Digital Predistorters Go Multidimensional: DPD for Concurrent Multiband Envelope Tracking and Outphasing Power Amplifiers

Machine-Learning Assisted Optimisation of Free-Parameters of a Dual-Input Power Amplifier for Wideband Applications

“…The BPA signal is directly defined as . While the CSP signal is generated by using a shaping function previously employed in envelope tracking (dynamic supply modulation) and outphasing (dynamic load modulation) applications [ 26 ], because it provides two degrees of freedom. As will be described in the following, with one of the parameters it is possible to prevent the signal from dropping to zero, while with the other it is possible to control the shape of input–output characteristic.…”

On-Demand Real-Time Optimizable Dynamic Model Sizing for Digital Predistortion of Broadband RF Power Amplifiers

“…(e-mail: yue.li1@ucdconnect.ie; anding.zhu@ucd.ie) piecewise Volterra [13], decomposed vector rotation (DVR) [14] and magnitude-selective affine (MSA) [15]. Though these models achieve good performance and have substantially lower complexity than the full Volterra series, they may still require significant resources to comply with the linearity requirement posed by future wideband and multiband transmitters [16]. Moreover, as they define their basis functions based on prior knowledge on general PA behaviors [17], it is difficult to acutely adapt these models to individual PA characteristics and varying operation conditions.…”

Beyond the Moore-Penrose Inverse: Strategies for the Estimation of Digital Predistortion Linearization Parameters

“…The DPD coefficients can be estimated/adapted iteratively in a processing system (PS) unit on a much slower time scale than in the forward path (i.e., not in real-time), unless the PA timevariant behavior changes so fast that it requires real-time adaptation. There is plenty of literature addressing the problem of PA and DPD behavioral modeling to characterize nonlinear and dynamic behavior when considering wide bandwidth signals [1]- [2], carrier aggregation, multiband or multiantenna configurations [3]- [4], or taking into account high-efficiency amplification topologies (e.g., Doherty PAs, load-modulated balanced amplifiers, envelope tracking PAs, or outphasing transmitters) [5]- [6]. The DPD function in the forward path is often implemented as a weighted sum of nonlinear basis waveforms.…”