This paper presents the integration of a band-limited memory polynomial (BL-MP) digital pre-distortion (DPD) model with low-resolution Σ∆-based feedback receivers, specifically targeting 6G FR3 carrier aggregation using a 400 MHz OFDM 64QAM signal. The performance is evaluated using two power amplifiers (PAs)—Doherty and Class AB—with distinct nonlinearity profiles. The study compares the Generalized Memory Polynomial (GMP) model with the BL-MP model. Significant improvements in error vector magnitude (EVM), approximately 0.7 dBm at the 3% threshold, are observed for both PAs relative to the GMP-LS model. Additionally, adjacent channel leakage ratio (ACLR) enhancements of around 7 dB are achieved, further surpassing GMP-LS performance. These findings demonstrate the adaptability and effectiveness of the BL-MP model, delivering substantial performance gains over conventional pre-distortion techniques across varied PA architectures.The results highlight the potential of employing a BL-MP DPD with a low-resolution feedback receiver, offering an optimal solution for DPD applications in 6G FR3.

In this paper, a spectral structure analysis for the FFT-based subband digital predistortion is performed. This analysis consists in investigating whether the spectrum of the signal at the output of the power amplifier (PA) shows any particular structuring of the information. Various scenarios are investigated by simulation and validated by experiments, on a real PA. It is found that some spectral zones are more critical than others to maintain good linearization, which makes possible to reduce the requirements of the feedback path.

A novel low-power wideband mixed-signal approach to linearize RF power amplifiers (PAs) is presented. The proposed mixed-signal predistorter (MSPD) is based on FIR memory polynomial (FIR-MP) model, where digital FIR filter improves the memory correction performance without any bandwidth expansion and the MP predistorter in analog baseband provides superior linearization. MSPD avoids 5X bandwidth requirement for the transmitter and the power-hungry RF components when compared to digital predistorters (DPDs) and analog-RF predistorters (ARFPDs), respectively. This makes the MSPD solution a very low-power candidate and especially attractive in the context of small-cell base stations. Extracted PA model of a commercial 1 W GaAs HBT PA is linearized over an 80 MHz signal; results prove that the FIR-MP based MSPD in ideal system-level simulations provides an improvement of 14.3 dB and 13.5 dB, in adjacent and alternate channel leakage ratio, ACLR1 and ACLR2, respectively, in comparison with FIR envelope memory polynomial (FIR-EMP) model, used in ARFPD. The impact of various non-idealities are simulated at electrical-level to derive the requirements for the integrated circuit implementation shows that a resolution of 8 bits for the coefficients and a signal path SNR of 60 dB is required to achieve ACLR1 above 45 dBc, with as little as 9 coefficients in the analog domain.