Efficiency-Enhancement of GaN PAs for 5G transmitters
GaN transistors and MMICs have been demonstrated into the 20-GHz range with commercial foundry processes, with efficiencies above 60% at X-band for 2-stage PAs with output power levels on the order of 10W. This talk discusses scaling of GaN PAs to the millimeter-wave 5G bands for amplifying challenging broadband, high peak-to-average power ratio (PAPR) signals. Efficiency enhancement techniques such as supply modulation and various load modulation techniques (outphasing, Doherty, etc.) are overviewed and compared in terms of efficiency, linearization requirements and overall transmitter complexity. Experimental efficient X-band MMICs are presented, along with K and Ka band scaling in existing technologies.