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Considerations for AA-lo LNA

Considerations for AA-lo LNA. Dr Saswata Bhaumik PDRA of : Dr Danielle George The University of Manchester. Overview. Hybrid LNA simulations Performances of LNA1 and LNA2 MMIC process considerations Reproducibility, Repeatability, Yield, Availability, Power, Temperature Stability

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Considerations for AA-lo LNA

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  1. Considerations for AA-lo LNA Dr Saswata Bhaumik PDRA of: Dr Danielle George The University of Manchester

  2. Overview • Hybrid LNA simulations • Performances of LNA1 and LNA2 • MMIC process considerations • Reproducibility, Repeatability, Yield, Availability, Power, Temperature Stability • Interface with Antenna • Investigation of interface between LNA and Antenna is very important

  3. AA-lo hybrid LNA simulations LNA2 LNA1

  4. AA-lo LNA • AA-lo LNA: • Low loss Baluns. • Single ended LNAs. • Overall noise figure should be less than sky noise. • AA-lo MMIC LNA: • Matured process • Excellent repeatability and yield • Low cost • High transconductance and low noise • Simulated results: • Two hybrid LNA designs. • 2-stage LNAs with differential input and single ended output. • Enhancement mode pHEMTs of Avago Technology • Operational from 50MHz to 400MHz. • LNA1: • Gain above 25dB. • NT below 35Kelvin between 100MHz and 450MHz 20Kelvin at 330MHz. • 4V – 121mA drain bias (at PSU). • P1dBIN point of -23dBm at 0.4GHz. • LNA2: • Gain above 36.7dB. • NT below 36Kelvin. • P1dBIN is -24dBm at 0.4GHz. • 3V – 60mA drain bias and 0.5V at gate

  5. List of Measured HEMT Samples Process Different S-parameter Noise Details Sizes samples Samples Samples 1 8 8x4 7x2 150nm GaAs pHEMT 2 9 9x4 5x2 150nm GaAs mHEMT 3 4 4x4 4x2 130nm GaAs pHEMT 4 7 7x4 4x2 100nm InP pHEMT 5 8 8x3 8x2 150nm GaAs mHEMT 6 6 6x3 3x2 70nm GaAs mHEMT 7 1 1x6 - 150nm GaAs pHEMT 8 1 1x6 - 100nm InP pHEMT 9 3 3x6 - 100nm GaAs pHEMT Total 52 190 54 9 types Ongoing/Future characterisation work: HEMTs of 2/3 more processes Further Characterisation of 2 of 9 above processes Cryogenic characterisation of HEMTs of shortlisted processes MMIC Parameters: Reproducibility Reliability Yield Future Availability Power, Temperature, Cost

  6. Process considerations Process Investigation based on power efficiency Loci of Γopt Important parameters: Noise Measure Position Gamma Opt in Smith Chart Temperature dependency Power efficiency

  7. Temperature Dependency Process Investigation based on temperature dependency Temperature fluctuation varies gain and NT Temperature stabilisation is vital for long observations Optimum biases change with temperature Temperature stabilisation?

  8. Interface with Antenna Interface between antenna and LNA/balun is crucial for noise and gain ripple. Consideration must be given to practical implementation. • Options – • Direct connection between Antenna and LNA • Differential Antenna and Differential/pseudo Differential LNA • Single-ended Antenna and Single-ended LNA • Balun in the Interface • Differential Antenna and Single-ended LNA (feasible for AA-lo SKA)

  9. Conclusions and Further Work • AA-lo has different LNA design requirements to AA-mid. • HEMTs of 9 processes investigated – 2 processes will be further investigated. • 2/3 more processes will be investigated. • Different pHEMT topologies superior to mHEMT topologies for AA SKA (considering factors discussed in previous slides). • Different processes suitable for different frequency bands (AA-lo and AA-mid). • MMIC version of AA-lo LNA has been designed for fabrication.

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