A Broadband Ultracompact Power Amplifier Applying Distributed Balun With Harmonic Control

This letter presents a self-packaged, broadband ultracompact differential power amplifier (PA) using hybrid integrated suspended line (HISL) technology. The key innovations include: 1) a hybrid matching network combines distributed elements [baluns, transmission lines (TLs)] and lumped components (dual-layer spiral inductors, interdigital/parallel-plate capacitors) to simultaneously achieve ultra broadband matching (1.4–5.3 GHz) and power combining, overcoming the bandwidth-efficiency-size tradeoff in PA design and 2) a miniaturized harmonic control network leveraging dual-layer spiral inductors and capacitors, replaces bulky distributed counterparts and enables the PA to achieve second harmonic (2har) tuning while maintaining a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.291~\lambda _{g}^{2}$</tex-math> </inline-formula> footprint and 108.2 W/<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{g}^{2}$</tex-math> </inline-formula> power density. A detailed theoretical derivation of the proposed network is provided. Benefiting from the inherent self-packaged architecture, the PA eliminates external parasitics and enhances thermal stability, delivering 44.98 dBm peak saturated output power with 33%–66% efficiency across the band.