A 16 GHz Bandwidth Cryogenic IF Amplifier with 4-K Noise Temperature for Sub-mm Radio-Astronomy Receivers

Isaac Lopez-Fernandez*, Juan D. Gallego, Carmen Diez, Inmaculada Malo-Gomez, Ricardo I. Amils, Ralf Fluckiger, Diego Marti, Ronald Hesper

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

1 Citation (Scopus)
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The major mm and sub-mm radio-astronomy observatories are prioritizing instantaneous bandwidth widening for their current or planned upgrades this decade. We present an ultra-wide-band and ultra-low-noise cryogenic hybrid amplifier with 4 K (NF  =  0.06 dB) average noise temperature in the 2-18 GHz band when cooled to 6 K. It is based on a 100 nm gate pseudomorphic InP HEMT with outstanding characteristics. This demonstration amplifier meets the noise and IF bandwidth demands of ALMA next generation receivers, doubling the present maximum IF instantaneous bandwidth with state-of-the-art noise performance, with a gain flatness of ±0.8 dB, and output return loss better than 15 dB over 85% of the band. It can be used in the 1-19 GHz range with negligible degradation, and a tentative test has been performed with a 602-720 GHz ALMA band-9 DSB SIS mixer, showing a flat-average and low-ripple IF noise level in an 18-GHz wide band down to near DC. A balanced configuration is feasible to improve the input matching.

Original languageEnglish
Pages (from-to)1-10
Number of pages10
JournalIeee transactions on terahertz science and technology
Issue number3
Early online date27-Feb-2024
Publication statusPublished - May-2024


  • Bandwidth
  • Broadband amplifiers
  • Cryogenics
  • cryogenics
  • indium-phosphide pseudomorphic high electron mobility transistor (InP pHEMTs)
  • Logic gates
  • low-noise amplifiers (LNAs)
  • Mixers
  • noise measurement
  • radio astronomy
  • Resonant frequency
  • Standards
  • submillimeter wave
  • superconductor-insulator-superconductor (SIS) devices
  • Transistors
  • ultra-wideband technology


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