1. Technology Perspective and results with mHEMTs
Jan Geralt Bij de Vaate
ASTRON

2. Specification R Schillizi et. al. Sept. ‘07
Tinstrument= 40K (excluding sky noise), goal 30K
BW 70MHz – 1.0 GHz (two systems)
Survey speed ~1/T2
Sensitivity ~1/T
SKADS Workshop 2007

3. Costing
A 9 million element system with a total system cost of 250M € can spend:
1,5 € per LNA per Kelvin improvement (Survey)
Or 8,5 € for 5 Kelvin improvement, again for Surveys
Given a bare die costs of:
0,5 € for Silicon technologies (only inch wafers)
2 € for GaAs technologies ( inch wafers)
Low cost technologies cannot compromise on noise!
SKADS Workshop 2007

4. Technology GaAs PsHEMT / mHEMT SiGe BJT with b0 =100: FMIN~30K CMOS
In principle similar to GaAs
SKADS Workshop 2007

5. PsHEMT 0.2um technology OMMIC differential LNA 2109 ASTRON design
SKADS Workshop 2007

6. InP
Differential LNA
NGST
SKADS Workshop 2007

7. mHEMT 70nm OMMIC technology 250GHz fT Differential design
Optional on-chip biasing
SKADS Workshop 2007

8. mHEMT 70nm OMMIC technology 250GHz fT Differential design
Optional on-chip biasing
SKADS Workshop 2007

9. mHEMT ATNF01_40LNA_05A, Russel Gough
70nm OMMIC technology
Designed for GHz band
4-stage low-noise amplifier
Transistors: 6-fingers, 90um gate width
Bias:
Vds = 1.0 V
Id = 13 mA
SKADS Workshop 2007

10. ATNF01_40LNA_05A 10 circuits were delivered
sample of 4 was measured
1 circuit was unstable (|S11|>1)
The performance of remaining 3 circuits was similar
Measured gain is greater than modelled
Input and output match is poorer than expected
SKADS Workshop 2007

11. SiGe IBM technology 8HP (0.13µm) : sub 0.5dB noise figure possible
0.25dB for 9HP??
(relative) high Rn
Good power match possible
Limited cooling boosts current gain β:
Weinreb 2005
SKADS Workshop 2007

12. SKADS Workshop 2007

13. SKA / LOFAR workshop! (or focussed session) vaate@astron
SKADS Workshop 2007

14. Conclusion SKA specifications for AA within reach it seems but…
T coupling (<5) (active reflection coefficient)
T spill-over, ground noise (<5)
T antenna losses (<5)
Technology choice will be based on performance
Good case for III/V, but also CMOS
SKADS Workshop 2007