An interference on a concurrent 4.5-/8.5-GHz-band operation has been effectively suppressed by applying a duplexer technique to high-efficiency GaN HEMT power amplifiers. Each harmonic was also suppressed by a harmonic reactive termination used for a high-efficiency operation. The developed concurrent dual-band amplifier delivered a 73% drain efficiency and a 61% power-added-efficiency (PAE) with 32 dBm output power at 8.24 GHz and a 69% drain efficiency and a 64% PAE with 37 dBm output power at 4.70 GHz. Undesired cross-modulation and intermodulation signals at nearby bands occurring due to dual-band interaction have been successfully suppressed to less than -41 dBc.
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