Towards Robust Solar-powered SKA-low Front-end
Budi Juswardy, JG Bij de Vaate, Franz Schlagenhaufer, Shantanu Padhi & Peter HallICRAR/ Curtin
Path to SKA-low WorkshopPerth, 6-9 Sept 2011
Master Title
SKA-low LNA: Transistor Selection
Manfc. Model No. Low Freq. (Mhz)
High Freq. (Mhz)
NF (dB)
OTOI (dBm)
Pout @1dB (dBm)
Gain (dB)
Opt. Volt (V)
Current (mA)
Tech. Packaging Cost (US$/unit)
@1k
Avago ATF-54143 450 6000 0.5 36.2 20.4 16.6 3 60 E-pHEMT SOT-343 2.29
NXP BF-U725F DC 12000 0.45 17 8.5 20 3-10 40 NPN SiGe
SOT-343 0.22
RFMD SPF-5122Z 50 4000 0.6 38 23 19 3-5 90 pHEMT 2x2QFN 2.23
SKY SKY65050-372LF
450 6000 0.45 23.5 10.5 15.5 3 20 N pHEMT SC-70 0.46
SKY SKY67101-396LF
400 1200 0.55 33.8 19.2 18.7 4 54 N pHEMT 2x2QFN 2.2
Minicircuit
S/TAV581 450 6000 0.5 30 20 17 3 30 E-pHEMT SOT-343 1.19
Minicircuit
SAV541 450 6000 0.5 33 20 17 3 60 E-pHEMT SOT-343 1.39
Minicircuit
SAV551 450 6000 0.5 25 18 16 3 15 E-pHEMT SOT-343 0.99
Mimix CFS-0303 100 10000 0.3 33 17 19 3 60 pHEMT SOT-343 nil
Mimix CFS-0103 100 10000 0.4 26 16 19 3 40 pHEMT SOT-343 nil
Infineon BFP-720 (F/ESD)
40 10000 0.5 22 6.5 26 2 – 4 20 SiGe:C SOT-343 0.51
Infineon BFP-740 (F/ESD)
40 10000 0.5 25 10 27 2 – 4 30 SiGe:C SOT-343 0.48
Infineon BFR-720-L3RH
40 10000 0.5 20.5 6 24 2 – 4 20 SiGe:C TSLP-3-9 0.47
Infineon BGB-707L7ESD
50 10000 0.4 13.6 10 15 1.8–4
2 – 25 SiGe:C TSLP-7-1 0.35
Preliminary Transistor Evaluations
COTS SiGe has higher NF than GaAs, BUT...
– NF optimisation still in progress– Feasible for low-band (<250 MHz)– Reliable, low power consumption
(20mW) SiGe vs (150mW) GaAs
0 100 200 300 400 500 600 700 800 900 10000
50100150200250300350400450500
Noise Temperature Comparison
LNA (using PNA-X)
RFMDBFP720FESDBFU725F10% Sky noise +18K
Frequency (MHz)
Noise
tem
pera
ture
(K)
- Standardise NF measurement– Resolution & Noise BW,– Averaging– Shielding box, ESD diode?
- Accurate trans. noise parameter (model) needed
ESD Diode Selection
Why ESD protection?- Low humidity (both SKA sites)- LNA → ESD sensitive - Environmental protection
● Lightning● Electric dust storms● Human (install & maintain)● Animal?
What level is sufficient?- Statistics (SKA site)- Which standard
Include ESD diodes inLNA design & NF measurement
Master Title
Case Study: MWA-based Front-end
• LNA board draws 450mW• Power budget = 1W • Providing supply for 24 hr• No long-term energy back-up• Panel flat on ground (no tilt)• Evaluate COTS• Regulator module options:
● DC-DC converter (switch mode)● Adv: High efficiency >70%● Disadv: Ripple & switching noise
● Linear Regulator● Adv: Relatively low noise● Disadv: Low Efficiency
Courtesy: MWA website
Master Title
Solar Irradiation vs Power Requirements
HOW & WHY ??
