A Hybrid Heuristic Search Control Assisted Optimization of Dual-Input Doherty Power Amplifier

This paper proposes an auto-tuning approach to find the optimal configuration of a dual-input Doherty power amplifier (DIDPA) to enhance power efficiency while maintaining a good linearity level. The DIDPA configuration consists of a set of circuits and system-level parameters called free-parameters that are optimized through a hybrid heuristic search control (HHSC), which is the core of the auto-tuning approach. The HHSC convergence towards the optimal solution is conducted by a cost function designed to present a trade-off between efficiency and linearity. The HHSC was validated through experimental using a 20 MHz LTE signal at 3 GHz, where DIDPA exhibited a drain efficiency (DE) of 60% at an output power level of 36 dBm. The linearizability of DIDPA has been validated through digital predistortion (DPD), where the error vector magnitude (EVM) is reduced to 2.5%, and the adjacent channel power ratio (ACPR) is improved to −48 dBc.