Doherty Amplifier Linearization in Experiments by Digital Injection Methods

Abstract

In this paper, the experimental verification of two linearization methods applied on a broadband two-way microstrip Doherty amplifier is performed. The laboratory setups are formed to generate the baseband nonlinear linearization signals of the second-order. After being tuned in magnitude and phase in the digital domain the linearization signals modulate the second harmonics of fundamental carrier. In the first method, adequately processed signals are then inserted at the input and output of the main Doherty amplifier transistor, whereas in the second method, they are injected at the outputs of the Doherty main and auxiliary amplifier transistors. The experimental results are obtained for 16QAM and 64QAM digitally modulated signals.

Doherty Amplifier Linearity Test for Fifth Generation Signals

“…The DEB_LIN technique was experimentally approved on the ADA for the 16QAM signal with 1 MHz useful signal frequency bandwidth and also for the 64QAM signal with 2 MHz useful signal frequency bandwidth [5], [7], [8]. This linearization technique uses adequately processed baseband signals that modulate the carrier second harmonic, and a detailed explanation of the technique operation can be found in the mentioned literature [3]- [8].…”