2.8-3.8 GHz Broadband InGaP/GaAs HBT Doherty Power Amplifier IC for 5G New Radio Handset

This paper presents a 2.8-3.8 GHz broadband two-stage differential Doherty power amplifier using a 2-µm InGaP/GaAs HBT process for 5G new radio handset applications. A compact transformer-less interstage network is proposed for direct power division for carrier and peaking amplifiers. The power division ratio at the interstage was designed to be dynamically varying according to the input power level to have higher power gain and load impedance modulation for an operating frequency band of as broad as 1 GHz. In addition, active bias circuits for the peaking amplifier were optimized to have sufficient gain expansion so that the overall AM-AM characteristics is as flat as possible. Using the 5G new radio uplink signal with a signal bandwidth of 100 MHz, the implemented Doherty PA IC exhibited a power gain of 31.9 to 38.4 dB, PAE of 22.0 to 30.6%, and average output power of 26.0 to 27.8 dBm at a given ACLR of −33.0 dBc.