• 1W power budget = 24Wh/day
•• Annual irradiation data at
Murchison:– Min: 3.6kWh/m2/day– Max: 8.4kWh/m2/day– Avg: 6.1kWh/m2/day
Required:– 12V, >2Ah (4Ah) Battery– 10W solar panel – (Area: 0.1 m2)
22-year mean, Courtesy: BOM
Master Title
Solar Irradiation Comparison:Solar Power System Requirements
0 1 2 3 4 50
40
80
120
160
200
Required Battery Capacity vs Reserve Energy
Based on 1W power budget & min. monthly average solar irradiance
Battery capacity
Battery back-up (no. of day)
Bat
tery
Cap
acity
(Wh)1. Meet power demand in winter
2. Min monthly avg. at both SKA sites = yearly avg. in Netherlands3. 50W (Netherlands) → 10W (Australia)4. Battery capacity requirement independent of location
1 2 3 4 5 6 7 8 9 10 11 120123456789
Solar Irradiance Figure (22-year monthly average)
Netherlands & Western Australia
Netherlands GronigenAustralia MurchisonGronigen yearly avgMurchison yearly avg
Month
kWh/m
2̂/day
0 1 2 3 4 50
102030405060708090
100
Optimal Panel Rating vs Reserve Energy
Based on 1W power budget & min. monthly average solar irradiance
GronigenMurchison
Battery back-up (no. of day)
Pan
el ra
ting
(W)
Master Title
1 2 3 4 5 6 7 8 9 10 11 120
10
20
30
40
50
60
70
80
90
Energy produced (Wh/day) using different configurations at SKA site in Australia
Demand: 24Wh/ day (1W Power Budget)Panel rating: Best Winter (10W) & Flat on ground (10W)
Best winter Flat on groundDemand
Month
Wh
/ day
Energy Production Comparison:Panel Tilted vs Flat
- 10W solar panel for 1W power budget (MWA-case study) → based on 10% efficiency, smaller panel if using high efficient panel- Tilting may reduce the required panel rating- Solar power feasible for SKA-low energy generation
Master Title
Case Study: Typical Solar Panel Simulation
SMA core
GND
PV cathode (+)
PV anode (-)
SMA
Via
Cathode (p+)Anode (n+)
Via
0 1 2 3 4 5 6 7 8 9 10-35
-30
-25
-20
-15
-10
-5
0
Generic Solar Panel
Simulation & Measurement
SimulatedMeasured
Frequency (GHz)
dB (S
11)
14
54
2.5 2.5
2
28
24
1
1
52
2.5
85
2
20
+
-
PORTP=1Z=50 Ohm
CAPID=C1C=0.5 pF
DIODE2ID=D2Nu=1.5T=25 DegCIo=1e-6 mAR=8.6k OhmC=0.25 pF
DIODE2ID=D1Nu=1.5T=25 DegCIo=1e-6 mAR=1.6e4 OhmC=0.25 pF
RESID=R2R=1.6e4 Ohm
RESID=R1R=0.001 Ohm
DC_IID=I1Sweep=NoneI=89 mA
PORTP=2Z=50 Ohm
2V, 0.5W panel
Master Title
Study: Solar Panel EM Simulation
0.00 2.00 4.00 6.00 8.00 10.00Freq [GHz]
-30.00
-25.00
-20.00
-15.00
-10.00
-5.00
0.00
dB(S
(1,1
))
HFSSDesign1XY Plot 1 ANSOFT
m3
m2
m1
Curve InfodB(S(1,1))
Simulate1 : Sweep
Name X Ym1 0.4600 -7.6390m2 1.2100 -9.6189m3 3.9800 -26.8927
0.00 2.00 4.00 6.00 8.00 10.00Freq [GHz]
-25.00
-20.00
-15.00
-10.00
-5.00
0.00
dB(S
(1,1
))
HFSSDesign1XY Plot 1 ANSOFT
m1
m2
m3
Curve InfodB(S(1,1))
Simulate1 : Sweep
Name X Ym1 0.4600 -5.2634m2 1.9900 -7.3617m3 5.2400 -9.8113
Electrical connector tracks on the PV panel → radiating structure!
Master Title
Solar Module EMC Evaluation:Radiated & Conducted Emission
1. EMI emissions → Noise & harmonics at SKA-low band2. EMI emission could be augmented:
- Metallic object near PV module- Power cable connection
3. Reduce noise with filters & selection of components → custom made regulator
100 100.5 101 101.5 102 102.5 103-20
-15
-10
-5
0
5
10
EMI Measurement
Voltaic
Frequency (MHz)
dBuV
/m
Field strength, 1kHz RBW
Light source
Rx Ant
Spectrum Analyser
Grounded connectors
distance
EMC Chamber
DUT
Turntable
Real-Time
Oscilloscope
LoadDUT
100-150 MHz, 100 nS time-span, 30 mVpp
Noise from regulator:1. Ripple (low)2. Switch noise
(high-frequency)
Master Title
Conclusion
Low-noise amplifier (LNA):– Potential of SiGe BJT for SKA LNA/ front-end
→ cost, power, reliability– Include ESD diode in LNA design/ evaluation
Solar power generation (Photovoltaic):– Green, free energy– Galvanic isolation (with radio-over-fibre)– Suitability at both SKA sites (irradiation) – EMI emissions with COTS → need custom design – Test EMC of the power system with the antenna
→ (EMC report available at SKA Wiki)