Integrated coplanar mm-wave amplifier with gain control using a dual-gate InP HEMT

Variable gain mm-wave amplifiers, based on InP high-electron mobility transistor (HEMT) devices, are demonstrated. The two-stage circuits consist of a single-gate (SG) and dual-gate (DG) transistor. The influence of the gate recess depth on the gain control range is investigated. A maximum gain control range of 32 dB is achieved which is the largest reported in the mm-wave range for a monolithically integrated variable gain amplifier (VGA). The maximum gain is 25.7 dB at 48.5 GHz with a 3-dB bandwidth of 10.5 GHz. The circuits were fabricated in coplanar technology.