Application of Spoof Surface Plasmon Polaritons for the Design of Sequential Load Modulated Balanced Amplifier

ABSTRACT Spoof surface plasmon polariton (SSPP) controls and manipulates electromagnetic waves in the microwave frequency range through ultrathin corrugated metallic strips, making it suitable for use with microwave devices. In the current state of research, SSPPs are primarily used to design passive circuits and single‐device power amplifiers (PAs). This study combines the SSPP design methodology with sequential load modulated balanced amplifiers (SLMBA) topology to develop a high back‐off (BO) efficiency load‐modulated PA. By using the proposed SSPP theory and method, input and output matching networks based on slow‐wave metamaterials are designed for balanced amplifiers (BAs) and carrier amplifiers (CAs) in the SLMBA. The designed metamaterial‐based SLMBA was fabricated and demonstrated to have a saturated output power of 43 dBm, a BO range of 10 dB, and a BO efficiency maintained above 56.5% within the frequency range of 1.8–2.1 GHz, with a size of 72 mm × 101 mm, which represents a 38% reduction in size when compared to traditional transmission‐line‐based SLMBAs. A 20‐MHz 5G NR signal has been used to implement digital pre‐distortion (DPD) and enhance SLMBA linearity.