A Compact Ka-Band Transformer-Coupled Power Amplifier for 5G in 0.15um GaAs

In this paper we present the design of a compact and broadband transformer-coupled power amplifier in a 0.15μm GaAs technology. The power amplifier achieves an output power of 26.5dBm and 31% power added efficiency, 12.6dB of small signal gain with a fractional bandwidth of 40%. The amplifier enables up to 21.6dBm, 19.9dBm of average output power while amplifying a 6Gb/s, 9Gb/s 64-QAM signal respectively at 28GHz with an EVM<; -25dB without any digital pre-distortion. To the author's knowledge, this is the first time transformer-coupled matching networks are used in a GaAs power amplifier leading to very compact matching structures compared to bulky transmission line.