1. Cambridge, Dec 2010Considerations for AA-lo LNA Dr Saswata Bhaumik PDRA of: Dr Danielle George The University of Manchester

2. Cambridge, Dec 2010Considerations for AA-lo LNA 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. Cambridge, Dec 2010Considerations for AA-lo LNA AA-lo hybrid LNA simulations LNA1 LNA2

4. Cambridge, Dec 2010Considerations for AA-lo LNA AA-lo LNA Simulated results: 1.Two hybrid LNA designs. 2.2-stage LNAs with differential input and single ended output. 3.Enhancement mode pHEMTs of Avago Technology 4.Operational from 50MHz to 400MHz. 5.LNA1: Gain above 25dB. NT below 35Kelvin between 100MHz and 450MHz 20Kelvin at 330MHz. 4V – 121mA drain bias (at PSU). P1dB IN point of -23dBm at 0.4GHz. 6.LNA2: Gain above 36.7dB. NT below 36Kelvin. P1dBIN is -24dBm at 0.4GHz. 3V – 60mA drain bias and 0.5V at gate 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

5. Cambridge, Dec 2010Considerations for AA-lo LNA List of Measured HEMT Samples Process Different S-parameter NoiseDetails Sizessamples Samples Samples 188x47x2 150nm GaAs pHEMT 29 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 66 6x3 3x2 70nm GaAs mHEMT 7 1 1x6- 150nm GaAs pHEMT 81 1x6 - 100nm InP pHEMT 933x6-100nm GaAs pHEMT Total 52 190 54 9 types Ongoing/Future characterisation work: 1.HEMTs of 2/3 more processes 2.Further Characterisation of 2 of 9 above processes 3.Cryogenic characterisation of HEMTs of shortlisted processes MMIC Parameters: 1.Reproducibility 2.Reliability 3.Yield 4.Future Availability 5.Power, Temperature, Cost

6. Cambridge, Dec 2010Considerations for AA-lo LNA Process considerations Process Investigation based on power efficiency Important parameters: 1.Noise Measure 2.Position Gamma Opt in Smith Chart 3.Temperature dependency 4.Power efficiency Loci of Γ opt

7. Cambridge, Dec 2010Considerations for AA-lo LNA Temperature Dependency 1.Temperature fluctuation varies gain and NT 2.Temperature stabilisation is vital for long observations 3.Optimum biases change with temperature 4.Temperature stabilisation? Process Investigation based on temperature dependency

8. Cambridge, Dec 2010Considerations for AA-lo LNA Interface between antenna and LNA/balun is crucial for noise and gain ripple. Consideration must be given to practical implementation. Options – 1.Direct connection between Antenna and LNA –Differential Antenna and Differential/pseudo Differential LNA –Single-ended Antenna and Single-ended LNA 2.Balun in the Interface –Differential Antenna and Single-ended LNA (feasible for AA-lo SKA) Interface with Antenna

9. Cambridge, Dec 2010Considerations for AA-lo LNA 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.