-
Christian Doppler Laboratory for Design Methodology of Signal Processing Algorithmswww.nt.tuwien.ac.at/cdlab
Vienna University of Technologywww.tuwien.ac.at
Institute of Communications andRadio-Frequency EngineeringGußhausstrasse 25/389Vienna, 1040Austriawww.nt.tuwien.ac.at
Robert Langwieser,Michael Fischer andProf. Dr. Arpad L. Scholtz
EEEfCOM 2008, Ulm
RFID Reader Frontends for a Dual-Frequency (13 MHz and 868 MHz)
Rapid Prototyping Environment
-
2Christian Doppler Laboratory for
Design Methodology of Signal Processing Algorithms
Outline
• Reader – Tag Communication• Analog Frontends for Rapid
Prototyping Environments• HF-Frontend• UHF-Frontend
-
3Christian Doppler Laboratory for
Design Methodology of Signal Processing Algorithms
Reader – Tag Communication
• Tag is powered by the reader • Energy transfer from reader to tag during the
entire communication• Energy transfer happens at the carrier
frequency of the data signal• Cross talk from transmitter to receiver at the
reader
RFID Reader
Passive Tag
Energy
DataData
-
4Christian Doppler Laboratory for
Design Methodology of Signal Processing Algorithms
Analog Frontends for a Rapid Prototyping Environment
• As much functionality as possible should be realized by the digital baseband
• Frequency conversion, filtering and amplification are the tasks of the RF-frontend
-
5Christian Doppler Laboratory for
Design Methodology of Signal Processing Algorithms
HF-Frontend: Requirements
• Frequency: 13.56MHz• Communication range: a few centimeters • Inductive coupling between reader and tag • Load modulation• HF-power of 1 W• Interface with the DSP-hardware
• frequency: 13.56MHz• power levels: determined by ADCs and DACs
• Carrier to sideband ratio improvement
-
6Christian Doppler Laboratory for
Design Methodology of Signal Processing Algorithms
HF-Frontend:Carrier Suppression Principle
-
7Christian Doppler Laboratory for
Design Methodology of Signal Processing Algorithms
HF-Frontend with Tag-Emulator
-
8Christian Doppler Laboratory for
Design Methodology of Signal Processing Algorithms
HF-Frontend: Verification
• Laboratory setup with tag-emulator• Optimal tuning• Modulation signal enhanced by 34 dB
Coil Voltage
Output Voltage
-
9Christian Doppler Laboratory for
Design Methodology of Signal Processing Algorithms
Measurement with Commercial Tag
Transmit coil voltage
Carrier-suppressed output voltage of the HF-Frontend
Distance between tag and transmit coil d = 24 mmMagnetic field at tag position (without Tag) H = 2.4 A/m
-
10Christian Doppler Laboratory for
Design Methodology of Signal Processing Algorithms
UHF-Frontend
• Requirements• Rx/Tx crosstalk
• Antenna configurations• Active Rx/Tx decoupling
• Frontend concept• Verification measurement
-
11Christian Doppler Laboratory for
Design Methodology of Signal Processing Algorithms
Requirements
• Frequency: 865MHz - 868MHz• Communication range: up to 10m• 2 Watt linear output power• Interface with the DSP-hardware
• frequency: 867MHz not directly possiblefrequency conversion necessary
• power level: determined by ADCs and DACs
• Carrier to sideband ratio improvement (carrier suppression)
-
12Christian Doppler Laboratory for
Design Methodology of Signal Processing Algorithms
Separate Rx/Tx Antenna
Rx/Tx isolation: 30 to 40 dB
two antennas
Rx/Tx isolation depends on: -antenna spacing -antenna radiation pattern
cou
pli
ng
-
13Christian Doppler Laboratory for
Design Methodology of Signal Processing Algorithms
Single Rx/Tx Antenna
Rx/Tx isolation: 20 to 30 dB
single antenna
Rx/Tx isolation depends on:-circulator -return loss of antenna
circulator insertion loss: 0.4 – 1 dB
-
14Christian Doppler Laboratory for
Design Methodology of Signal Processing Algorithms
Active Rx/Tx Decoupling
coupling 2
0dB
+13dBm-27dBm
S21S21
S21
S21
Tx
Rx
(+33dBm)
I-CTRL
Q-CTRL
Coupler
Coupler
Vector Modulator
Amp.
-
15Christian Doppler Laboratory for
Design Methodology of Signal Processing Algorithms
UHF Reader Frontend
-
16Christian Doppler Laboratory for
Design Methodology of Signal Processing Algorithms
UHF Transmitter
Tx In13.56 MHz
LO1 In153 MHz
LO2 In1006 MHz
Ext. PA Out868 MHz
To CCU868 MHz
Power Supply,Control Lines
Tx Ant.868 MHz
Ext. PA In868 MHz
To CCU868 MHz
-
17Christian Doppler Laboratory for
Design Methodology of Signal Processing Algorithms
Measurement Setup
4-W
ay
Splitt
er
Transmitter
4-
Way
Splitt
er
Receiver
LeCroy 204Xi
TunerCarrierComp.
