Improvements in Microwave and Sub-mm Frontend Technology for Use up to 900GHz Radiometer Physics GmbH (RPG), Germany Harald Czekala RPG Thomas RoseRPG AchimWalber RPG Hugh GibsonRPG Oleg CojocariACST Byron AldermanSTFC RAL

Microwave Technology and Techniques Workshop ESTEC, 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, Outline: Receiver and Frontend technology at RPG ■Direct detection (MMIC) for frequencies up to 120 GHz (LNA noise performance superior to heterodyne receivers) ■Auto-calibration receivers up to 200 GHz (noise injection + magnetic Dicke switching) ■At 118 GHz and up: sub-harmonic mixers (planar structures) ■Improvements in mixer and multiplier designs through close cooperation with Schottky diode suppliers ■Results of cooperation with Schottky technology 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, 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 %) Splitter and Filter Section Boosters and Detectors Video Amps, MUX, 16 Bit ADC 55 dB Pre-Amplifier Noise Injection Coupler GHz 7 Channel Filterbank Receiver Corrugated Feedhorn 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 Tsys (with horn, noise-inject., isolator) 20 – 30 GHz280 K (NF: 2.9) 50 – 60 GHz550 K (NF: 4.6) 90 GHz700 K (NF: 5.3)

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

Microwave Technology and Techniques Workshop ESTEC, Auto-Calibration Receivers  Allan Variance Stability: s  Less dependent on external calibration targets (LN2)! 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)

Microwave Technology and Techniques Workshop ESTEC, Achieved System Noise Temperatures: (incl. noise injection coupler, Dicke switch, isolator) 90 GHz: 750 K 150 GHz: 1200 K Allan Variance up to 4000 s Full internal calibration Isolation > 30 dB Insertion 90 GHz: 0.7 dB Insertion 150 GHz: 1.0 dB Auto-calibration receivers GHz systems

Microwave Technology and Techniques Workshop ESTEC, 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) Auto-calibration receivers 183 GHz system Similar System on HAMP (HALO Microwave Package) for HALO research aircraft Dome-C, Antarctica 3.300m asl, -25 to -80 °C Close to South-Pole

Microwave Technology and Techniques Workshop ESTEC, 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 C j0 Reduced C str Smaller size Air-bridge Mesa with anode Anode pillar (contact pad) Cathode pillar (contact pad) Back-side ohmic Membrane- substrate Air-bridges Mesas Protection pillars (contact pads) Back-side ohmic Membrane- substrate 25μm 50μm Quasi-vertical (QVD) single Diode (SD) Anti-parallel (APD) diode RAL Diode ACST Diode

Microwave Technology and Techniques Workshop ESTEC, Vector Network Analyzer Products OEM Network Analyzer Frequency Extenders for Rohde & Schwarz 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 …

Microwave Technology and Techniques Workshop ESTEC, 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)

Microwave Technology and Techniques Workshop ESTEC, RPG sub-harmonic mixers Art.-No. RF Range [GHz] DSB-Noise Temperature Conversion Gain (DSB) IF-Band- width Required LO Power Waveguide LO RF SHM K-5 dB> 16GHz6 dBmWR15WR8 SHM K-6 dB> 20 GHz4-7 dBmWR12WR6.5 SHM K-6 dB> 16 GHz2 dBmWR12WR6.5 SHM K -4 / -5 dB> 16 GHz4 dBmWR10WR5.1 SHM K-6 dB> 18 GHz4-7 dBmWR10WR5.1 SHM K-7 dB> 18 GHz4-7 dBmWR6.5WR3.4 SHM K-7 dB> 18 GHz4-7 dBmWR6.5WR3.4 SHM K-6 / -7 dB> 16 GHz4-7 dBmWR6.5WR2.8 SHM K-7/ -8 dB> 16 GHz7 dBmWR4.3WR2.2 SHM K-8 dB> 16 GHz4-7 dBmWR3.4WR1.5

Microwave Technology and Techniques Workshop ESTEC, Receiver technology – 183 GHz example Best 183 GHz receivers available Built in larger numbers Noise-injection (RPG only manufacturer world wide) All ALMA water vapor radiometers equipped with RPG mixers and feeds 183 GHz feeds and sub-harmonic mixers for ALMA-WVR

Microwave Technology and Techniques Workshop ESTEC, RPG sub-harmonic mixers Art.-No. RF Range [GHz] DSB-Noise Temperature Conversion Gain (DSB) IF-Band- width Required LO Power Waveguide LO RF SHM K-5 dB> 16GHz6 dBmWR15WR8 SHM K-6 dB> 20 GHz4-7 dBmWR12WR6.5 SHM K-6 dB> 16 GHz2 dBmWR12WR6.5 SHM K-4 / -5 dB> 16 GHz4 dBmWR10WR5.1 SHM K-6 dB> 18 GHz4-7 dBmWR10WR5.1 SHM K-7 dB> 18 GHz4-7 dBmWR6.5WR3.4 SHM K-7 dB> 18 GHz4-7 dBmWR6.5WR3.4 SHM K-6 / -7 dB> 16 GHz4-7 dBmWR6.5WR2.8 SHM K -7/ -8 dB> 16 GHz7 dBmWR4.3WR2.2 SHM K -8 dB> 16 GHz4-7 dBmWR3.4WR1.5

Microwave Technology and Techniques Workshop ESTEC, RPG Sub-Harmonic Mixer: 424 GHz Tsys=1800 K Tmix=800 to 1200 K Conversion= –7 dB LO Power: 5 mW

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

Microwave Technology and Techniques Workshop ESTEC, 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 InGaAsGaAs Tmix700 K500 K 430 K Conv. Loss –6.6 dB–5.5 dB –4.2 dB LO Power 0.34 mW3.0 mW 2.2 mW

Microwave Technology and Techniques Workshop ESTEC, Frontends and sub-systems for Space 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, Space Products 2 Space qualified front ends: 183 GHz (4 channels) for sensitive water vapour detection 90 GHz dual polarized receiver 150 GHz dual polarized receiver

Microwave Technology and Techniques Workshop ESTEC, Direct detection with superior performance (over heterodyne) up to 120 GHz (until better MMIC technology becomes available) Auto-calibration schemes pushed to higher frequencies: –Noise injection up to 200 GHz –Magnetically switched isolators for high isolation, low loss (up to 150 GHz) Development of improved sub-harmonic mixer series from 150 to 800 GHz Further steps: Substrate Transfer Film Diode Technology Continuing reduction of capacities and size For further information: Conclusion / Summary