Design of Sequential Load Modulation Balance Amplifier Using Multiobjective Particle Swarm Algorithm

In this article, a multiobjective particle swarm optimization (MPSO) method is presented for the design of a sequential load modulation balanced amplifier (SLMBA). Based on the proposed method, the matching networks of the control amplifier (CA) and balanced amplifier (BA) are optimized separately in order to achieve optimal load modulation behavior. Furthermore, the effect of the phase offset line of the SLMBA is analyzed and optimized. In order to validate the proposed method, a SLMBA with a frequency range of 1.8–2.1 GHz was implemented and measured. Consequently, it is capable of achieving a saturation drain efficiency (DE) of 70.1%–74.3%, a saturated output power of 43.7 dBm, and a DE of 52.3%–57.9% with 10.5-dB output back-off. In order to improve the linearity of the manufactured SLMBA, a digital predistortion method has been implemented, and a 20-MHz 5GNR signal has been used to test the device with good results.