Low noise amplifiers for 140 GHz wide-band cryogenic receivers

We report S-parameter and noise measurements for three different InP 35 nm gate-length High Electron Mobility Transistor (HEMT) Low Noise Amplifier (LNA) designs operating in the frequency range centered on 140 GHz. When packaged in a WR-6.1 waveguide housing, the LNAs have an average measured noise figure of 3.0 dB-3.6 dB over the 122-170 GHz band. One LNA was cooled to 20 K and a record low noise temperature of 46 K, or 0.64 dB noise figure, was measured at 152 GHz. These amplifiers can be used to develop receivers for instruments that operate in the 130-170 GHz atmospheric window, which is an important frequency band for ground-based astronomy and millimeter-wave imaging applications.