An 18-38-GHz K-/Ka-Band Reconfigurable Chireix Outphasing GaAs MMIC Power Amplifier

This article presents a frequency-reconfigurable outphasing GaAs power amplifier MMIC operating over an 18–38-GHz range with 2–6-GHz RF bandwidth per frequency setting. The architecture is based on a broadband power combining structure providing nonisolating power combining. Reconfigurable shunt elements based on p-i-n diode switches control the Chireix reactance compensation to enable frequency-reconfigurable efficiency enhancement at output power back-off (OBO). The prototype two-stage MMIC is characterized under CW and modulated measurements demonstrating 20–24-dBm saturated output power over the band 18–38 GHz, with measured PAE of 23%–31% at peak and 17%–23% at 6-dB OBO. When measured with a 200-MHz LTE signal with 9-dB PAPR centered at 19.5 GHz, the PA performs with 15.3% average efficiency at a 14.3-dBm average output power with 24.18-dBc ACLR.