Mitsubishi Electric Develops 28GHz High-Efficiency GaN Doherty PA for mmWave 5G
The Ka band is a popular frequency for mmWave applications for 5G communications. High-efficiency and high-output PAs are required to reduce power consumption and increase data transmission distance. Mitsubishi Electric engineers were challenged to meet the requirements for a PA with high output power and high efficiency at backoff output power by designing a 28GHz PA MMIC using a high-efficiency Doherty architecture
The designers chose Cadence AWR Design Environment platform for this exacting design and believe that the resulting Doherty PA device is the state of the art in 5G amplifier devices for the Ka band.
The parameters of the Doherty output combiner, which consisted of microstrip lines and metal-insulator-metal (MIM) capacitors on a 50µm thickness SiC substrate, were calculated using Microwave Office circuit design software. EM simulations were performed on the Doherty output combiner using the AXIEM planar EM simulator. The fabricated 2-stage Doherty PA using a GaN HEMT achieved a measured saturation output power of 35.6dBm (3.6 W) and peak PAE of 26%. PAE of 23% and 20% was obtained at 6dB and 8dB backoff, respectively.
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