1. Institute of Astronomy and Astrophysics, Academia Sinica (ASIAA)
ALMA Band-1 Receiver
Chau-Ching CHIONG 章朝盛
Institute of Astronomy and Astrophysics, Academia Sinica (ASIAA)

2. Contributions from … ASIAA National Taiwan University EE
Microwave Group: Dr. Y.-J. Hwang, Dr. Y.-F. Kuo, Dr. C.-C. Lin, C.-C. Chuang, C.-T. Ho.
Receiver Group: Dr. M.-T. Chen, T.-S. Wei.
National Taiwan University EE
Prof. H. Wang: Dr. Z.-M. Tsai, Dr. B.-J. Huang, W.-J. Tzeng, Y.-C. Wu, B.-H. Tsai, C.-C. Hung.
National Central University EE
Prof. H.-Y. Chang: S.-H. Weng.
Prof. Y.-S. Lin: Y.-S. Hsieh.

3. Science of ALMA Band 1 (30-45 GHz)
High resolution Sunyaev-Zel’dovich effect imaging
Anisotropy of cosmic microwave background radiation
High-redshifted CO lines
Probing magnetic field strength via Zeeman measurement
Transistion
Frequency
(GHz)
Zeeman splitting (Hz/uG)
CCS JN = 32-21
33.75
0.70
CCS JN = 43-32
45.38
0.63
SO JN = 10-01
30.00
1.74
SiO v=1, J =1-0
43.12
Very small
Transistion
Redshift range
CO J=1-0
1.55 – 2.67
CO J=2-1
4.11 – 6.35

4. Band-1 Development Plan
International cooperation of Taiwan (ASIAA), Canada (HIA) and Chile (Uni. of Chile).
ASIAA deliver key components, mostly in MMIC technologies (LNA, mixer, filter, IF amp.), while HIA focuses on optics, LNA (hybrid) and system integration.
Proto-type receiver will be assembling in Chile.
HIA Band-1 cartridge layout
Main challenges:
Longest wavelength, thus largest component size.
LNA Noise < 7 K.
More than 60 copies required.

5. Band 1 System Requirements
Observation frequency: GHz (36%)
Operation mode: single side band (USB), dual linear polarization feed
Image suppression: > 20 dB
Aperture efficiency: > 78 %
IF bandwidth: 4-12 GHz
IF output power: -31 to -18 dBm. IF power variation: 6dB peak-to-peak in any 2GHz BW. 10 dB peak to peak across the complete IF band.
Receiver noise temperature:
17 K (80 % bandwidth) and 28 K (full bandwidth) when operating at 15 K.
LO tuning range: GHz (18.9%). No mechanical tuning
RMS LO phase noise in jitter: 53 fs (short-term), 17.7 fs (long-term)
LO output power: 10 mW
Front-end cartridge size: diameter 170mm, length ~ 500mm

6. ALMA Band 1 Front-end System
15K
Optics design + Feedhorn
OrthoMode Transducor (OMT)
Cryogenic Low Noise Amplifier (LNA)
Bandpass Filter + Mixer
Intermediate Frequency (IF) Amplifier
Local Oscillator (LO) + PLL

7. Reasons for MMIC Approach
Easy integration
High reliability
Mass production (> 200 pcs.)
Low cost (?)
But still high noise.
Hybrid IC
MMIC
Design Time
Fast
Slow
Noise
Low
High
Assembling & Mass Production
Hard
Easy
Circuit Density
Large
Small
Integration
Experts No
Yes
Hybrid X-band LNA from JPL, Weinreb (2007)

8. MMICs for Front End

9. Q-band Cascode PHEMT Mixer
The cascode mixer using WIN 0.15 um pHEMT shows
Good conversion gain flatness over 4-12GHz IF frequency.
Low LO power drive.
Z.-M. Tsai et. al, EuMIC, 2009

10. 31-45 GHz 0.15 um MHEMT LNA |S| (dB) |S| (dB)
2f100mm 2-stage mHEMT LNA
|S| (dB)
Both with 2 mm x 1 mm
Vd=2V, Id_dev=37mA, Id_mea=30, 33mA
2f50mm 3-stage mHEMT LNA
|S| (dB)
December 01-03, 2010
Vd1=Vd2=Vd3=1V, Id1=Id2=Id3=10mA

11. Cryogenic Measurements
Packaging
Test Dewar
Weng et al., EuMIC, 2011

12. Balanced LNA as Second Stage
The same design of the 3-stage version.
Better input/output matching.
December 01-03, 2010

13. IF Amplifier
Chiong et al., EuMIC, 2009

14. Integrated LNA-Mixer-Filter-IFA Chip
LO Input
Bandpass filter
(Lin et al. ‘09)
IF amplifier
LNA
cascode HEMT mixer
2nd-stage LNA
Total DC power < 150mW
Highly integrated design of the module.
Saving space inside the cryogenic section of the front-end cartridge.
Reducing the possibility of failure in assembling.

15. LO System: YTO or VCO

16. YIG-Tuned Oscillator (YTO) in Current ALMA System
Coarse/fine tune
30 MHz ref.
Excellent phase noise

17. YTO + Doubler: Phase Noise
Jitter (1 kHz to 1MHz) ~ 45 fs
ALMA spec: 53 fs

18. VCO Approach
VCO has almost all advantages over YTO except phase noise.
PLL board for YTO has to be modified for VCO operation, because single-tuned VCO has large gain and large gain variation.
Frequency divider is added so that VCO-based PLL can be used in ALMA environment (using 30 MHz reference).

19. Differential VCO layout
Tuning Voltage
RF out
PN ~ MHz offset
-0.6 V
-2.5 V
RF out
WIN 0.15 um HBT
Total dc power consumption: 85 mW
Chiong et al., EuMIC, 2008

20. Adaptive Loop Bandwidth Technique
The VCO gain variation is large. For osc. Freq. > 33GHz, Kvco ~ 200MHz/V, with Filter 1, PLL BW~ 200 kHz.
By switching to Filter 2, the PLL BW can be increased from 200kHz to 1MHz.
The phase noise can be improved more than 22dB at the offset frequency of 250kHz under such adaptive loop bandwidth. 20

21. Phase Locked Spectra of VCO

22. Phase Noise Comparison between Phase-locked YTO and VCO
RMS Jitter/Degree of YTO to 1MHz) is 44.6fs/0.59o
RMS Jitter/Degree of VCO to 1MHz) is 63.8fs/0.77o 22

23. YIG vs. VCO
Using adaptive loop bandwidth technique, the whole tuning range of VCO can be locked by single PLL board.
Phase noise within the loop bandwidth (~ 100 kHz) is compatible.
Worse VCO phase noise at larger offset frequency contribute a lot of noise.
Need more advanced InP HBT to meet ALMA spec.

24. Possible Timeline for Band-1
2012: Proposal to ALMA
2013: Preliminary Design Review. First prototype front-end
2014: Critical Design Review. Production starts
2018: Project finishes

25. Thank you.