Uniplanar monolithic frequency doublers

GaAs monolithic frequency doublers in the 13-GHz band and 26-GHz band were designed and fabricated. These doublers use a uniplanar monolithic microwave IC (MMIC) structure. They are composed of coplanar waveguides, slotlines, and air bridges only on the upper side of the GaAs substrate. These uniplanar MMIC frequency doublers offer the advantages of smaller circuit size and simpler fabrication processes than microstrip-based MMICs. The fabricated doublers achieve a conversion gain of 2.9 dB at 12.4 GHz and a minimum conversion loss of 0.7 dB at 24.4 GHz. A 6.5-26.0-GHz frequency quadrupler is presented that uses a cascade connection of the doubler chips. It demonstrated stable operation without any adjustment and achieved a conversion loss of 10 dB.>