A 2.4–6 GHz Broadband GaN Power Amplifier for 802.11ax Application

This paper presents a 2.4-6 GHz highly integrated broadband GaN power amplifier (PA) with three stages for 2.4-/5-GHz dual-band 802.11ax application. A compact external output matching network is introduced to realize broadband output matching, while reducing the loss of the output matching network and saving the chip area. A novel topology of coupled resonators is exploited for the broadband inter-stage matching to cover the 802.11ax bands from 2.4 to 6 GHz. In the proposed topology, the coupling between the primary and secondary resonators is through a series inductor and a series capacitor. Compared with other conventional coupled resonators, the proposed topology produces an additional complex pole, further extending the bandwidth. The PA was designed and fabricated in Wolfspeed 0.25- μm GaN-on-SiC technology. The implemented PA achieves a saturated output power (P
_sat
) of 35.2-36.3 dBm with a maximum power added efficiency (PAE) of 38-53% from 2.4 to 6 GHz. When tested with an 80-MHz, 256-quadratic-amplitude modulation (QAM) 802.11ax signal, the PA delivers an average output power of 27.1 and 25.7-27.2 dBm with a PAE of 20.9% and 18.4-24.6% in the 2.4-GHz and 5-GHz wireless local area network (WLAN) bands, respectively, while meeting the specification of error vector magnitude (EVM) below -32 dB.