A 2–18 GHz Dual-Mode GaN Power Amplifier Based on Distributed Structure

Based on 0.2- <tex-math notation="LaTeX">μ</tex-math> m GaN HEMT high-voltage process, a ultrawideband (UWB) dual-mode power amplifier (PA) was designed using the distributed structure. Different from distributed amplifiers in conventional low-pass filtering networks, <tex-math notation="LaTeX">$LC$</tex-math> series resonant networks are used to regulate the filtering characteristics. The switching transistors are used in the design to convert the low-pass and bandpass characteristics of the gate artificial transmission line, so as to realize the conversion of 2–18 GHz continuous wave (CW) and 8–12-GHz pulse two working modes. When the drain voltage ( <tex-math notation="LaTeX">VD</tex-math> ) is 28 V, the amplifier can achieve 10-W CW power output at 2–18 GHz with power added efficiency (PAE) greater than 20%. When <tex-math notation="LaTeX">VD</tex-math> is 40 V, the pulse output of 20 W at 8–12 GHz can be achieved, and the peak PAE can reach 35%. The innovative method of switching transistor combined with <tex-math notation="LaTeX">$LC$</tex-math> resonant network rematches the PA to obtain high PAE in the desired BW under high-voltage operation.