A 28-90-GHz GaN Power Amplifier MMIC Using an Integrated fT-Doubler Topology

In this paper, we present a GaN-based f
T
-doubler topology using a novel integrated layout. This compact approach allows for minimizing the layout-induced parasitic effects and, as a result, enables operation at millimeter-wave frequencies. In order to demonstrate the broadband potential of the f
T
-doubler topology employing the novel integrated layout approach, a 3-stage amplifier is reported. It can provide more than 10 dB of small-signal gain over a 28-90-GHz band, which is equivalent to a fractional operating bandwidth of 105 % (1.68 octaves). In large-signal operation, this MMIC can deliver from 14.5 dBm to 20.6 dBm of output power over a 30-90-GHz band. This circuit is able to provide a full coverage of the Q-band (33–50 GHz), U-band (40–60 GHz), V-band (50–75 GHz), E-band (60–90 GHz), and almost the entire Ka-band (26.5-40 GHz). To the best of our knowledge, this is the first demonstration of an FET-based integrated f
T
-doubler circuit operating at such high frequencies.