6–18GHz Watt-Level Switchless Dual-Band PA MMIC Using Coupled-Line-Based Diplexer

In this work, a watt-level switchless dual-band power amplifier (PA) has been developed for multi-octave operation. To switchless dual-band operation, we proposed a new coupled-line based diplexer structure at the inter-stage and output-stage of the PA. Detailed analysis is performed to show the operation principle of the proposed diplexer. The designed dual-band PA is fabricated with commercial 0.25-µm GaN HEMT process. Fabricated PA shows over 15 dB small-signal gain at 5–11 GHz in low-band mode and 9–18 GHz in high-band mode. The measured average output power and power-added efficiency (PAE) is 35 dBm, 23% at low-band mode and 37 dBm, 26% at high-band mode.