Broadband GaN DHFET Traveling Wave Amplifiers with up to 120 GHz Bandwidth

We report MMIC traveling-wave amplifiers (TWAs) fabricated using a 40 nm GaN double heterostructure FET (DHFET) technology. By varying the gate periphery within cascode gain stages, we produced a family of TWA designs with a range of gain and bandwidth and approximately 300 GHz gain- bandwidth product. The TWA with the widest bandwidth had >120 GHz of 3-dB bandwidth, with 7.3 dB gain, 6 dB noise figure (NF), and saturated output power of 19 dBm at 20 GHz. Our TWA that was optimized for performance at lower frequencies had 1-50 GHz bandwidth with 16 dB gain, 1.7 dB minimum NF, and 27 dBm output power at 20 GHz. These circuits represent record MMIC performance for GaN in terms of bandwidth and gain-bandwidth product, and are very promising for broadband amplifier applications where low noise figure, and ultra- high linearity, dynamic range and survivability are required.