A 20-W 1.4–5-GHz Self-Packaged Power Amplifier Using Hybrid Integrated Suspended Line Technology and a Compensated Distributed Balun Network

Abstract

This article presents a 20-W 1.4–5-GHz self-packaged differential power amplifier (PA) using hybrid integrated suspended line (HISL) technology and a compensated distributed balun network that provides the PA optimum load impedance over a wide bandwidth. First, a compensated distributed balun network consisting of two coupled-line sections with compact inductors and capacitors for broadband board-level PAs is proposed. The network extends the bandwidth of board-level two-way PAs by 36.6%~71.6% compared to the same type of PAs and overcomes the challenges of integrating baluns with large packaged power devices with significant parasitics across wide bandwidths by trapezoidal capacitors. Second, closed-form design solutions and design parameters on this new network are derived and analyzed comprehensively to guide the design. Third, the proposed network is designed based on HISL, which is for low loss, small size, and self-packaging. As a proof of concept, a broadband high-gain ultrasmall differential PA with three stages is designed and implemented based on HISL technology, which demonstrates excellent performance and self-packaging. The implemented PA achieves the saturated output power ( ${P} _{\text {sat}}$ ) of 40.5–44.6 dBm with maximum power added efficiency (PAE) of 24.4%–58.3% and 20–28.9-dB power gain from 1.4 to 5 GHz. With a fractional bandwidth over 110%, the PA exhibits a competitive figure of merit (FoM) of 96.7. In addition, an ultrasmall size of $0.68~\lambda _{\text {g}} \times 0.44~\lambda _{\text {g}} \times 0.05~\lambda _{\text {g}}$ is achieved, where $\lambda _{\text {g}}$ is the guide wavelength at 2 GHz.