Abstract
The Saleh behavioral model exhibits high prediction accuracy for nonlinearity of traveling-wave tube power amplifiers (TWT-PAs). However, the accuracy of the Saleh model degrades when modeling solid-state power amplifiers (SSPAs) technology. In addition, the polynomial expansion of the Saleh model consists of only odd-order terms as analyzed in this work. This paper proposes a novel model accuracy enhancement for the Saleh amplitude-to-amplitude (AM/AM) model when applied to radio frequency (RF) SSPAs. The proposed model enhancement accounts for the second-order intermodulation distortion, which is an important nonlinearity challenge in wideband wireless communications. The proposed static AM/AM model is a three-parameter rational function, which exhibits low complexity compared to the state-of-the-art behavioral models. A transpose architecture of finite-impulse digital filter is used to quantify the memory effect in SSPAs. A least-squares method is used for extracting all the model parameters. A linearization technique using a three-parameter digital predistortion model is also calculated to compensate for the AM/AM nonlinear distortion in SSPAs. Finally, the identification and evaluation of the enhanced Saleh model is presented based on measurements of RF SSPAs.
Highlights
The rapid evolution of wireless communications requires high dynamic range radio frequency (RF) power amplifiers (PAs) to efficiently operate on high-amplitude fluctuations in modern digital modulation [1]
The AM/AM conversion of a gallium arsenide (GaAs) RF PA is measured by sweeping the input amplitude of a
These results show a model improvement of around 4dB normalized mean square-errors (NMSE) compared to the original Saleh model
Summary
The rapid evolution of wireless communications requires high dynamic range RF power amplifiers (PAs) to efficiently operate on high-amplitude fluctuations in modern digital modulation [1]. An accurate estimation of the model smoothness in the amplitude-to-amplitude (AM/AM) transition from the linear to the saturation regions has been a topic of interest in the state-of-the-art PA modeling [8,9,10,11,12]. This is because operating SSPAs near the compression region is often required for achieving high power efficiency and transmitting signals of high peak-to-average power ratio (PAPR) [13].
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