9 November 2009 3º Congresso URSI Portugal
A new 5 GHz Receiver for a Galactic
Experiment
Miguel BerganoGRIT – Aveiro
www.av.it.pt/gem
FCT Grants• POCTI/CTE-AST/57209/2004• PTDC/CTE-AST/65925/2006
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Overview
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Unveil the Sky to CMBR;
Applicable to a Galactic Experiment;
High sensitivity radiometer;
Superheterodyne Receiver with Double Down Conversion – Zero IF;
IF chain developed and tested;
Full Digital Back-end;
Stokes Parameters Calculation.
What is CMBR?• Cosmic Microwave Background Radiation
• Best “Big-Bang” relic (Fossil);
• First Sky map: 1992 by COBE satellite COBE (PI G. Smoot,
was awarded the Physics Nobel Prize in 2006 for this discovery)
• CMBR fluctuations (anisotropies) allow to determine the geometry, age of the Universe.
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GEM – Galactic Emission Mapping
• Survey of Syncrotron Polarization@ 5 GHz
• North/South Hemisphere (Portugal and Brasil)
• 80% sky coverage
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Radiometer?
High sensitivity, well calibrated microwave receiver;
Detect and measure celestial sources;
Radiómetro
TA
KJK
WattsKBGTP A
23-101,38BoltzmanndeConstante
,
∫X2
TN
TAVout
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Radiometer Types Amplification:
• Direct;
• Superheterodyne
Accuracy:• Dicke Radiometer
• Noise Injection Radiometer
• Total Power Radiometer
B
TTT NA2
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9 November 2009 3º Congresso URSI Portugal
Superheterodyne Receiver
(Base-band Complex Correlator)
Novel approach to digital correlators!
The radiometer/polarimeter gain budget:
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Antenna
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Receiver
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NFTOTAL= 6,1KGainTOTAL= 104 dB9
Receiver Requirements
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• System Temperature about ~ 20K
• Sensitivity ~ 2mKs-1/2
• Frequency 5GHz with 200MHz Bandwidth
• Gain ~ 100dB
• Suitable for Stokes Parameters Calculation
• LNA Cryocooled PHEMT Amplifiers
LNA Characteristics
GaAs HEMT Low Noise Transistors
Noise Figure between 0,1 and 0,3 dB
Total Gain approximately 22 dB
Noise and S-parameters Simulation in ADS
Substrate to be used: RT5880
CompanyNF
(dB)
GAIN
(dB)
@Freq.
(GHz)
MGF4953 Mitsubishi 0,40 13,5 12
MGF4941 Mitsubishi 0,35 13,5 12
MGF4419 Mitsubishi 0,50 12 12
ATF-36077 Agilent 0,5 12 12
MGF4931 Mitsubishi 0,60 11,5 12
NE3511S02 NEC 0,30 13,5 12
FHX13X Fujitsu 0,45 13 12
No longer manufactured
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SIMULATIONS S and Noise Parameters provided by the
manufacturer Adjustments of components to obtain the
desired result Challenge is to create good matching networks,
that will provide the lowest NF; Obtain a large frequency band of low NF.
DeviceNF
(dB @ 5GHz)
GAIN
(dB @ 5GHz)
MGF4941 from Mitsubishi 0,25 13,8
MGFC4419 from Mitsubishi 0,28 12,3
MGF4931 from Mitsubishi 0,48 11
ATF-36077 from Agilent 0.32 13
NE3511S02 from NEC 0,25 13
FHX13X from Fujitsu ------ 14
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Design Constraints
Using the Noise Parametersprovided, and following theusual procedure to design ainput and output matching
networks, a LNA with
NF=0,35dB and 13,4dB of gain
9 November 2009 3º Congresso URSI Portugal
MB050109
9 November 2009 3º Congresso URSI Portugal
IF part designed and tested
IF Chain+RF Filter
4.9GHZ; B=600MHzCoupled Line filter
B=200MHz; 31dB; ButterworthMMIC (best response flatness)
Flat gain; 71dB;Digital attenuation
120dB isolation between portsFrequency 600MHz; VCO; MMIC Amp.;
PLL synthesyzer; 7dBm
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9 November 2009 3º Congresso URSI Portugal
Microwave Passive Filter
Central Frequency = 4,9 GHz;
Bandwidth = 800 MHz;
Coupled Lines;
ADS Design aided;
Electromagnetic Simulation.
Substrate – RO4003C
Substrate Thickness H 20 mil
Relative Dielectric Constant εr 3,38
Conductor Thickness T 0,35μm
Dielectric Loss Tangent tan δ 0,0021
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 190 20
-60
-50
-40
-30
-20
-10
0
-70
10
frequency [GHz]
[dB
]
S - parameter
dB(S(2,1))
dB(S(1,1))
dB(S(1,2))
dB(S(2,2))
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9 November 2009 3º Congresso URSI Portugal
L1 C1
L2 C2
L3
C3
Vcc =8V
IF Pre - Amplifier
Gain = 31 dB
Slope Compensation Network;
Gain variation with frequency;
Gain variation with Temperature;
S-Parameters Simulation.
