A K-band AlGaN/GaN-based MMIC amplifier with microstrip lines on sapphire

We present a K-band AlGaN/GaN HFET MMIC amplifier with integrated microstrip lines on sapphire. The microstrip lines with via-holes through chemically stable sapphire are successfully formed for the first time by using a novel laser drilling technique. AlGaN/GaN HFETs with superlattice capping layers in the MMIC exhibit RF performance with ƒ
max
of 160GHz and NF
min
of 2.5dB at 28GHz. The fabricated 3-stage MMIC amplifier exhibits a small-signal gain as high as 22dB at 26GHz with a 3dB bandwidth of 4GHz. The presented K-band MMIC would be applicable to future millimeter-wave communication systems.