Design of broadband MMIC low noise amplifier at W band using GaAs pHEMTs

A broadband monolithic microwave integrated circuit (MMIC) low noise amplifier (LNA) at W band is designed and fabricated using 0.1 μm GaAs pHEMT process. The design uses a wideband bias decoupling network to suppress low frequency oscillations for improved stability. The fabricated LNA has a measured nominal gain of 10.5 dB with 3 dB bandwidth of 14.6 GHz. Two of these MMICs are cascaded and packaged using WR-10 waveguide interface with broadband microstrip to waveguide E-plane probe transitions at input and output. The packaged LNA has a nominal gain of 20.5 dB with 3 dB bandwidth of 13 GHz. Measured noise figure (NF) is less than 6.5 dB over the bandwidth with a minimum of 5.3 dB at 87 GHz.