Novel Design Space of Load Modulated Continuous Class-B/J Power Amplifier

Abstract

A novel design space of load modulated (LM) continuous Class-B/J power amplifiers (PAs) is proposed, and a detailed mathematical analysis is presented. The combination of LM technique and continuous mode is introduced to enhance the wideband performance of LM PAs. An inversely proportional relationship between $Z_{L}$ and $C_{\mathrm {out}}$ is derived, which indicates that the nonlinear $C_{\mathrm {out}}$ can affect the optimal load impedances at output power backoff (OPBO) and the design parameter $\beta $ should be appropriately adjusted. The measured results of a PA prototype show that the PAE is 39%–45% under LM when OPBO = 5 dB across 1.6–2.4 GHz. Compared with the same PA with fixed $V_{\mathrm {var}}$ , the proposed PA with optimum $V_{\mathrm {var}}$ at 2 GHz achieves a PAE improvement with 11% when OPBO = 5 dB.