A U-band broadband power amplifier MMIC in 100 nm AlGaN/GaN HEMT technology

The design and manufacture of a three-stage broadband power amplifier is presented in this paper. The amplifier MMIC is realized using AlGaN/GaN HEMTs with a gate-length of 100 nm in a grounded coplanar transmission line technology. A small-signal gain of over 20 dB was measured in the frequency range from 38 to 62 GHz (U-band) for the designed amplifier. This corresponds to a very high small-signal bandwidth of over 48 %. Related to the current-gain cutoff frequency, the bandwidth of the amplifier is 30 % of f(T) and the gain-bandwidth-product is approximately five times f(T). Furthermore, a high continuous-wave saturated output power of 25.8 dBm (380 mW) and a high saturated power density of over 1 W/mm in the output stage are provided by the MMIC.