A High-Linearity Quasi-Darlington Amplifier with Sub-Degree AM-PM for WLAN Applications

This paper presents a power amplifier (PA) with a proposed High-Linearity Quasi-Darlington (HLQD) structure implemented in the GaAs HBT process. The HLQD enables AM-PM compensation between transistors operating at different bias states while maintaining minimal AM-AM distortion. The power stage of PA prototype based on HLQD, operating in the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{5. 6 - 6. 7 ~ G H z}$</tex> frequency band, achieves less than <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{1}^{\circ}$</tex> AM-PM distortion with AM-AM variation less than 0.5 dB for the continuous wave test, with an output power around 1 W and 38% peak power-added efficiency. It demonstrates an average output power of 17.8 dBm while meeting -40 dB EVM requirements under the MCS11 160 MHz 1024 QAM modulated signal, showing promising potential for Wi-Fi 6 and 6E applications.