High Q filter;
Central Frequency = 600 MHz;
Bandwidth = 200 MHz;
T configuration
Butterworth Prototype;
Hand made Inductances
ADS Design aided;
Amplifier Filter
P1dB = -24 dBm
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9 November 2009 3º Congresso URSI Portugal
Vcc =8V
4 4
µC
IF Amplifier
Gain = 71 dB;
Flat gain;
Digital attenuation control;
Slope Compensation Network;
Gain variation with frequency;
Gain variation with Temperature;
S-Parameters Simulation.
P1dB = -61 dBmIP3= -41 dBm
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Converter
75 1455 210
-28
-18
-8
-38
2
Frequency [MHz]
[dB
m]
Converter output
LPF
LPF
LPF
LPF
I
Q
LO0º
LO90º
Zero – IF Conversion (LB = 100MHz);
Phase (I) and Quadrature (Q) Modulation;
Signal Amplification (GSINAL = 16 => 25 dB);
Port Isolation = 120 dB;
Suitable for Stokes Parameters Calculation;
Microstrip Lines with equal lengths;
Protection (outside interference & parasitics).
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9 November 2009 3º Congresso URSI Portugal
Local Oscillator
VCO
50Ω
50Ω
50Ω
50Ω
0 dBm
0 dBm
10 dBm
90º
90º
0º
0º≈ 7 dBm
≈ 7 dBm
≈ 7 dBm
≈ 7 dBm
R1
R2
R2
R3
R3
PLL
0,6 dBm
Frequency = 600 MHz with 7 dBm;
Provides the converter with 4 signals
PLL Sinthesized;
Microstrip Lines with equal lengths;
Protection (outside interference & parasitics).
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9 November 2009 3º Congresso URSI Portugal
Full 4-channel Digital CorrelatorCorrelations computed in aFPGA after signal digitalization(ADC interleaving) and outputsI,Q,U Stokes signals:
Why an FPGA Cyclone II from ALTERA?
• Embedded Multipliers;
• Number of pins;
• Frequency.
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9 November 2009 3º Congresso URSI Portugal
Digital CorrelatorISA Interface output
• ADCs AD9481 from Analog
Devices.
• 250 Msps
• 8 bits of resolution
Analog inputs • FPGA EP2C8Q208C7 Cyclone II from ALTERA
• 8256 LE.
• Number of 9 bits multipliers = 36;
• 208 pins
• Speedgrade 7
Active Serial mode
programming interface
Cristal Oscilator
100 MHz
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9 November 2009 3º Congresso URSI Portugal
1. Signals correlation from the 4 ADCs, (8 bits sum and
multiplications every)
2. Integration of correlated signals.
3. Output Stokes parameters to PC104
FPGA calculates the Stokes parameters (I, Q, U).
(VHDL code implementation by Francisco Fernandes)
Full Digital Correlator
FPGA is an ALTERA
Cyclone II and works at
100 MHzFPGA
I, Q, U
PC104
N
N+1
100 MHz
Cyclone II
ADC 1
N
N+1ADC 2
N
N+1ADC 3
N
N+1ADC 4
8 bits of resolution200 MSPS
0,5Vpp
I,Q,U,V=F(ADC1,ADC2,ADC3,ADC4)
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Main Features of PC104 (MOPSlcdLX*)
Hardware• 500 MHz AMD LX800
TM
Processor• 256 MByte DDR-RAM• ChipDisk IDE 1 GByte• Support: ISA, Ethernet• Power supply: 5V
Software• Linux, kernel 2.4• Dedicated, custom-made
software for FPGA communication via ISA bus (C lang. –implemented by Francisco Fernandes).
• SSH File transfer.
* www.kontron.com/MOPS
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9 November 2009 3º Congresso URSI Portugal
LIRAeLinux for Radio Astronomy embedded
LIRAe is a microlinux distribution, to run on CPU embedded systems and control radioastronomy digital correlators based on FPGA chips.
The system was tested and runs on a PC104 from Kontron, model MOPSlcdLX.
Download available soon.LIRAe main developer: Francisco Fernandes
email : [email protected]
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9 November 2009 3º Congresso URSI Portugal
Mechanical Layout
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9 November 2009 3º Congresso URSI Portugal
Receiver photo
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9 November 2009 3º Congresso URSI Portugal
Conclusion : Radiometer facts
Tsys < 20 K; B = 200 MHz; 104 dB gain
High-performance IF strip
Latest RF tech+ microstrip design + MMIC
New Radioastronomy Design:
Zero-IF Converter + I,Q modulation
Digital Correlator : 4-channel, FPGA implemented processing 16Gbps!
An SKA (Potential!) Digital Demodulator
Dynamic Range: Total=20dB, Instantaneous=80dB
Suitable for state of the art RA applications.
MoU with ESA Planck Science Team.27
FIM
Muito obrigado pela atenção...
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