nm ⇒ 20 nm mHEMT fmax > 1.3 THz 20 nm fT = 660 GHz 20© Fraunhofer IAF IGARSS 2011