A GaAs-based 3-40 GHz distributed mixer with cascode FET cells

A broadband MMIC distributed mixer with cascode FET cells was developed using commercial GaAs PHEMT foundry. The fabricated distributed mixer with a size of 1.8 mm/spl times/1.0 mm showed a high conversion gain of 3.6 dB/spl plusmn/0.5 dB over 3 to 40 GHz RF frequency ranges at the low LO power level of 5 dBm with a fixed IF frequency of 1 GHz. An average single-sideband noise figure was 11.7 dB without IF post amplification. The LO-to-IF and LO-to-RF isolations were better than 19 dB over the entire operating frequency band. To our knowledge, this corresponds to the highest gain-bandwidth product (85 GHz) achieved from the wideband mixers.