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)

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.

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

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.

Band 1 System Requirements Observation frequency: 31.3-45 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: 27.3-33 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

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

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)

MMICs for Front End

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

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

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

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

IF Amplifier Chiong et al., EuMIC, 2009

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.

LO System: YTO or VCO

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

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

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).

Differential VCO layout Tuning Voltage RF out PN ~ -100 dBc/Hz @ 1MHz 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

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

Phase Locked Spectra of VCO

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

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.

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

Thank you.