100 MHz–8 GHz linear distributed GaN MMIC power amplifier with improved power-added efficiency

We report on a multi-octave (100 MHz-8 GHz), linear nonuniform distributed amplifier (NDPA) in a MMIC architecture using scaled 120-nm short-gate-length GaN HEMTs. The linear NDPAs were built with six sections in a nonuniform distributed amplifier approach, where each cell consists of main and g _m3 cells. The small signal gain was >10 dB over the band, with saturated CW output power of ~35 dBm at Vdd = 17 V. The PAE improved by 7%-10% within the band compared to the previous NDPA with 150-nm gate-length GaN FETs. Based on two-tone testing, the linear NDPA showed improved OIP3 of ~50 dBm, compared to OIP3 of 42 dBm for the NDPA without linearization. Under QPSK LTEwaveform, the ACPR1improved by ~10 dBc at average output power of 23 dBm, without digital pre-distortion.