Evolution of the 2-PAD Front-End

1
Evolution of the 2-PAD Front-End
2-PAD Dual-Polarisation All Digital Aperture
Array (DS4T6)
3rd SKADS Workshop April 2008
2
2-PAD Analogue Signal Path
Bunker RFI Shield
Custom Analog Chip
Custom Digital Chip
Ant. polarisation
PCB Plug
HSS interface
4 off Beamformer Processors
Processor
Switch
PSU
4-bit ADC
Noise source
Beamformer Processor
Beam combing Processor
ve
Reg

4 i/ps each
.......
PCB
Station processors
Custom Analog Chip(s)
.......
From other beamformer proc.
Analog Twisted Pair
PSU
LNA
4-bit ADC
256 elements x2 polarisations
128 analog i/ps Digital beams out
4 i/ps each
...
Total 512 inputs
...
Control Processor
Analog sig. conditioning control
Line Tx/Rx
Station Control
Buffers
Time standard
3rd SKADS Workshop April 2008
3
2-PAD Front-End Module
Front-End Module
Shielded Bunker Wall
Line Driver
LNA
Amplification
CoaxialCable
TwisterPair
ReceiverBoard
Antenna
Noise Diode
Power Regulator
3rd SKADS Workshop April 2008
4
Previous Front-End Prototypes
Version Input Output Voltage Power Gain
Gain Chain v1 single differential 5V 150mA8.5V 320mA 3.47 W 80 dB
Gain Chain v2 single single 5V 150mA 8.5V 160mA 2.11 W 80 dB
Gain Chain v3 single single 5V 150mA 8.5V 60mA 12V 525mA 7.56 W 68 dB
Gain Chain v1
Gain Chain v2
Gain Chain v3
Several Issues Identified!
3rd SKADS Workshop April 2008
5
Next Generation Front-End

• Address identified issues, plus
• Dual-polarisation front-end module
• Mass production plastic enclosure
• Cheap metallisation of surfaces
• Temperature stabilisation/cooling

Still More Outstanding Issues!
3rd SKADS Workshop April 2008
6
Antenna Specific LNAs
Embrace Tile
Oxford Log-Period Dipole
Flowpad
3rd SKADS Workshop April 2008
7
Output Twisted Pair Cable

• Coaxial cable problematic
• Results in very high connector densities
• Expensive
• Twisted pair (CAT7)
• Cheaper and more channels per area
• Requires differential output

3rd SKADS Workshop April 2008
8
Current Front-End Version
Antenna Specific LNA
Quad Channel Amplifier Box
Coax / Semi Rigid (1m)
CAT7(20m)
Balun
TERA
Amp1
Amp2
Amp3
SMA
LNA
SMA
SMA
Amp?
3rd SKADS Workshop April 2008
9
Conclusion and Further Work

• First revision of current version nearing
  completion

• We will continue to evolve the 2-PAD front-end
  until it reaches the functionality appropriate
  for the SKA

3rd SKADS Workshop April 2008
10
Gain Chain Versions 1 to 3
Version Input Output Voltage Power Gain
Gain Chain v1 single differential 5V 150mA8.5V 320mA 3.47 W 80 dB
Gain Chain v2 single single 5V 150mA 8.5V 160mA 2.11 W 80 dB
Gain Chain v3 single single 5V 150mA 8.5V 60mA 12V 525mA 7.56 W 68 dB
Section Amplifier Gain 1dB Comp. NF Voltage
Amp1 HMC374E 15 dB 22 dBm 1.5 dB 5.0V
Amp2 GALI-52 21 dB 15.5 dBm 2.7 dB 5.0V
Amp3 ERA-50SM 20 dB 17.5 dBm 3.3 dB 8.5V
Amp4 (GC1) MERA-7456 24 dB 18.5 dBm 2.7 dB 8.5V
Amp4 (GC2) GALI-84 24 dB 21.5 dBm 4.3 dB 8.5V
Amp4 (GC3) HELA-10 12 dB 30 dBm 3.5 dB 12V
3rd SKADS Workshop April 2008
11
Gain Chain Version 4 Design

• Commercial Front-end Module
• http//www.nuwaves-ltd.com/pdf/uHILNA20Data20She
  et.pdf

3rd SKADS Workshop April 2008
12
Oxford Log-Periodic Dipole

• Physical Properties
• beam width 22 (HPHW)
• forward gain 11.5dBi
• low horizon side lobes
• frequency range 0.3-1.0GHz
• return loss better than -15dB

3rd SKADS Workshop April 2008
13
Oxford Log-Periodic Dipole
forward gain
simulation limitation
cross-polarisation

• Physical Properties
• beam width 22 (HPHW)
• forward gain 11.5dBi
• low horizon side lobes
• frequency range 0.3-1.0GHz
• return loss better than -15dB

3rd SKADS Workshop April 2008
14
Complete Test Chain

• Commercial LNA
• (for testing this antenna only)

Amplifier Box
SignalConditioningModule
3rd SKADS Workshop April 2008