A 28 GHz Doherty PA with 22.9% PAEmax and 17.4% PAE at 6-dB PBO in 0.13μm SiGe Technology for 5G Application

This paper presents an mm-wave Doherty PA in a Infineon 130-nm SiGe BiCMOS for output power and back-off efficiency optimization for 5G communications. The output stage of the main PA and the auxiliary PA use a stacked topology for high output power without trading the power gain. A voltage-combiner with a transformer-based output matching network is proposed to achieve a true Doherty load modulation in a wide signal bandwidth while maintaining a compact layout. The PA is fabricated with Infineon 0.13 $\mu\mathrm{m}$ SiGe BiCMOS technology with a core area of 0.36 $\text{mm}^{2}$. At 5G 28 GHz, the measured OP1db is 22.9 dBm, and PAE at 6-dB PBO is 17.4%. At 28 GHz with 400 MHz bandwidth, it shows an EVM of 5% with average output power $(\mathbf{P}_{\text{avg}})$ of 15.32 dBm with 14.6% PAE.