220 GHz low-noise amplifier modules for radiometric imaging applications

G-band low-noise amplifier (LNA) modules have been successfully developed for use in high-resolution radiometric imaging applications. The WR-5 waveguide modules contain a four-stage 220 GHz cascade LNA MMIC and two microstrip-to-waveguide transitions which were realized on 50 µm thick quartz substrates. The monolithic amplifier circuits were fabricated using a well proven 0.1 µm InAlAs/InGaAs metamorphic high electron mobility transistor (MHEMT) technology in combination with grounded coplanar waveguides (GCPW). Furthermore, an MMIC based 220 GHz direct detection radiometer was developed, for the first time, containing three amplifier modules connected in series and demonstrating a small-signal gain of more than 50 dB over the frequency range from 209 to 2l7 GHz.