Watt level GaAs PHEMT power amplifiers 26 GHz and 40 GHz for wireless applications

The authors report on the design, fabrication and performance of 1 W amplifiers for 26 GHz and 40 GHz. The design approach uses standard MMIC elements: microstrip transmission lines, MIM capacitors, through-the-substrate vias for low impedance ground connection, two metal levels, air bridge crossovers and 75 /spl mu/m substrates. The substrate material is grown by MBE, and for higher output power has double heterojunction channels. A Leica 10.6 electron beam lithography (EBL) machine defined the transistor gates. The gates are nominally 0.18 /spl mu/m long. A plasma process that achieves excellent yield and reproducibility provides the gate recess.