C–Ku-Band RF-Input Load Modulated Balanced Amplifier MMIC Utilizing Broadband Saturation Efficiency Enhancement Technique
Kang Li, Aimin Wu, Wenhua Chen, Xiaofan Chen
Abstract
This article presents a C-Ku-Band 10 W RF-input load-modulated balanced amplifier (LMBA) monolithic microwave integrated circuit (MMIC) with enhanced power added efficiency (PAE) at saturation. In contrast to previous studies of LMBA that focus on efficiency enhancement in the back-off region, this article investigates the potential of LMBA architectures to improve the saturation efficiency of ultra-wideband (UWB) power amplifiers (PAs), which are widely used in radar and electronic warfare systems. The load modulation mechanism of LMBA is utilized to improve the impedance matching condition of power transistors across multioctave bandwidth, thereby reducing the mismatch loss (ML) and enhancing the output power and efficiency. Moreover, the load modulation circuit is further integrated with the main BPA to alleviate the requirement of additional control signals. For demonstration, a 6–18 GHz RF-input LMBA MMIC is implemented based on 150-nm GaN HEMT technology. Under CW measurement conditions, the MMIC achieves a small signal gain of 18.5–23.6 dB, a saturated output power of 40.3–42.2 dBm, and a PAE of 25%–40% across the entire band. To the best of the author’s knowledge, this work is the first that demonstrated RF-input LMBA MMIC across the C-Ku-band and achieves the highest saturated PAE among the previously presented 6–18 GHz PA MMICs.