Design of a wideband symmetric large back-off range Doherty power amplifier based on impedance and phase hybrid optimization

The present paper proposes an optimization design method for the Doherty output matching network (OMN) using impedance–phase hybrid objective function constraints, which possesses the capability of enhancing the efficiency consistency of the Doherty power amplifier (DPA) using integrated enhancing reactance (IER) during the back-off power (BOP) range. By calculating the desired reactance for an extended BOP range and combining it with the two-impedance matching method, the S-parameters of the OMN are obtained. Meanwhile, the impedance and phase constraints of the OMN are proposed to narrow the distribution range of the IER. Furthermore, a fragmenttype structure is employed in the OMN optimization so as to enhance the flexibility of the circuit optimization design. To validate the proposed method, a 1.7–2.5 GHz symmetric DPA with a large BOP range was designed and fabricated. Measurement results demonstrate that across the entire operating frequency band, the saturated output power is >44 dBm, and the efficiency ranges from 45% to 55% at a 9-dB BOP.