Fabrication and characteristics of cascade connected AlGaN/GaN HEMTs grown on sapphire substrates are reported.The circuit employs a common source device,which has a gate length of 0.8μm cascode connected to a 1μm common gate device.The second gate bias will not only remarkably affect saturated current and transconductance,but also realize power gain control.Cascode device exhibits a slight lower of f T,a less feedback,a largely greater of maximum available gain and a higher impedance compare to that of common source device.
