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Improvements in Microwave and Sub-mm Frontend Technology for Use up to 900GHz

Radiometer Physics GmbH (RPG), Germany. Improvements in Microwave and Sub-mm Frontend Technology for Use up to 900GHz. Harald Czekala RPG Thomas Rose RPG AchimWalber RPG Hugh Gibson RPG Oleg Cojocari ACST Byron Alderman STFC RAL. RPG Company Profile. Microwave, sub-mm, THz

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Improvements in Microwave and Sub-mm Frontend Technology for Use up to 900GHz

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  1. Radiometer Physics GmbH (RPG), Germany Improvements in Microwave and Sub-mm Frontend Technology for Use up to 900GHz Harald Czekala RPG Thomas Rose RPG AchimWalber RPGHugh Gibson RPG Oleg Cojocari ACST Byron Alderman STFC RAL

  2. RPG Company Profile Microwave, sub-mm, THz Turn-key radiometers, space technology components, design, scientific expertise ■ 4 decades experience ■ 40 employees ■ Radiometers (space) ■ Frontends/Receivers ■ Lab equipment / VNA ■ Components up to THz ■ Design+Manufacturing

  3. Outline • Direct detection (MMIC) for frequencies up to 120 GHz • Auto-calibration receivers up to 200 GHz (noise-injection / Dicke sw.) • Improvements in mixer and multiplier designs through close cooperation with Schottky diode suppliers • Schottky technology from ACST (Germany) • Schottky technology from RAL (UK) • Subharmonic mixers at 424 GHz and 664 GHz • InGaAS mixers with reduction of LO power by 10 dB

  4. Direct Detection • Direct detection systems up to 110 GHz (since 8 years now…) • LNA mostly based on MMIC supply from IAF Freiburg, Germany • At 118 / 150 / 183 GHz and above, sub-harmonic mixers still have better performance (at least with high-quality sub-harmonic mixers) • Waveguide filters with high stability and narrow bandwidth (0.25 %) 55 dB Pre-Amplifier Splitter and Filter Section Boosters and Detectors Video Amps, MUX, 16 Bit ADC Noise Injection Coupler 51- 59 GHz 7 Channel Filterbank Receiver 170 mm Corrugated Feedhorn

  5. Direct Detection Receivers Compared to heterodyne systems: • Improved noise figure • Decreased long term stability (larger 1/f noise with InP MMICs) • Much better RFI protection • Compact (integrated) design • No planar filters, all waveguide Low loss Ortho-Mode Transducer Tsys < 600 K (NF: 4.9) 90 GHz dual-pol (FM)

  6. Direct Detection: MMIC mounting • Mounting of all amplifier types • Experience in micromachining • Bonding and soldering to space standards

  7. Auto-calibration receivers: Noise injection, Dicke Switching Uambient+noise Uambient DetectorVoltage Usignal Usignal Repetition: 5 Hz Duty cycle: 45 % (due to 10 ms switch time) 0.05 0.10 0.15 0.20 Time / s Fast calibration with noise diodes and ambient load(gain and Tsys are calibrated) Ambient load / Dicke switch:Isolatorsdriven by switchedmagnetic field Noise diodes:mounted directlyin a waveguidecoupling section Applied to direct detectionas well as heterodynereceivers

  8. Auto-Calibration Receivers (II) • Noise injection calibration up to 200 GHz • 7.000 K signal at 183 GHz with stable noise diode (15 dB ENR) • Magnetically switched isolators:Dicke switching up to 150 GHz with low insertion loss (≤1.0 dB) • Fast switching with low currents (small thermal effects, 100 mA, 0.5 V) ESA-ATPROP 15 / 90 GHz • Allan Variance Stability: 4.000 s • Less dependent on external calibration targets (LN2)!

  9. Auto-calibration receivers (III): 90+150 GHz system Achieved System Noise Temperatures: (incl. noise injection coupler, Dicke switch, isolator) 90 GHz: 750 K 150 GHz: 1200 K Full internal calibrationIsolation > 30 dB Insertion loss @ 90 GHz: 0.7 dB Insertion loss @ 150 GHz: 1.0 dB Allan Variance up to 4000 s

  10. Auto-calibration receivers (IV): 183 GHz system Heterodyne receiver at 183 GHzwith 6 channel Filterbank • Channel centers in IF: 0.6, 1.5, 2.5, 3.5, 5.0, 7.5 GHz • Noise injection for calibration • Tsys=1200 K for complete radiometer • Tsys=380 to 450 K for mixer • Schottky mixer diodeby ACST (Germany) Dome-C, Antarctica 3.300m asl, -25 to -80 °C Close to South-Pole Similar System on HAMP (HALO Microwave Package) for HALO research aircraft