Demod. OUT
Rx OUT (13.56MHz)
R&S SMU200A
IQ
tag
Tx IN (13.56MHz)
R&S SMY01
HP8642B
LO1, -5 dBm
LO1, -5 dBm
LO2, 0 dBm
LO2, 0 dBm
CC OUT
CC IN
Tx OUT866.5 MHz
Rx IN866.5 MHz
LO1
LO2 ZMSC-4-3 ZB4PD1-2000
Mini-Cir. Mini-Cir.
Mini-Cir.
Raditek
RC-860-900M
ZHL-2-12
power meter
Agilent E4416A
Trigger
SMA4242-10
-10 dB
153.56 MHz
1005 MHz – 1008MHz
3 m Cable
d
-20 dB
-
18Christian Doppler Laboratory for
Design Methodology of Signal Processing Algorithms
Scenario: Corridor 5th Floor
Power amplifier: Pout = 33.4 dBm
Losses (cable, coupler..): 2.75 dB
Antenna gain: ~5 dBi (~ 2.85 dBd)
Transmit power: ~ 33 dBm ERP
-
19Christian Doppler Laboratory for
Design Methodology of Signal Processing Algorithms
Received Tag Answer
Screenshot at maximum communication range of ~11m
-
20Christian Doppler Laboratory for
Design Methodology of Signal Processing Algorithms
Summary
• Frontends for Rapid Prototyping
• Current implementations for RFID
• HF-Frontend• Rx/Tx decoupling (34 dB carrier suppression achieved)
• Measurements
• UHF-Frontend• Rx/Tx decoupling (antenna configuration, vector modulator)
• Concept and verification(~11m comunication distance achieved)
-
21Christian Doppler Laboratory for
Design Methodology of Signal Processing Algorithms
Thank you!
OutlineReader – Tag CommunicationAnalog Frontends for a Rapid Prototyping EnvironmentHF-Frontend: RequirementsHF-Frontend:�Carrier Suppression PrincipleHF-Frontend with �Tag-EmulatorHF-Frontend: VerificationMeasurement with Commercial TagUHF-FrontendRequirementsSeparate Rx/Tx AntennaSingle Rx/Tx Antenna Active Rx/Tx DecouplingUHF Reader FrontendMeasurement SetupScenario: Corridor 5th FloorReceived Tag AnswerSummary
/ColorImageDict > /JPEG2000ColorACSImageDict > /JPEG2000ColorImageDict > /AntiAliasGrayImages false /CropGrayImages true /GrayImageMinResolution 300 /GrayImageMinResolutionPolicy /OK /DownsampleGrayImages true /GrayImageDownsampleType /Bicubic /GrayImageResolution 300 /GrayImageDepth -1 /GrayImageMinDownsampleDepth 2 /GrayImageDownsampleThreshold 1.50000 /EncodeGrayImages true /GrayImageFilter /DCTEncode /AutoFilterGrayImages true /GrayImageAutoFilterStrategy /JPEG /GrayACSImageDict > /GrayImageDict > /JPEG2000GrayACSImageDict > /JPEG2000GrayImageDict > /AntiAliasMonoImages false /CropMonoImages true /MonoImageMinResolution 1200 /MonoImageMinResolutionPolicy /OK /DownsampleMonoImages true /MonoImageDownsampleType /Bicubic /MonoImageResolution 1200 /MonoImageDepth -1 /MonoImageDownsampleThreshold 1.50000 /EncodeMonoImages true /MonoImageFilter /CCITTFaxEncode /MonoImageDict > /AllowPSXObjects false /CheckCompliance [ /None ] /PDFX1aCheck false /PDFX3Check false /PDFXCompliantPDFOnly false /PDFXNoTrimBoxError true /PDFXTrimBoxToMediaBoxOffset [ 0.00000 0.00000 0.00000 0.00000 ] /PDFXSetBleedBoxToMediaBox true /PDFXBleedBoxToTrimBoxOffset [ 0.00000 0.00000 0.00000 0.00000 ] /PDFXOutputIntentProfile () /PDFXOutputConditionIdentifier () /PDFXOutputCondition () /PDFXRegistryName () /PDFXTrapped /False
/Description > /Namespace [ (Adobe) (Common) (1.0) ] /OtherNamespaces [ > /FormElements false /GenerateStructure true /IncludeBookmarks false /IncludeHyperlinks false /IncludeInteractive false /IncludeLayers false /IncludeProfiles true /MultimediaHandling /UseObjectSettings /Namespace [ (Adobe) (CreativeSuite) (2.0) ] /PDFXOutputIntentProfileSelector /NA /PreserveEditing true /UntaggedCMYKHandling /LeaveUntagged /UntaggedRGBHandling /LeaveUntagged /UseDocumentBleed false >> ]>> setdistillerparams> setpagedevice