A GaAs HBT Doherty Power Amplifier with 31 dBm Linear Output Power and 43% Efficiency by Using Dynamic IM3 Cancellation

This paper presents a comprehensive design of three stage fully differential linear Doherty power amplifier (DPA) for 5G new radio (NR) handset applications with low supply voltage 3.4V. It is implemented by 2-um GaAs HBT Flip-chip process for PA and 6-layer laminate substrate process for output transformer and matching networks. The size and load impedance of amplifier in the peak path were optimized to cancel the non-linearity components of carrier amplifier dynamically. For continuous-wave (CW) signal, the implemented DPA module exhibited a saturation power of 34 to 35.3 dBm, and PAE of 42 to 52% at full N77 band. Using the 5G new radio 100-MHz QPSK signal, this work shows high linear power of 31 dBm with 43% PAE and 30 dBm with 33% PAE at N78 and N77 band, respectively. The corresponding adjacent channel leakage ratios (ACLRs) are lower than -40dBc without digital pre-distortion (DPD).