Doherty Load Modulation Based on Non-Reciprocity

This paper presents a new type of Doherty power amplifiers (DPA) based on non-reciprocal power combiners. We replace the conventional quarter-wave
$(\lambda/4)$
impedance inverter in a DPA by a non-reciprocal gyrator. As proof of concept, a DPA using a commercial circulator has been implemented. The prototype PA exhibits a peak output power of 49.1 ±0.1 dBm and efficiency between 57–68 % at 6 dB output back-off (OBO) across 2.08 −2.14 GHz. Linearized modulated measurements, using 10 MHz LTE signal with 7.8dB PAPR, show an average output power of 13 w, an average drain efficiency of 54 %, and an adjacent channel leakage ratio (ACLR) lower than −55 dBc.