1. 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

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
Microwave Technology and Techniques Workshop ESTEC,

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
Microwave Technology and Techniques Workshop ESTEC,

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 %)
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
GHz
7 Channel
Filterbank Receiver
170 mm
Corrugated
Feedhorn
Microwave Technology and Techniques Workshop ESTEC,

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)
Microwave Technology and Techniques Workshop ESTEC,

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

7. 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,

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: s
Less dependent on external calibration
targets (LN2)!
Microwave Technology and Techniques Workshop ESTEC,

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

10. 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,

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,

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
Microwave Technology and Techniques Workshop ESTEC,

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
Microwave Technology and Techniques Workshop ESTEC,

14. 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
500 K
-5 dB
> 16GHz
6 dBm
WR15
WR8
SHM137
-6 dB
> 20 GHz
4-7 dBm
WR12
WR6.5
SHM150
450 K
> 16 GHz
2 dBm
SHM183
430 K
-4 / -5 dB
4 dBm
WR10
WR5.1
SHM220
> 18 GHz
SHM280
700 K
-7 dB
WR3.4
SHM300
900 K
SHM340
1000 K
-6 / -7 dB
WR2.8
SHM424
1100 K
-7/ -8 dB
7 dBm
WR4.3
WR2.2
SHM664
1600 K
-8 dB
WR1.5
Microwave Technology and Techniques Workshop ESTEC,

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 (RPG only manufacturer world wide)
All ALMA water vapor radiometers equipped with RPG mixers and feeds
Microwave Technology and Techniques Workshop ESTEC,

16. 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
500 K
-5 dB
> 16GHz
6 dBm
WR15
WR8
SHM137
-6 dB
> 20 GHz
4-7 dBm
WR12
WR6.5
SHM150
450 K
> 16 GHz
2 dBm
SHM183
430 K
-4 / -5 dB
4 dBm
WR10
WR5.1
SHM220
> 18 GHz
SHM280
700 K
-7 dB
WR3.4
SHM300
900 K
SHM340
1000 K
-6 / -7 dB
WR2.8
SHM424
1100 K
-7/ -8 dB
7 dBm
WR4.3
WR2.2
SHM664
1600 K
-8 dB
WR1.5
Microwave Technology and Techniques Workshop ESTEC,

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
Microwave Technology and Techniques Workshop ESTEC,

18. 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,

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
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,

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), …
Microwave Technology and Techniques Workshop ESTEC,

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

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
Microwave Technology and Techniques Workshop ESTEC,

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 664 GHz
ESTEC Contract 21628/08/NL/GLC: Integrated Schottky Structures @ 664 GHz
Thank you!
Microwave Technology and Techniques Workshop ESTEC,