A 24 GHz Harmonic-Injection Doherty Power Amplifier with 42% PAE at 6 dB OPBO in 100 nm GaN Technology

This paper presents the design of a two-stage harmonic-injection Doherty power amplifier (HI-DPA) in which a signal at the second harmonic frequency $\left(2 f_{0}\right)$ is injected into the drain of the auxiliary transistor’s power stage. The injected $2f_{0}$ signal is generated by an on-chip single-stage injection power amplifier. The HI-DPA was manufactured on a 100 nm GaN HEMT technology. Preliminary continuous-wave (CW) on-wafer measurements performed at 24 GHz show that the HI-DPA achieves a power-added efficiency (PAE) of 42 % at peak-output-power (POP) and 6 dB output-power-back-off (OPBO) with an associated saturated output power $(P_{SAT})$ of 33 dBm.