Mitsubishi Electric Develops 28-GHz GaN Doherty PA for mmWave 5G
Mitsubishi Electric is one of the world’s leading names in the manufacture and sales of electrical and electronic products and systems used in a broad range of fields and applications.
The Ka band is a popular frequency for mmWave applications for 5G. High efficiency and high output power amplifiers (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 28-GHz PA MMIC using a high-efficiency Doherty architecture.
The designers chose NI 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 50-µm thickness SiC substrate, were calculated using Microwave Office circuit design software. Electromagnetic (EM) simulations were performed on the Doherty output combiner using the AXIEM planar EM simulator. The fabricated 2-stage Doherty PA using a GaN high electron mobility transistor (HEMT) achieved a measured saturation output power of 35.6 dBm (3.6 W) and peak PAE of 26%. PAE of 23% and 20% was obtained at 6 dB and 8 dB backoff, respectively.
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