Linearity-optimized class-E GaN HEMT Doherty amplifier

In this paper, we have proposed a linearity-optimized class-E GaN HEMT DPA. To improve linearity without extra linearization techniques, not only the gate biases but also matching circuits of the carrier and peaking cells were optimized. For verification, a class-E DPA was designed and implemented using GaN HEMTs with 25-W PEP and tested using a two-tone signal with 1-MHz tone spacing and a 1-carrier WCDMA signal. The measured two-tone results showed that the class-E DPA optimized at an average output power of 38 dBm delivered the IMD3 of -58 dBc with a PAE of 45.4%. For a 1-carrier WCDMA signal, the class-E DPA produced an ACLR of -32.9 dBc with a PAE of 46.7%. The measured results prove that the proposed class-E GaN HEMT DPA can be a promising solution for high- performance PA.