Load Modulated Balanced Amplifier Design Method Based on Complex Impedance Trajectories

Kimon Vivien (1) , Paolo Enrico de Falco (2) , Olivier Venard (1) , Geneviève Baudoin (1) , Pascal Pierre-Charles-Felix (3) , Taylor Barton (2)

1 ESYCOM - Electronique, Systèmes de communication et Microsystèmes
2 University of Colorado [Boulder]
3 Auteur indépendant

This paper presents a design methodology for a load modulated balanced amplifier (LMBA) focusing on AMPM distortion mitigation. By introducing second harmonic control as a degree of design freedom, a complex load trajectory can be selected to compensate for AMPM nonlinearities in the device without substantially affecting efficiency. A mathematical derivation is accompanied by a design procedure based on closed-form equations to fabricate an LMBA based solely on load-pull data. The theory is validated through the measured comparison of three different designs operating at 2.4 GHz in a pseudo-RF-input Doherty-like LMBA configuration, with class-J, -B, and -J* main PAs. The class-J prototype outperforms the other designs with 54% and 49% drain efficiency at peak output power and 6-dB back-off, respectively, and only 4 degrees of AM-PM across this power range. When driven with a 10-MHz, 8.6-dB PAPR LTE signal, 40.5% average efficiency is achieved with better than −40.5 dBc ACLR without digital predistortion.

Mots clés: Class J; Doherty power amplifier; gallium nitride; load modulated balanced amplifier; power amplifiers

Domaines: Electronique

Kimon Vivien, Paolo Enrico de Falco, Olivier Venard, Geneviève Baudoin, Pascal Pierre-Charles-Felix, et al.. Load Modulated Balanced Amplifier Design Method Based on Complex Impedance Trajectories. IEEE Journal of Microwaves, 2022, 2 (1), pp.199-213. ⟨10.1109/JMW.2021.3129168⟩. ⟨hal-03526044⟩