Improvements in Microwave and Sub-mm Frontend Technology for Use up to 900GHz Radiometer Physics GmbH (RPG), Germany 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 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 Microwave Technology and Techniques Workshop ESTEC, 2010-05-11

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 Microwave Technology and Techniques Workshop ESTEC, 2010-05-11

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 %) Tsys (with horn, noise-inject., isolator) 20 – 30 GHz 280 K (NF: 2.9) 50 – 60 GHz 550 K (NF: 4.6) 90 GHz 700 K (NF: 5.3) 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 Microwave Technology and Techniques Workshop ESTEC, 2010-05-11

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) Microwave Technology and Techniques Workshop ESTEC, 2010-05-11

Direct Detection: MMIC mounting Mounting of all amplifier types Experience in micromachining Bonding and soldering to space standards Microwave Technology and Techniques Workshop ESTEC, 2010-05-11

Auto-calibration receivers: Noise injection, Dicke Switching Fast calibration with noise diodes and ambient load (gain and Tsys are calibrated) Ambient load / Dicke switch: Isolators driven by switched magnetic field Noise diodes: mounted directly in a waveguide coupling section Applied to direct detection as well as heterodyne receivers Usignal Uambient+noise Uambient Repetition: 5 Hz Duty cycle: 45 % (due to 10 ms switch time) DetectorVoltage Time / s 0.10 0.20 0.15 0.05 Microwave Technology and Techniques Workshop ESTEC, 2010-05-11

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)! Microwave Technology and Techniques Workshop ESTEC, 2010-05-11

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 calibration Isolation > 30 dB Insertion loss @ 90 GHz: 0.7 dB Insertion loss @ 150 GHz: 1.0 dB Allan Variance up to 4000 s Microwave Technology and Techniques Workshop ESTEC, 2010-05-11

Auto-calibration receivers (IV): 183 GHz system Heterodyne receiver at 183 GHz with 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 diode by 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 Microwave Technology and Techniques Workshop ESTEC, 2010-05-11

Schottky Mixer and Multiplier Improvements 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) RAL Diode Air-bridge Mesa with anode Anode pillar (contact pad) Cathode pillar Back-side ohmic Membrane- substrate Air-bridges Mesas Protection pillars (contact pads) 25μm 50μm ACST Diode Quasi-vertical (QVD) single Diode (SD) Anti-parallel (APD) diode Microwave Technology and Techniques Workshop ESTEC, 2010-05-11

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 Microwave Technology and Techniques Workshop ESTEC, 2010-05-11

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 Microwave Technology and Techniques Workshop ESTEC, 2010-05-11

Improved Diodes: RPG sub-harmonic mixers Art.-No. RF Range [GHz] DSB-Noise Temperature Conversion Gain (DSB) IF-Band- width Required LO Power Waveguide LO RF SHM118 104-132 500 K -5 dB > 16GHz 6 dBm WR15 WR8 SHM137 110-165 -6 dB > 20 GHz 4-7 dBm WR12 WR6.5 SHM150 134-167 450 K > 16 GHz 2 dBm SHM183 167-200 430 K -4 / -5 dB 4 dBm WR10 WR5.1 SHM220 185-230 > 18 GHz SHM280 265-295 700 K -7 dB WR3.4 SHM300 275-330 900 K SHM340 310-360 1000 K -6 / -7 dB WR2.8 SHM424 400-440 1100 K -7/ -8 dB 7 dBm WR4.3 WR2.2 SHM664 644-680 1600 K -8 dB WR1.5 Microwave Technology and Techniques Workshop ESTEC, 2010-05-11

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 Microwave Technology and Techniques Workshop ESTEC, 2010-05-11

Improved Diodes: RPG sub-harmonic mixers Art.-No. RF Range [GHz] DSB-Noise Temperature Conversion Gain (DSB) IF-Band- width Required LO Power Waveguide LO RF SHM118 104-132 500 K -5 dB > 16GHz 6 dBm WR15 WR8 SHM137 110-165 -6 dB > 20 GHz 4-7 dBm WR12 WR6.5 SHM150 134-167 450 K > 16 GHz 2 dBm SHM183 167-200 430 K -4 / -5 dB 4 dBm WR10 WR5.1 SHM220 185-230 > 18 GHz SHM280 265-295 700 K -7 dB WR3.4 SHM300 275-330 900 K SHM340 310-360 1000 K -6 / -7 dB WR2.8 SHM424 400-440 1100 K -7/ -8 dB 7 dBm WR4.3 WR2.2 SHM664 644-680 1600 K -8 dB WR1.5 Microwave Technology and Techniques Workshop ESTEC, 2010-05-11

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 Microwave Technology and Techniques Workshop ESTEC, 2010-05-11

Sub-Harmonic Mixer: 664 GHz LO Power: 3 mW Tmix ≈ 1600 K Conversion: –7.5 to –9.5 dB Microwave Technology and Techniques Workshop ESTEC, 2010-05-11

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 183 GHz InGaAs GaAs Tmix 700 K 500 K 430 K Conv. Loss –6.6 dB –5.5 dB –4.2 dB LO Power 0.34 mW 3.0 mW 2.2 mW Microwave Technology and Techniques Workshop ESTEC, 2010-05-11

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), … Microwave Technology and Techniques Workshop ESTEC, 2010-05-11

Space Products (II) Space qualified front ends (China, FY-3): 183 GHz (4 channels) water vapour sounder Microwave Technology and Techniques Workshop ESTEC, 2010-05-11

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 Microwave Technology and Techniques Workshop ESTEC, 2010-05-11

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! Microwave Technology and Techniques Workshop ESTEC, 2010-05-11