A linear 4W power amplifier at K-band using 250nm AlGaN/GaN HEMTs

This paper presents the design, realization, and measured performance of a K-band high power amplifier using an AlGaN/GaN HEMT on semi-insulating SiC technology with a gate length of 250 nm. The amplifier is a two-stage design with a staging ratio of 1:2. It employs a 6×90 μm driver cell and two 6×90 μm cells in the second stage. Using a drain supply voltage of 28V, the amplifier delivers a saturated output power of >4W (36 dBm) and exhibits a peak PAE of 34 %, both at a frequency of 22 GHz. When biased for peak PAE, the linear gain is 16 dB. Intermodulation measurements at 22GHz with 1MHz two-tone spacing show a third-order (OIP₃) and fifth-order output intercept point (OIP₅) of 40dBm and 35 dBm, respectively. A third-order intermodulation ratio C/IM3 of >16 dB is achieved at an output power of 1W per carrier.