© Fraunhofer IAF IGARSS 2011

IGARSS 2011, Vancouver, Canada, session TH4.T03.2 July, 28th 2011

W-BAND RADIOMETER SYSTEM WITH SWITCHING FRONT-END FOR MULTI-LOAD CALIBRATION

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

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IGARSS 2011

Outline

motivation

radiometer architecture

packaging and modules

MMIC technology

millimeter-wave circuits

multi-load calibration

outlook

IAF

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IGARSS 2011

MotivationCompact Internal Calibration

external hot-cold calibrationmicrowave black body (absorber)reflectors to cold sky (cosmic backgroundradiation) or liquid nitrogen

internal calibration methodsnoise diodes (ENR)matched (ambient) loadsactive loads

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IGARSS 2011

W-Band Direct Detection Radiometer Architecture

IAF

LNA LNA LNA

20dB 20dB 20dB

SP5T switchBP detector

Video

OpAmp

TTL+0,4V

-1V

switch voltage control

SP5T

50 Ω

switch analogsub.

OpAmp

CLK1kHz

noise + record

noise + 50Ω record DC

OpAmp

millimeter wave direct detection radiometer chain

discrete modules with Fraunhofer IAF 100nm mHEMT technology60 dB small-signal gainanalog read-out and control electronics for Dicke-operation

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IGARSS 2011

PackagingSplit Block Waveguide Modules

in-house CAD-design and millinggold-plated brass split blockWR-10 waveguide

wedge-bonded 25 μm gold wires50 μm quartz substratesEM-simulated microstrip-to-waveguide transitions

IAF

IAF

© Fraunhofer IAF6

IGARSS 2011

mHEMT TechnologyHigh 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(mS/mm)

1300

fT (GHz) 220

fmax (GHz) 300

InGaAs channels with high indium content on 4 inch GaAs wafersmetamorphic HEMT technology (mHEMT), 100 nm, 50 nm, 35 nmmetamorphic buffer layer to adapt lattice constant

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IGARSS 2011

MMIC TechnologyPassive Structures

SiNNiCrOH

MMESA

GATE

SUBSTRATE

Au

METG

SiN

MET1 MET1

microstrip technologygrounded coplanar technologytwo metalization layers250 nm CVD SiN passivation

2.7 μm Au air bridge technology225 pF/mm2 MIM capacitors50 Ω/ NiCr resistorsfull-wafer backside process

© Fraunhofer IAF8

IGARSS 2011

Millimeter-Wave CircuitsLow-Noise Amplifier

0

1

2

3

4

5

80 85 90 95 1000

5

10

15

20

25

gain

[dB

]

Frequency [GHz]

gain

NF

NF

[dB]

reactively matched

cascode mHEMTs

gate width 4 × 15 μm

chip-size 0.75 × 1.5 mm2

gain > 20 dB (75 - 105 GHz)

noise figure 2 dB @ T = 293 K(noise temperature 170 K)

power consumption 48 mW(Vd = 1.6 V, Id = 30 mA)

© Fraunhofer IAF9

IGARSS 2011

Millimeter-Wave CircuitsSingle-Pole-Five-Throw Switch

1-dB bandwidth > 31 GHz

Open: S1X = SX1 > -4.3 dB

Close: S1X = SX1 < -24 dB

SXX < -10 dB

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IGARSS 2011

Multi-Load CalibrationSwitching 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

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IGARSS 2011

Multi-Load Calibrationvs. External Calibration

external calibration:mature processwell known referencesantenna is inside the calibration loop

moving parts and mechanical wearorbital manoeuverslimited speed of calibrationheavy and bulky systems

internal multiload calibration:upcoming technologymultiple references possible withoutadditional effortactive loads can be monolithicallyintegrated in front-endlightweight and fast switchingreduced calibration time

increased front-end lossesantenna needs to be calibratedseparatelytemperature monitoring necessary

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IGARSS 2011

Mechanical Scanning SystemCassegrain Antenna

commercial antenna tracking system60cm Cassegrain antennaintegrated webcam for optical referencemechanical scan in azimuth and elevation

2.6 rpm max. (azimuth)15.5°/sec max. (elevation)positioning accuracy ±0.04°

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IGARSS 2011

Passive Millimeter-Wave ImageCompared to Optical Image

IAF

IAF

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IGARSS 2011

Outlook

packaging of active loads to connect to

the switching front-end module

switching front-end with integrated

active loads

digitalization of read-out electronics

for micro-controlled implementation

of calibration algorithms

example

IAF

© Fraunhofer IAF15

IGARSS 2011

this work was supported bythe German Federal Ministry of Defence (BMVg)the Bundeswehr Technical Center for Information Technology and Electronics (WTD81)

we express our gratitude toMichael Schlechtweg for his continuous supportHelmut Essen and our colleagues at Fraunhofer FHR for valuablediscussions and provision of antenna hardwareour colleagues at IAF for their excellent contribution during epitaxialgrowth and wafer processing

Thank You for Your Attention

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IGARSS 2011

Backup Slides

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IGARSS 2011

Backup SlidesHighly Integrated Compact Radiometer Module

SMA, detector video signal

SMA, detector reference signal

SMB, switch controlWR-10 input

SMB, switch controlinternal matched load

SMB, DC supply 5 V

WR-10 input flange

single-chip radiometer MMIC50 dB small-signal gainintegrated diode detectorintegrated SPDTinternal matched load

IAF

© Fraunhofer IAF18

IGARSS 2011

Backup SlidesParticipation in ESA Projects

54 GHz Radiometer With Digital Backend22336/09/NL/ELCloud Radar Critical Microwave Technology13521/99/NL/PB

LNAs for mmWaves

ITT AO/1-5619/08/NL/GLCCalibration Loads for Radiometers4000101234/10/NL/CLCDirect Detection RadiometersITT AO/1-6606/10/NL/GLC

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IGARSS 2011

Backup SlidesHot-Cold Calibration

examples of earth observation missions and their calibration methods:Oceansat-1 (MSMR): external blackbody / cold skyAqua (HSB): external blackbody / cold skySMOS (MIRAS): internal noise diode / cold sky

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IGARSS 2011

Backup SlidesStatus of IAF mHEMT Technology

transit frequencies

100 nm

50 nm

35 nm

20 nm

fT = 220 GHz

fT = 515 GHz

fT = 375 GHz

fT = 660 GHz

Status:

35 nm mHEMT

fT > 500 GHz

fmax > 900 GHz

Target:

⇒ 20 nm mHEMT fmax > 1.3 THz