W-band direct detection radiometers using metamorphic HEMT technology

At this paper we report on a W-band direct detection radiometer cascading a single-pole four-throw switch with integrated 50 Ω load as a reference noise source, a 3 x 20 dB low-noise amplifier chain, and a broadband Schottky-diode detector. All components are designed and fabricated in 100 nm metamorphic high electron mobility transistor (mHEMT) technology and use waveguide packaging. By using 2 channels of the switch module the Dicke-principle is implemented to drastically reduce the inherent amplifier noise. The multi-throw switch insertion loss is less than 3.5 dB on the chip level and 4.4 dB on the module level. The entire W-band direct detection radiometer chain is also integrated on a single chip and packaged into a waveguide module, which was successfully tested and is now ready for system integration.