Input‐harmonic manipulated wideband high‐efficiency series of continuous mode power amplifier

• Published in: International journal of circuit theory and applications 2024-12, Vol.52 (12), p.6083-6096
• Main Authors: Xuan, Xuefei, Cheng, Zhiqun, Zhang, Zhiwei, Le, Chao, Gong, Tinwei
• Format: Article
• Language: English
• Subjects: a series of continuous modes (SCMs); Broadband; Frequency ranges; Gallium nitrides; Harmonics; high‐efficiency; Impact analysis; Nonlinearity; power amplifier (PA); Power amplifiers; second source harmonics; wideband
• ISSN: 0098-9886; 1097-007X
• DOI: 10.1002/cta.4058

Summary In this paper, a systematic research of the effects of second source harmonics caused by gate‐source capacitance in the design of a series of continuous mode (SCM) power amplifiers (PAs) is first presented. The research results show that, compared to the conventional SCMs that require the input second harmonic to be short circuited, SCMs under the impact of input nonlinearity have a more flexible input second harmonic manipulation space, and to further improve and maintain the performance of PAs in wideband operations, a new impedance design space is explored through analysis. For practical validation, SCMs PA considering the effects of the input nonlinearity is designed and fabricated with a 10‐W gallium nitride (GaN) device, acquiring 39.1–42 dBm output power and 60.6–71.5% drain efficiency (DE) performance at a 3 dB gain compression level operating over the 0.5–3.5 GHz frequency range with a relative bandwidth of 150%. The figure shows the trend of the theoretically achievable efficiency with the variation of nonlinear factor γ and adjustment factor ξ. It is evident that as γ varies from −0.5 to 0.5, the drain efficiency has significantly improved under different operating modes, including continuous Class‐B/J mode, maximum flat Class‐F mode, and continuous Class‐F mode. This is consistent with the conclusion of the waveform analysis. The family of drain current waveforms undergoes distortion under the influence of input nonlinearity, resulting in the overlapping area of the voltage waveform varying with γ, thereby affecting DE. Based on this, the conclusion that maintaining γ ≥ 0 can improve efficiency can be obtained.