A 340 GHz cryogenic amplifier based spectrometer for space based atmospheric science applications

The operating frequency of InP high electron mobility transistor (HEMT) based amplifiers has moved well in the submillimeter-wave frequencies over the last couple of years. Working amplifiers with substantial gain in waveguide packages has been reported beyond 700 GHz. When cooled cryogenically, they have shown significant improvement in their noise temperature. This has opened up the real possibility of cryogenic amplifier based heterodyne receivers at submillimeter wavelengths for ground-based, air-borne, and space-based instruments for astrophysics, planetary, and Earth science applications. This paper provides details of a cryogenically cooled 340 GHz sideband separating spectrometer with InP HEMT receiver front-end for atmospheric science applications. We will show that these cooled amplifiers are now mature enough to be used for air-borne and space-based missions.