  11. Schottky Mixer and Multiplier Improvements Anode pillar (contact pad) Air-bridge Membrane- substrate Mesa with anode Cathode pillar (contact pad) Back-side ohmic 25μm 50μm Air-bridges Mesas Membrane- substrate Protection pillars (contact pads) Back-side ohmic RAL Diode • Planar technology • Discrete Schottky devices • Semi-integrated and full integrated structures Two collaborations: • STFC/RAL, UK • ACST, Germany Mandatory improvements for 800 to 1000 GHz circuit mountings: • Reduced Cj0 • Reduced Cstr • Smaller size ESTEC Contract 22032/08/NL/JA: Sub-Millimeter Wave Receiver Front-End (at 664 GHz) ESTEC Contract 21628/08/NL/GLC: Integrated Schottky Structures (at 664 GHz) ACST Diode Quasi-vertical (QVD) single Diode (SD) Anti-parallel (APD) diode

  12. Improved Diodes: Vector Network Analyzer Products 50–75 GHz 60 – 90 GHz 75–110 GHz 90 – 140 GHz 110 – 170 GHz 140–220 GHz 220–325 GHz 325–500 GHz (500 – 750 GHz) OEM Network Analyzer Frequency Extenders for Rohde & Schwarz Courtesy of Rohde & Schwarz

  13. Improved Diodes: Tx/Rx Products Transmit / Receive Systems: 90 GHz 183 GHz 220 GHz 324 GHz 502 GHz 640 GHz 870 GHz For compact ranges (antenna measurement facilities, phase + amplitude) Multipixel Array 220 – 325 GHz

  14. Improved Diodes: RPG sub-harmonic mixers

  15. Receiver technology – 183 GHz example 183 GHz feeds and sub-harmonic mixers for ALMA-WVR • Best 183 GHz receivers available • Built in larger numbers • Noise-injection calibration @183(RPG only manufacturer world wide) • All ALMA water vapor radiometers equipped with RPG mixers and feeds

  16. Improved Diodes: RPG sub-harmonic mixers

  17. Sub-Harmonic Mixer: 424 GHz LO Power: 5 mW Tmix=800 to 1200 K Tsys=1800 K (Feed, SHM, IF Amp, Detection) Conversion= –7 dB

  18. Sub-Harmonic Mixer: 664 GHz LO Power: 3 mW Tmix ≈ 1600 K Conversion: –7.5 to –9.5 dB

  19. Further Schottky Diode Optimization: InGaAs Only at ACST:InGaAs Diode • InGaAs built-in voltage (barrier height) significantly lower than GaAs(0.2eV compared to 0.8eV) • Reduced LO power required for SHM at 183 GHz: 0.34 mW (10 dB less!) 183 GHz InGaAs mixer with 0.2 / 0.25 / 0.34 mW LO-power

  20. Examples: Frontends and sub-systems for Space FIRST/HIFI FIRST/HIFI • Space qualified local oscillators (Herschel / ESA): • 8 local oscillator chains from 480 GHz to 1100 GHz • Other space projects: • EOS (NASA), ODIN (SSA), FIRST/HIFI, • MARFEQ, SAPHIR (CNES), MLS (NASA), FY-3 (China), …

  21. Space Products (II) Space qualified front ends (China, FY-3): 183 GHz (4 channels) water vapour sounder

  22. Space Products (III) • Space qualified front ends (China, FY-3): • 90 GHz dual polarized receiver OMT + LNA + (either Direct Detection or Heterodyne) • 150 GHz dual polarized receiver: OMT + SHM

  23. Conclusion / Summary • Direct detection with superior performance (over heterodyne) up to 120 GHz (until better MMIC LNA technology becomes available) • Auto-calibration receivers up to 200 GHz • Cooperation with Schottky diode manufacturers for improved devices • Development of improved mixers and multipliers up to 900 GHz, leading to: • VNA extenders covering all bands to 500 GHz (and soon even further) • Transmit/Receive systems up to 900 GHz • Excellent sub-harmonic mixers • Outstanding performance at 183 GHz, 424 GHz, 664 GHz Further steps: ■ Substrate Transfer ■ High-Power varactors (driver stages for THz) ■ Film Diode Technology ■ Continuing reduction of capacities and size Results partly supported by: ESTEC Contract 22032/08/NL/JA: Sub-Millimeter Wave Receiver Front-End @ 664 GHz ESTEC Contract 21628/08/NL/GLC: Integrated Schottky Structures @ 664 GHz Thank you!

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