A Tunable Analog Predistorter for 5G Power Amplifier Linearization

With the development of the fifth-generation mobile communication system, the characteristics of 5G signals such as large bandwidth, low latency, and complex modulation have become more prominent.To address the limitations of traditional analog predistortion circuits, including insufficient tuning flexibility, challenges in adaptively adjusting power amplifier linearization performance, and poor linearization efficacy under wide bandwidth conditions, this paper proposes a design based on a four-path composite structure.By employing Schottky diodes and field-effect transistors as nonlinear components, the circuit integrates tunable bias voltages and introduces higher-order nonlinear terms. Additionally, microstrip delay lines are incorporated into two of the branches to enhance compensation for the PA′s memory effects.The experiment utilized the analog predistorter to conduct linearization tests on a power amplifier centered at 4.9 GHz.Test results indicated that, for 5G NR signals with bandwidths of 100 MHz and 200 MHz, the predistorter improved the adjacent channel power ratio of the power amplifier by approximately 7 dB~10 dB.