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)