Power amplifier linearization architecture with complementary filtering for broadband signal transmission

Abstract

This paper proposes a power amplifier (PA) linearization architecture with complementary filtering to realize high-linearity broadband signal transmission. The architecture fully leverages the advantages of analog and digital filtering techniques, ensuring high harmonic suppression within a compact size and reducing the demand for digital resources. A miniaturized triple-mode bandpass filter (BPF) with a wide stopband is integrated, which effectively suppresses the harmonic components of the PA output. Meanwhile, digital filtering is employed to mitigate intermodulation distortion (IMD) that cannot be effectively suppressed by the integrated analog filter, thus forming a complementary filtering digital predistortion (CF-DPD). As the CF-DPD herein focuses only on addressing the residual distortion left by analog filtering, it naturally reduces the system's sampling rate requirements. Experimental results demonstrate that the proposed filtering power amplifier with integrated feedback port (FPA-FB) delivers 38.7-40.5 dBm output power, 8.4-11.9 dB gain, and a peak power-added efficiency (PAE) of 42.6%-52.1%. The prototype occupies an overall size of 67 mm×32 mm, corresponding to 1.1λ_g×0.5λ_g, indicating a compact implementation. Moreover, when transmitting a 400-MHz 5G new radio (NR) signal, the system achieves a normalized mean square error (NMSE) of -32.2 dB and an adjacent channel leakage ratio (ACLR) of -45.1/-47.2 dBc at a reduced sampling rate of 850 mega samples per second (MSPS).

Keywords

Broadband linearization / Digital predistortion / Multimode filter / Power amplifier (PA)

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