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Central Development Laboratory

Central Development Laboratory. IEEE Tour April 2003. (Adapted from John Webber’s Viewgraphs, April 2002 Presented tonight by Skip Thacker). Block Diagram. CDL Activities. Low-noise Amplifiers Passive Electromagnetic Devices ALMA SIS mixers for Bands 3 & 6

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Central Development Laboratory

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  1. Central Development Laboratory IEEE Tour April 2003 (Adapted from John Webber’s Viewgraphs, April 2002 Presented tonight by Skip Thacker)

  2. Block Diagram IEEE CDL Tour April 2003

  3. CDL Activities • Low-noise Amplifiers • Passive Electromagnetic Devices • ALMA SIS mixers for Bands 3 & 6 • ALMA Front End LO for All Bands • ALMA Correlator • Other Digital Projects • L-band Array Receiver (with Green Bank) IEEE CDL Tour April 2003

  4. Amplifier Goals • Keep up with receiver builds • Improve production efficiency • Develop InP amplifiers for bands down to 1 GHz • Start replacement of antiquated test equipment IEEE CDL Tour April 2003

  5. Production Amplifiers Band (GHz) Noise (K) Comment Band (GHz) Noise (K) Comment 0.3-0.4 2.0 balanced C 4-6 9 0.4-0.5 2.0 balanced C/X 3-13 5 InP 0.5-0.7 2.0 balanced X/Ku 8-18 6 InP 0.7-0.9 3.0 balanced K 18-26 9 InP 0.9-1.2 3.0 balanced Ka 26-40 14 InP 1.2-1.7 3.0 Q 40-50 18 InP 1.7-2.6 4.5 V 65-90 45 InP 2.6-4 5.2 W 68-116 60 InP IEEE CDL Tour April 2003

  6. Electromagnetics • Feeds for GBT: 26-40 and 68-92 GHz • Feed for EVLA: 1.2-2.0 GHz • G/T slightly worse at zenith • G/T much improved integrated over sky • Scaled versions for 2-4 and 4-8 GHz • Optics for ALMA Band 6 (211-275 GHz) IEEE CDL Tour April 2003

  7. GBT 68-92 GHz Feed Design IEEE CDL Tour April 2003

  8. SIS Mixer Objectives • ALMA Band 6 (211-275) GHz sideband-separating, balanced mixer • ALMA Band 3 (84-116 GHz) elemental mixer for use by Herzberg Institute • Internal IF amp for 8 GHz bandwidth • Band 6 cartridge development • Automated mixer testing IEEE CDL Tour April 2003

  9. Band 6 Waveguide-HybridSIS Mixer Block IEEE CDL Tour April 2003

  10. Band 6 Waveguide-HybridSIS Mixer Block Detail IEEE CDL Tour April 2003

  11. New Band 3 ElementalSIS Mixer Wafer IEEE CDL Tour April 2003

  12. New Band 3 ElementalSIS Mixer Wafer Detail IEEE CDL Tour April 2003

  13. New Band 3 ElementalSIS Mixer Wafer Detail IEEE CDL Tour April 2003

  14. Band 6 BalancedMixer-preamp Assembly IEEE CDL Tour April 2003

  15. SIS Mixer Test FacilityWith Two 4K Dewars IEEE CDL Tour April 2003

  16. ALMA Front End LO Tasks • YIG-Tuned-Oscillator-based drivers • Low phase noise lock loops • Final power amplifiers • High-frequency multipliers IEEE CDL Tour April 2003

  17. 96-104 GHz Power-combiningBalanced Power Amplifier IEEE CDL Tour April 2003

  18. ALMA Band 6 LO Prototypefor SIS Mixer Test Facility IEEE CDL Tour April 2003

  19. Prototype Warm Multiplier Assembly IEEE CDL Tour April 2003

  20. Band 6 CartridgeLO components IEEE CDL Tour April 2003

  21. ALMA Correlator • 64 antennas • 8 IF bands per antenna • 4 Gsamples/sec per IF band, 2 bits/sample correlated • 1024 lead + 1024 lag correlations per baseline • 30 km maximum baseline delay range • Full polarization capability plus autocorrelation • Digital filter for bandwidths <2 GHz • Switch modes in less than 1.5 seconds • This requires 4,194,304 multiply-and-add correlators at 4 GHz rate • Total computation rate is 1.7 X 1016 multiply-and-add operations/sec IEEE CDL Tour April 2003

  22. FIR Filter Card & Station Card FIR Filter Card Station Card IEEE CDL Tour April 2003

  23. Station Card in Test Fixture IEEE CDL Tour April 2003

  24. Correlator Card Back IEEE CDL Tour April 2003

  25. Front and Rear Views IEEE CDL Tour April 2003

  26. Station Bin IEEE CDL Tour April 2003

  27. Beam-Forming Array Receiver • Objective: synthesize multiple beams for 1300-1750 GHz, where conventional feed arrays are impractical on the GBT • Approach: oversample e-m field at focal plane with closely spaced feeds • Challenges: • Achieve system noise temperature close to that of a conventional receiver • Achieve mechanical and electronic stability sufficient for reliable calibration IEEE CDL Tour April 2003

  28. Beam Forming Array IEEE CDL Tour April 2003

  29. Beam-Forming Array Feeds • Array of dipoles samples focal plane • Tuned for 1300-1750 MHz • 37-element prototype provides 7 beams on the sky IEEE CDL Tour April 2003

  30. Prototype Dipole IEEE CDL Tour April 2003

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